Version July 2025
INTRODUCTION —
The basic requirements of an optimal insulin regimen include administration of a basal insulin plus mealtime boluses of a rapid-acting, faster rapid-acting, or short-acting insulin. Basal insulin can be delivered by daily or twice-daily injections of an intermediate-acting (neutral protamine Hagedorn [NPH]) or long-acting (glargine, degludec) insulin preparation or by continuous subcutaneous insulin infusion (CSII) via a pump using a rapid-acting or faster rapid-acting insulin preparation (lispro, aspart, glulisine). Providing physiologic insulin replacement requires adjustment of doses to match requirements and relies on glucose monitoring and lifestyle modifications.
This topic will review CSII (insulin pump) therapy. Physiologic insulin replacement, choice of insulin delivery (multiple daily injection [MDI] insulin regimens versus CSII), and designing an MDI regimen are reviewed separately.
●(See "Management of blood glucose in adults with type 1 diabetes mellitus".)
●(See "Overview of the management of type 1 diabetes mellitus in children and adolescents".)
●(See "Type 1 diabetes mellitus in children and adolescents: Insulin therapy".)
GENERAL PRINCIPLES
●Continuous insulin infusion – Continuous subcutaneous insulin infusion (CSII; insulin pump therapy) provides subcutaneous infusion of insulin, usually a rapid-acting or faster rapid-acting insulin analog. Basal insulin requirements are supplied in the form of mini-boluses delivered every five minutes. This "continuous" infusion generally constitutes 40 to 50 percent of the total daily insulin dose. In addition to basal insulin delivery, mealtime insulin bolus doses are given to minimize postprandial glucose excursions. (See 'Dosing' below.)
•Rapid-acting insulin analogs – We suggest rapid-acting insulin analogs (most commonly lispro and aspart) rather than regular insulin for CSII. In a meta-analysis of trials comparing rapid-acting insulin analogs with regular insulin for use in CSII, there was a small but significant reduction in glycated hemoglobin (A1C) with use of insulin analogs (mean difference -0.26 percent, 95% CI -0.47 to -0.06 percent) [1]. It was difficult to analyze hypoglycemia as it was defined differently in the various trials, and continuous glucose monitoring (CGM) was not available. The convenience of being able to administer a rapid-acting insulin immediately before the meal (compared with needing to administer preprandial boluses of regular insulin 30 to 45 minutes before meals), as well as the ability to more quickly correct hyperglycemia, also favor rapid-acting formulations.
•Faster rapid-acting insulin analogs – Limited clinical trial data support comparable efficacy of rapid-acting and faster rapid-acting insulin analogs when used for CSII [2-4]. In one 16-week trial, adults with type 1 diabetes on insulin pump therapy who were randomly assigned to faster-acting aspart exhibited a similar change in A1C to those who used insulin aspart but had a smaller increment in one-hour postprandial glucose (-16.4 mg/dL, 95% CI -25.7 to -7) [2]. Similar findings were reported in a 16-week trial that compared lispro and faster-acting lispro use in CSII [4].
In the aspart trial, time in hypoglycemia (≤70 mg/dL [3.9 mmol/L]) did not differ between the aspart and faster-acting aspart groups [2]. In the lispro trial, time in hypoglycemia (<70 mg/dL and <54 mg/dL (3.9 mmol/L) was lower with faster-acting lispro than with lispro, but faster-acting lispro conferred a higher rate of adverse events (60.5 versus 44.7 percent), primarily infusion site reactions, and infusion-related pain [4].
●Insulin pump components – A variety of insulin pumps are available, and the choice among pumps is largely a matter of individual preference, cost, lifestyle, and compatibility with CGM devices. (See 'Types of insulin pumps' below.)
In a traditional pump, insulin is infused from a reservoir/cartridge within the pump through tubing to a cannula or needle that is inserted subcutaneously (figure 1). The infusion set and site of infusion are changed by the person with diabetes (or their caregiver) every two to three days. The tubing, which connects the infusion set to the insulin cartridge/reservoir in the pump, can be connected to and disconnected from the infusion site without removing the cannula. Many traditional insulin pumps can be used with a CGM device as part of a hybrid closed-loop system. (See 'Insulin only, partially automated systems' below.)
For the patch pump, the insulin reservoir, batteries, and cannula are in a wearable disposable device ("pod"), which delivers insulin subcutaneously (figure 2). The pod is changed every two to three days. Insulin delivery from the pod is controlled wirelessly by a handheld "controller," compatible smartphone, or personal diabetes manager (PDM). (See 'Types of insulin pumps' below.)
●Glucose monitoring – For most adults with type 1 diabetes, frequent testing of glucose levels is necessary to achieve A1C targets safely without frequent or severe hypoglycemia. Self-monitoring allows the user to adjust the doses and timing of insulin administration based on both immediate glucose data and the user's behaviors (eg, exercise and food intake). Many people with type 1 diabetes use CGM continuously and only use blood glucose monitoring (BGM) by fingerstick with a glucose meter when needed (eg, CGM is unavailable or an inaccurate CGM reading is suspected). Most insulin pumps can receive and display glucose data from CGM devices and use such data to automatically adjust basal rate delivery to address both low and high glucose levels. (See 'Types of insulin pumps' below and "Management of blood glucose in adults with type 1 diabetes mellitus", section on 'Components of management' and "Glucose monitoring in the ambulatory management of nonpregnant adults with diabetes mellitus".)
DOSING
Total daily dose — When converting from a multiple daily injection (MDI) insulin regimen to continuous subcutaneous insulin infusion (CSII), the pre-pump level of chronic glycemia will help determine the initial pump basal rate and preprandial dosing. As an example, for a person who has met glycemic goals on the previous MDI regimen (eg, A1C <7 percent), the initial total daily dose (TDD; both short- and long-acting insulin) of insulin administered by the pump may be 10 to 20 percent less than the TDD of the previous regimen. Conversely, individuals who are above glycemic targets and without hypoglycemia may be started with the same TDD as they had been using with their MDI regimens.
Basal rate — In general, approximately 40 to 50 percent of the TDD is administered as the basal rate (divide by 24 to get units per hour). This proportion can be higher or lower depending on a number of factors, including if the individual consumes a low- or high-carbohydrate diet, respectively. For most adults, basal rates are in the range of 0.01 to 0.015 units per kg per hour (ie, for a 60 kg adult, approximately 0.6 to 0.9 units per hour).
For people using automated insulin delivery (AID) systems, basal rate settings dictate insulin delivery only when the insulin pump is used in a nonautomated mode (ie, "manual" mode). (See 'Principles of use' below.)
●Rate adjustments for nonautomated insulin delivery – When using nonautomated insulin delivery, the basal rates are adjusted empirically (eg, by approximately 10 percent) based on glucose monitoring results. (See 'Sensor-augmented insulin pump' below.)
•Clinical variables to consider – The basal rate adjustment depends on several factors, including:
-Individualized glycemic goals
-Frequency and magnitude of hyperglycemia and/or hypoglycemia
-The individual's fears of hypoglycemia and/or hyperglycemia
-Use of continuous glucose monitoring (CGM) with alarms
-Age
-Presence of comorbidities (eg, more cautious adjustments in older adults with hypoglycemia unawareness or cardiovascular disease)
•Time-specific adjustments to basal rate – Certain times of day may require higher or lower infusion rates depending on individual factors including lifestyle patterns and the "dawn phenomenon," which results in an increased need for insulin between 2:00 and 8:00 AM. Most pumps allow for preprogrammed changes in basal rate to accommodate these requirements. The "dawn phenomenon" is thought to result from diurnal secretion patterns of hormones, particularly increased growth hormone at midnight to 2:00 AM, that tend to antagonize the actions of insulin and raise blood glucose concentrations in the early morning hours. The overnight basal rate(s) can be adjusted to maintain the pre-breakfast blood glucose in the target range [5,6], although this strategy is not always effective and may confer risk of hypoglycemia [7].
When changing the subcutaneous basal insulin infusion rate, a delay in the actual increase or decrease in plasma insulin levels must be anticipated, based on the kinetics of absorption and time to reach a new steady state [8]. Therefore, basal rates of rapid-acting insulin should be changed approximately two hours before the change in plasma insulin level is required.
●Temporary adjustments to basal insulin delivery – Temporary basal rates (nonautomated insulin delivery) and/or temporary higher glucose targets (automated or nonautomated insulin delivery) can also be programmed for defined periods of time. For example, a reduced temporary basal rate can be used to avoid hypoglycemia associated with aerobic activities.
Bolus dosing — The pre-meal bolus dose should be based primarily on the carbohydrate content of the meal and the blood glucose level immediately before the meal. If CGM data are available, use of glucose trends (trend arrows) can help the user fine-tune dosing [9]. (See "Nutritional considerations in type 1 diabetes mellitus", section on 'Advanced carbohydrate counting'.)
●Dosing calculators – Insulin pumps have insulin calculators for bolus dosing both for meals and for correction of hyperglycemia. The use of calculated "active insulin" or "insulin on board" helps prevent hypoglycemia that can occur when multiple correction boluses are administered close together in time ("stacking").
Meals high in fat and protein (eg, steak and potatoes or pizza) can cause a prolonged rise in glucose, requiring a higher insulin dose and longer duration of insulin action [10,11]. Insulin pumps allow for delivery of extended or dual-wave boluses to help manage the prolonged or delayed rise in glucose concentrations that occur after ingesting higher fat and protein meals or in the presence of gastroparesis.
●Timing of dose administration – The timing of preprandial dosing depends on the insulin used. The kinetics of regular insulin require administration approximately 30 to 45 minutes before eating so that the insulin peak matches the peak glucose after the meal. Rapid-acting insulin and faster rapid-acting insulin, which are commonly used in pumps, can be administered 10 to 15 minutes prior to eating; rapid-acting and faster rapid-acting insulins are sometimes given immediately before eating, or even during the meal in specific circumstances (eg, presence of gastroparesis or pre-meal hypoglycemia).
TYPES OF INSULIN PUMPS —
A variety of insulin pumps are available, some of which communicate with specific continuous glucose monitoring (CGM) devices (table 1). The choice among pumps is largely a matter of individual preference, cost, and lifestyle.
When the insulin pump uses an algorithm (based on parameters including CGM results and target glucose) to control basal insulin infusion, the system is termed a partially automated (hybrid) closed-loop system (artificial pancreas or automated insulin delivery [AID]). Some advanced closed-loop systems administer automatic insulin correction doses for hyperglycemia as well. The user must still administer pre-meal bolus insulin (hence the term "hybrid"). For most pumps, dose selection is based on insulin-to-carbohydrate ratios and "correction" factors to address the current glucose level at mealtime. AID systems can reduce time in hypoglycemia and hyperglycemia, and they are generally recommended for people with type 1 diabetes if adequate resources are available to support use. (See 'Insulin only, partially automated systems' below.)
Insulin pumps can be used alone or, preferably, in conjunction with a CGM device. When a pump is used in manual mode with CGM (no automation), the user receives frequent information about their glucose levels, which allows them to make better-informed decisions about insulin dosing. This approach is known as sensor-augmented insulin pump therapy. (See 'Sensor-augmented insulin pump' below.)
Automated insulin delivery systems — AID systems comprise an insulin pump and a CGM device with integrated function, enabling automatic adjustment of insulin delivery based in part on CGM data. Partially automated systems and a more fully automated system for insulin delivery are available for clinical use.
Insulin only, partially automated systems — Several partially automated (hybrid) insulin delivery systems are commercially available in the United States [12-15]. In addition, do-it-yourself (DIY) hybrid systems are used by some individuals and are discussed below. (See 'Do-it-yourself automated insulin delivery systems' below.)
For the first commercial hybrid closed-loop system in the United States, the few available small reports indicated that real-world discontinuation rates were high [16,17]. Improvements have been made in the newer, advanced hybrid closed-loop systems to reduce burden and improve effectiveness and usability, and further advances continue.
Principles of use — When using these insulin pump/CGM systems in the "auto" or "automatic" mode, the system automatically gives a mini-bolus (or no bolus) of rapidly acting insulin every five minutes determined by an algorithm that uses parameters including CGM results and target glucose (figure 1). Automatic correction insulin doses are also provided in advanced hybrid closed-loop systems. In contrast, when these insulin pumps are used for nonautomated insulin delivery ("manual" mode), they infuse basal insulin in mini-boluses every five minutes according to the programmed basal rates. (See 'Basal rate' above and 'Sensor-augmented insulin pump' below.)
With these "hybrid" closed-loop devices, the user still needs to determine and administer pre-meal insulin boluses, which is facilitated with an individualized insulin-to-carbohydrate ratio set in the pump's bolus calculator. One system does not use insulin-to-carbohydrate ratios but instead has the user enter their weight and "announce" their meals with a qualitative description. (See 'More fully automated system' below.)
Older systems require periodic fingerstick capillary glucose measurements for calibration and to address high or low values, and some have limited flexibility for the target glucose. Each of the available devices can transmit insulin dosing data (display of basal and bolus insulin delivery), CGM and blood glucose monitoring (BGM) data, as well as pump and CGM settings to cloud-based systems. These data can be retrieved and reviewed on demand (figure 3A-B and figure 4A-B and figure 5 and figure 6).
Time in target range and hypoglycemia — Partially AID (hybrid closed-loop) systems increase time spent in target glucose range (70 to 180 mg/dL [3.9 to 10 mmol/L]) and reduce A1C compared with sensor-augmented pump therapy without increasing risk of hypoglycemia [18,19]. As an example, in a meta-analysis of trials comparing the use of any hybrid closed-loop system with any insulin-based treatment in nonpregnant adults with type 1 diabetes, the proportion of time spent near normoglycemia (70 to 180 mg/dL [3.9 to 10 mmol/L]) over 24 hours was modestly, albeit significantly, higher with the hybrid closed-loop system (weighted mean difference 9.62 percent, 95% CI 7.54-11 percent) [18]. Overall, the incidence of severe hypoglycemia was low in both groups. Many trials have examined the utility of these devices in the outpatient setting, during eating and usual daily activities, over an extended period of use [12,20-27]. As examples:
●In a crossover, random-order trial, 33 adults (mean A1C 8.5 percent [69.4 mmol/mol]) were assigned to either 12 weeks of partially automated (hybrid), closed-loop insulin delivery (intervention) followed by 12 weeks of sensor-augmented pump therapy (control), or to the opposite order (sensor-augmented pump therapy followed by hybrid, closed-loop insulin delivery) [21]. Participants performed their usual daily activities and were not monitored remotely by study staff.
Compared with the sensor-augmented pump, use of the hybrid closed-loop system resulted in a greater proportion of time spent in the target range of 70 to 180 mg/dL (3.9 to 10 mmol/L; 67.7 versus 56.8 percent, mean difference 11 percentage points, 95% CI 8.1-13.8). The mean glucose level (157 versus 168 mg/dL) and the mean A1C level (7.3 versus 7.6 percent) were also lower during the closed-loop phase of insulin delivery. Hypoglycemia, as measured by the area under the curve when glucose was <63 mg/dL (3.5 mmol/L), was lower during the closed-loop system than during the control period (169 versus 198 [mg/dL x min]).
●In a subsequent six-month trial comparing a hybrid closed-loop system with a sensor-augmented insulin pump in 168 patients ≥14 years of age, the percentage of time in target range (70 to 180 mg/dL [3.9 to 10 mmol/L]) as measured with CGM was higher in the closed-loop group (71 versus 59 percent, risk-adjusted difference 11 percent, 95% CI 9-14) [13]. A1C levels improved in patients using the closed-loop system (7.4 to 7.06 percent) but did not change in controls (7.4 to 7.39 percent). Although there were no serious hypoglycemic events in either group, the percentage of time spent in hypoglycemia was lower in patients assigned to the closed-loop system (eg, <54 mg/dL, 0.29 versus 0.35 percent, risk-adjusted difference -0.10, 95% CI -0.19 to -0.02). There were, however, more hyperglycemic adverse reactions, including one episode of ketoacidosis, in the closed-loop group (14 versus 2 patients), primarily due to infusion set failures. In a similarly designed 16-week trial in children 6 to 13 years of age, the percentage of time in target range was higher with the closed-loop system (67 versus 55 percent, mean adjusted difference 11 percentage points, 95% CI 7-14) [28].
●In a crossover study in 82 older adults (aged 65 to 86 years), including some with mild cognitive impairment, the following insulin delivery strategies were compared: sensor-augmented pump therapy, pump therapy with predictive low glucose suspend, and an advanced hybrid closed-loop system [29]. Both the predictive low glucose suspend and the closed-loop systems reduced hypoglycemia, and the closed-loop system also reduced hyperglycemia. During use of the closed-loop system, mean A1C was 6.9 percent, suggesting that an A1C target of <7 percent may be safely achieved in some older adults with AID systems.
Hybrid closed-loop systems also have been studied in young children (aged <6 years) with type 1 diabetes [30]. The use of AID therapy in children is discussed in detail separately. (See "Type 1 diabetes mellitus in children and adolescents: Insulin therapy", section on 'Initiating insulin pump therapy'.)
Patient selection — Individuals receiving multiple daily injection (MDI) insulin therapy may transition directly to hybrid AID systems without prior insulin pump experience [31], although short-term device training before initiation of AID therapy may be helpful for individuals who have not previously used an insulin pump and/or CGM [32].
Structured and individualized training and support are essential prior to initiation of AID therapy [32]; rather than reducing demands of care, AID therapy requires that individuals and their care partners have extensive knowledge of both general diabetes care and device management. After initiating AID therapy, close monitoring and support remain critical, particularly over the first three to six months of use when discontinuation rates are highest [32].
●Type 1 diabetes – All individuals with type 1 diabetes may be candidates for AID therapy if adequate infrastructure and resources are available to support its use. The strongest evidence supporting use of AID systems is in individuals with high risk of hypoglycemia or impaired awareness of hypoglycemia and individuals who have not achieved glycemic goals on current therapy [32-34]. AID therapy also may provide greater benefit when initiated closer to the time of type 1 diabetes diagnosis.
●Type 2 diabetes – Adults with type 2 diabetes using MDI insulin therapy may be candidates for AID therapy. In the United States, a tubeless AID system has regulatory approval for use in adults with type 2 diabetes. In a nonrandomized trial, use of this AID system was associated with lower A1C values without an increase in hypoglycemia [35].
Two additional AID systems, both of which use the same algorithm, also have regulatory approval for use in adults with type 2 diabetes [36]. In a 13-week trial, 319 adults with type 2 diabetes (mean age 58 years, mean A1C 8.2 percent) were randomly assigned to treatment with AID (n = 215) or their usual insulin delivery strategy (predominantly MDI; n = 104) [37]. AID use led to a greater reduction in mean A1C compared with usual care (-0.9 versus -0.3 percentage points, respectively), and this benefit was evident irrespective of background therapy with other glucose-lowering medications. Time spent in the target glucose range (70 to 180 mg/dL [3.9 to 10 mmol/L]) increased more with AID than with usual care (mean difference 14 percentage points). The rate of hypoglycemic episodes was low in both groups.
More fully automated system — A more fully automated system enables initiation of insulin pump use solely on the basis of user body weight and without input of basal insulin doses or pre--meal or correction insulin dosing parameters. Once initiated, the system automatically calibrates and adjusts insulin delivery based on glycemia. This system requires announcement of meals using qualitative descriptions of carbohydrate intake (eg, "usual for me," "more," or "less" for the specific meal type). In the United States, this more automated system has regulatory approval for use in individuals with type 1 diabetes aged ≥6 years [38].
In a 13-week, unblinded trial in which 219 participants (ages 6 to 79 years, mean age 28 years) with type 1 diabetes (mean A1C approximately 7.8 percent) were randomly assigned to a fully automated insulin system or standard care (any mode of insulin delivery coupled with CGM), the fully automated system conferred a greater reduction in A1C (mean adjusted difference in A1C -0.5 percent, 95% CI -0.6 to -0.3 percent) [15]. The percentage of time spent in target glucose range (≥70 mg/dL and ≤180 mg/dL [3.9 to 10 mmol/L]) was higher with the fully automated insulin system than standard care (mean adjusted difference 11 percent, 95% CI 9-13 percent). Frequency of hypoglycemia was similar between groups.
Sensor-augmented insulin pump — Sensor-augmented insulin pump therapy involves the use of an insulin pump and a CGM device that function independently. Insulin delivery is not automatically adjusted based on CGM readings. A randomized trial compared sensor-augmented insulin pump therapy with MDI insulin therapy using standard BGM without use of CGM in 329 adults [39]. After one year, the reduction in mean A1C was significantly greater in the pump and CGM therapy group (between-group difference -0.6 percentage points). Of note, the design of the study (sensor-augmented pump therapy versus MDI without CGM) could not distinguish between the effects of pump therapy and CGM. (See "Glucose monitoring in the ambulatory management of nonpregnant adults with diabetes mellitus", section on 'CGM systems'.)
Low glucose threshold suspend or predictive low glucose suspend systems — Some insulin pumps can suspend insulin delivery when glucose readings reach a prespecified low glucose threshold or are predicted to reach that threshold.
●Low glucose threshold suspend – These insulin pumps can be programmed to interrupt insulin delivery (for up to two hours) at a preset sensor glucose value (low glucose threshold suspend). The threshold suspend feature reduces the frequency and duration of nocturnal hypoglycemia, as illustrated by the findings from randomized trials [40-42]:
•In one trial, 247 people with type 1 diabetes and nocturnal hypoglycemia (mean age approximately 43 years) were randomly assigned to sensor-augmented insulin pump therapy with or without a threshold suspend feature [40]. After three months, nocturnal hypoglycemia (measured as area under the curve) was significantly lower in the group with the threshold suspend feature (1.5 versus 2.2 events per person per week). Severe hypoglycemia was rare (four episodes), but all events were in the control group.
•In another trial, 95 people with type 1 diabetes and well-documented hypoglycemia unawareness (mean age 18.6 years) were randomly assigned to standard insulin pump (without CGM) or to sensor-augmented insulin pump therapy with a threshold suspend feature [41]. After six months, the rate of severe and moderate hypoglycemic events was significantly lower in the group using the threshold suspend feature (9.5 versus 34.2 events per 100 patient-months). Of note, despite randomization, the baseline frequency of moderate and severe hypoglycemia was substantially greater in the threshold suspend group than the control group, which limits interpretation of the results.
In both trials, there was no significant difference in change in A1C, and there were no episodes of diabetic ketoacidosis (ie, no deterioration of glycemia with brief suspension of insulin delivery). These findings suggest that the threshold suspend feature is useful, and the first trial shows that it can improve the ability of sensor-augmented insulin pump therapy to reduce nocturnal hypoglycemia [40]. The design of the second trial (augmented pump with threshold suspend feature versus standard pump therapy without CGM) could not distinguish between the effects of CGM and a CGM/pump system with threshold suspend feature [41].
●Predictive low glucose suspend – Some insulin pumps are available with a "predictive low glucose suspend" feature. In contrast to low glucose threshold suspend, in which insulin delivery is suspended when the glucose reading reaches the threshold value (eg, 70 mg/dL [3.9 mmol/L]), predictive low glucose threshold suspend reduces or suspends insulin infusion when the trend in CGM results predicts that hypoglycemia will occur. In randomized trials of predicative low glucose suspend in children and adults, using different devices, there was a reduction of hypoglycemia without an increase in hyperglycemia [43-45].
Do-it-yourself automated insulin delivery systems — The use of do-it-yourself automated insulin delivery (DIY AID) systems or "looping" by individuals with type 1 diabetes to automatically infuse insulin has increased in the United States and globally. The systems use commercially available insulin pumps and CGM devices, smartphones, and applications that control insulin infusion. Additional hardware and communication devices may be needed. Free open-source resources for each of the available DIY looping systems are offered on their websites, including the Tidepool Loop insulin dosing app, which has regulatory approval in the United States. All of these systems involve a high degree of involvement by the person with diabetes.
Limited clinical trial data support the utility of open-source AID systems for selected individuals willing to learn these systems. As an example, in a 24-week trial comparing an open-source DIY AID system with sensor-augmented insulin pump therapy in 97 people with type 1 diabetes (48 children [median age 13 years] and 49 adults [median age 40 years]), the improvement in percentage of time spent in target glucose range was greater in participants using the open-source AID system (adjusted difference 14 percent, 95% CI 9.2-18.8 percent) [46]. All participants underwent a four-week run-in period before randomization to gain experience with the study devices, and all had at least six months' prior experience using an insulin pump. Since the design of this study did not incorporate a comparison of the open-source non-FDA approved DIY AID system with a currently commercially available FDA-approved AID (hybrid closed-loop) system, it could not compare their safety or effectiveness.
FOLLOW-UP VISITS —
As in adults with type 1 diabetes treated with multiple daily injection (MDI) insulin therapy, the frequency of clinic visits and adjustments to the insulin regimen vary based on individual needs. This information is reviewed in detail separately. (See "Management of blood glucose in adults with type 1 diabetes mellitus", section on 'Follow-up'.)
SAFETY CONSIDERATIONS
Pump failure
●Causes of apparent pump failure – Pump failure may occur due to mechanical failure or detachment, blockage-kinking, or leakage in the infusion set/cannula, syringe, or connectors, causing an interruption of insulin flow [47-49]. The pump may be in suspension mode or may need a battery change. Air in the infusion set may cause reduced insulin delivery in the absence of true pump failure. Use of expired or damaged insulin (exposure to high temperatures or freezing) will also present as pump failure. A poor infusion site can impede insulin delivery; infusion sites may not absorb insulin well due to overuse, scarring, or lipohypertrophy [50].
●Acute management – Since the subcutaneous depot is very small and only rapidly acting insulin is administered, any interruption in continuous flow can lead very quickly to hypoinsulinemia and potentially diabetic ketoacidosis. If there is no glucose response to insulin boluses, the infusion set should be immediately changed and a new insertion site chosen. Failure of insulin delivery despite these actions usually indicates pump failure.
If pump failure occurs, individuals can replace basal insulin with rapidly acting insulin injections every three to four hours (each dose equivalent to three to four times the hourly basal rate) with careful, frequent blood glucose monitoring (BGM) or continuous glucose monitoring (CGM). If the anticipated interruption in pump therapy is more than a few hours, individuals should transition to an intermediate-acting or long-acting basal insulin to replace the basal infusion. Using the total daily basal insulin dose as a guide, a similar dose can be given as one or two injections of glargine or divided into two injections of NPH daily. In this setting, we do not use basal insulin with a very long duration of action such as insulin degludec, as it takes approximately four days to reach steady state. When restarting pump therapy, if there is residual basal insulin on board, a lower temporary basal rate may be needed until the intermediate-acting or long-acting insulin effect has dissipated.
●Prevention and precautions – If problems with infusion sets recur, the individual's insertion technique should be reviewed. A different type of infusion set (eg, metal needle instead of Teflon catheter) can be considered. All pump users should know how to check for ketones (either blood or urine) and have a back-up plan for both basal and mealtime insulin (ie, insulin vials and syringes or insulin pens) to use in the event of pump failure.
Superficial infection — Adults who are treated with continuous subcutaneous insulin infusion (CSII) may rarely develop infections at the site of catheter insertion. This is more likely to occur if the infusion set has not been changed for >72 hours, if the site was not properly prepared, or if the infusion set was not properly inserted. If the infusion site is red, swollen, painful, draining purulent material, or has increased warmth, the infusion set should be immediately removed and discarded and a new set placed at another site. The old site should be cleaned and treated with warm soaks; occasionally, oral antibiotic therapy is needed.
NPO for procedures — If meeting their glycemic goals, people with type 1 diabetes who are using a nonautomated insulin delivery system (eg, sensor-augmented insulin pump) and are not eating (nil per os [NPO]) in preparation for a procedure may continue with their usual basal infusion rate. Depending on overall glycemia before the procedure, the length of the procedure, and degree of concern about hypoglycemia, the basal rate may be reduced by up to 20 percent for at least two to three hours pre-procedure or once the individual becomes NPO to minimize the risk of hypoglycemia.
People using automated insulin delivery (AID) systems who are concerned about hypoglycemia while NPO may instead set a temporary, higher target glucose (or target glucose range) prior to a procedure; the methods for adjusting the target glucose vary across AID systems and can include the use of an "exercise" or "activity" mode. More information about device management can be found through the PANTHER program.
No routine insulin boluses should be administered until the individual can eat. The management of insulin therapy (including use of insulin delivery systems) during and after surgical procedures is reviewed separately. (See "Perioperative management of blood glucose in adults with diabetes mellitus", section on 'Glucose management'.)
Privacy and cybersecurity — The wireless communication between glucose monitoring devices and insulin pumps allows for the possible interception of data and control of insulin delivery by unauthorized individuals [49,51]. People with diabetes who use these devices should be cautioned about these risks. They further should be counseled to avoid linking their devices in public settings and to disable the remote bolus feature of the insulin pump if present [51].
Falsely low CGM glucose readings due to compression — Falsely low continuous glucose monitoring (CGM) readings can occur from tissue compression (eg, sleeping on the sensor). If this occurs during use of an AID system, this "compression low" can aberrantly alert the pump to reduce insulin delivery. In this setting, a sudden drop in glucose is usually apparent on CGM (the falsely low value), followed by a quick recovery after the person changes position. If a falsely low CGM value is suspected, the user should check a fingerstick glucose reading.
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Diabetes mellitus in adults" and "Society guideline links: Blood glucose monitoring".)
SUMMARY AND RECOMMENDATIONS
●General principles – With continuous subcutaneous insulin infusion (CSII; insulin pump therapy), basal insulin is supplied in the form of mini-boluses of insulin delivered every five minutes (usually constituting 40 to 50 percent of the total daily dose [TDD]) with pre-meal bolus doses given to minimize postprandial glucose excursions. We suggest rapid-acting insulin analogs (lispro, aspart, and glulisine) rather than regular insulin for insulin pump therapy (Grade 2C). (See 'General principles' above.)
●Dosing
•TDD – For individuals meeting glycemic goals who are transitioning from a multiple daily injection (MDI) insulin regimen to CSII, the initial TDD (both short-acting and long-acting insulin) of insulin administered by pump may be 10 to 20 percent less than the TDD of the MDI regimen. Conversely, people who are above glycemic targets and without hypoglycemia) may be started with the same TDD as they had been using with their injection regimens. (See 'Total daily dose' above.)
•Basal rate – Approximately 40 to 50 percent of the TDD is administered as the basal rate (divide by 24 to get units per hour). This proportion can be higher or lower depending on a number of factors, including if the individual consumes a low- or high-carbohydrate diet, respectively. For most individuals, basal rates are in the range of 0.01 to 0.015 units per kg per hour (ie, for a 60 kg adult approximately 0.6 to 0.9 units per hour). (See 'Basal rate' above.)
For people using automated insulin delivery (AID) systems, basal rate settings dictate insulin delivery only when the insulin pump is used in a nonautomated mode (ie, "manual" mode).
•Bolus dosing – The pre-meal bolus dose should be based primarily on the carbohydrate content of the intended meal and the blood glucose level immediately before the meal. Many insulin pumps have insulin calculators for bolus dosing for meals and for correction of hyperglycemia. Extended or dual-wave boluses can be used to help manage the prolonged or delayed rise in glucose that is commonly observed after eating higher fat and protein meals or in the presence of gastroparesis. The use of calculated "active insulin" or "insulin on board" helps prevent hypoglycemia that can occur from overcorrecting for hyperglycemia with multiple correction boluses ("stacking"). (See 'Bolus dosing' above.)
●Types of insulin pumps – A variety of insulin pumps are available, and the choice among pumps is largely a matter of individual preference, cost, lifestyle, and compatibility with continuous glucose monitoring (CGM) devices (figure 1 and figure 2). Use of hybrid closed-loop systems can reduce time in hypoglycemia. (See 'Types of insulin pumps' above.)
•Automated insulin delivery (AID) systems – These systems comprise an insulin pump and a CGM device with integrated function. When partially automated insulin delivery systems are in the "auto" or "automatic" mode, the system automatically gives a mini-bolus (or no bolus) of rapidly acting insulin every five minutes determined by an algorithm that uses parameters including CGM results and target glucose (figure 1 and figure 3B and figure 5). Automatic correction insulin doses are also provided in advanced hybrid closed-loop systems. With these "hybrid" closed-loop devices, the user still needs to determine and administer pre-meal insulin boluses. With a more fully automated system, insulin pump use can be initiated solely on the basis of user body weight. Once initiated, the system automatically calibrates and adjusts insulin delivery based on glycemia. (See 'Insulin only, partially automated systems' above and 'More fully automated system' above.)
•Sensor-augmented insulin pump – Sensor-augmented insulin pump therapy involves the use of an insulin pump and a CGM device that function independently. (See 'Sensor-augmented insulin pump' above.)
•Low glucose threshold suspend or predictive low glucose suspend systems – Some insulin pumps can suspend insulin delivery when glucose readings reach a prespecified low glucose threshold or are predicted to reach that threshold. (See 'Low glucose threshold suspend or predictive low glucose suspend systems' above.)
●Follow-up visits – The frequency of clinic visits and adjustments to the insulin regimen vary based on the needs of the person with diabetes. (See "Management of blood glucose in adults with type 1 diabetes mellitus", section on 'Follow-up'.)
