Interactive diabetes case 9: Management of type 1 diabetes in a patient on glucocorticoid therapy

CASE — A 38-year-old woman, whom you have treated for type 1 diabetes for many years, comes in for an urgent office visit because her blood glucose values have risen markedly in the last few days. One week ago, she was started by her allergist on prednisone 60 mg every morning for asthma not responsive to conservative therapy including an inhaled glucocorticoid. She responded well with a marked reduction in symptoms, improvement in the peak expiratory flow rate, and improved exercise tolerance.

The patient has had diabetes since age 17 years, complicated by proliferative retinopathy previously treated with laser therapy, nephropathy with microalbuminuria and hypertension, and distal sensory neuropathy. She is treated with NPH insulin 14 units and regular insulin 8 units before breakfast, regular insulin 10 units before supper, and NPH insulin 6 units at bedtime. Since the development of proliferative retinopathy with impaired vision in the left eye four years ago, she has been very attentive to management of her diabetes. She checks her blood glucose level four times a day and brings a printout of her glucometer readings to each office visit. Her current 15-day blood glucose average is 181 mg/dL (10 mmol/L); the 30-day average is 142 mg/dL (7.9 mmol/L). The table shows blood glucose values (mg/dL) before and after the start of prednisone  (table 1).

The most recent glycated hemoglobin (A1C), obtained three weeks before the start of prednisone, was 6.9 percent.

Physical examination reveals an anxious woman who is in no acute distress. Blood pressure is 145/90 mmHg right arm supine, 140/95 mmHg right arm upright, heart rate 84 bpm regular, weight 126 pounds, height 5' 1", body mass index (BMI) 23.8 kg/m². The right fundus reveals evidence of previous photocoagulation therapy but no fresh hemorrhages or neovascular changes. The left fundus is similar but also reveals cicatrix formation inferior to the nerve head. The chest examination reveals scattered expiratory wheezes in all fields but no prolongation of expiration. Cardiac examination is within normal limits. The dorsal pedal pulses are absent bilaterally. The right posterior tibial pulse is 2+, the left is absent. Sensation to light touch is absent to the tibial tubercles. Vibratory sensation is absent at the great toes, markedly reduced at the medial malleoli, and nearly normal at the tibial tubercles. Knee jerks and ankle jerks are absent bilaterally.

The patient's medications, other than insulin, are lisinopril 10 mg once a day; aspirin 81 mg a day; fluticasone-salmeterol 250 mcg/50 mcg, one inhalation twice a day; albuterol inhaler two puffs every four hours as needed; and montelukast 10 mg once a day.

How would you manage the patient's diabetes at this time?

●You add metformin 1000 mg twice a day with meals to reduce hepatic glucose output. (See "Interactive diabetes case 9: Management of type 1 diabetes in a patient on glucocorticoid therapy – A1".)

●You discuss with the patient and the allergist the expected duration of systemic glucocorticoid therapy before proceeding further. (See "Interactive diabetes case 9: Management of type 1 diabetes in a patient on glucocorticoid therapy – A2".)

●You increase the dose of NPH insulin to 20 units before breakfast and 10 units at bedtime. You add to the current doses of regular insulin before breakfast and supper an insulin correction factor before meals and at bedtime using a generous correction factor of 20, ie, one unit of short-acting (regular) insulin for every 20 mg/dL (1.1 mmol/L) elevation of the blood glucose level above a reference point of 120 mg/dL (6.7 mmol/L), approximately twice the correction factor one might otherwise use. (Based on the patient's insulin doses before the start of prednisone and using the rule of 1500, the correction factor would otherwise be 39.5). An approach to estimating the dose of short- and very short-acting insulins is discussed separately (see "Interactive diabetes case 3: Hypoglycemia in a patient with type 1 diabetes – B2"). You anticipate further adjustment of the new insulin regimen as the patient monitors the blood glucose values on it and as the dose of prednisone is tapered. (See "Interactive diabetes case 9: Management of type 1 diabetes in a patient on glucocorticoid therapy – A3".)

●You admit the patient to the hospital for an intravenous insulin infusion to control the hyperglycemia rapidly and then to adjust the patient's daily insulin regimen. (See "Interactive diabetes case 9: Management of type 1 diabetes in a patient on glucocorticoid therapy – A4".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Type 1 diabetes (The Basics)" and "Patient education: Using insulin (The Basics)")

●Beyond the Basics topics (see "Patient education: Type 1 diabetes: Overview (Beyond the Basics)" and "Patient education: Glucose monitoring in diabetes (Beyond the Basics)" and "Patient education: Type 1 diabetes: Insulin treatment (Beyond the Basics)" and "Patient education: Preventing complications from diabetes (Beyond the Basics)")