Patient education: Type 2 diabetes and diet (Beyond the Basics)

TYPE 2 DIABETES OVERVIEW — 

Type 2 diabetes mellitus is a disorder that disrupts the way your body uses glucose (sugar). It also causes other problems with the way your body stores and processes other forms of energy, including fat.

All the cells in your body need sugar to work normally. Sugar gets into the cells with the help of a hormone called insulin. In type 2 diabetes, the body stops responding to normal or even high levels of insulin, and over time, the pancreas (an organ in the abdomen) does not make enough insulin to keep up with what the body needs. Having excess body weight, especially when extra fat is stored in the liver and abdomen, increases the body's demand for insulin. If insulin production cannot meet this demand, sugar levels in the bloodstream rise, which can lead to problems if untreated.

People with type 2 diabetes require regular monitoring and ongoing treatment to maintain goal blood sugar levels. Treatment includes lifestyle adjustments, self-care measures, and medications; combined, these approaches can help reduce the risk of complications. Learning to manage diabetes is a process that continues over a lifetime.

This topic review discusses the role of diet in the management of type 2 diabetes. Separate topic reviews about other aspects of type 2 diabetes are also available. (See "Patient education: Type 2 diabetes: Overview (Beyond the Basics)" and "Patient education: Type 2 diabetes: Treatment (Beyond the Basics)" and "Patient education: Type 2 diabetes: Insulin treatment (Beyond the Basics)" and "Patient education: Glucose monitoring in diabetes (Beyond the Basics)" and "Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)" and "Patient education: Exercise and medical care for people with type 2 diabetes (Beyond the Basics)" and "Patient education: Preventing complications from diabetes (Beyond the Basics)".)

WHY IS DIET IMPORTANT? — 

Making changes to your diet is a key part of managing type 2 diabetes.

You may have heard of the "ABCs of diabetes." This refers to three aspects of your health that should be well-managed in diabetes care: A1C (a blood test that measures your average blood sugar level over the past few months), Blood pressure, and Cholesterol. Keeping your blood sugar at or near your goal level helps decrease the risk of complications that can affect the eyes, kidneys, and nerves. Keeping your blood pressure and cholesterol levels at goal helps reduce your risk of cardiovascular (heart) disease, which is a common complication of type 2 diabetes. (See "Patient education: High blood pressure, diet, and weight (Beyond the Basics)" and "Patient education: High cholesterol and lipids (Beyond the Basics)".)

Many factors affect how well a person's diabetes is managed. You can reduce your risk of complications by following your health care provider's guidance around diet, exercise, blood sugar monitoring, and medication regimens. Dietary changes are typically focused on eating nutritious foods and achieving (and maintaining) a healthy body weight. If you take insulin, you may also need to be consistent about what you eat and when.

Finding an optimal diet for diabetes management can be challenging. It can help to work with a dietitian to create a plan that is tailored to your specific situation (including what diabetes medications you take), lifestyle, and personal preferences.

TYPE 2 DIABETES, DIET, AND WEIGHT — 

If you have overweight or obesity, reducing body weight can improve blood sugar management and lower your blood pressure and cholesterol levels.

Reducing body weight — Your health care provider can help you set goals for reducing body weight. For a person who has overweight or obesity, a typical goal is to lose 5 to 10 percent of their body weight. For a person who weighs 240 pounds, this would mean losing 12 to 24 pounds. Losing even more weight can sometimes reduce blood sugar to the normal range. If you no longer need any medications to keep your blood sugar levels in the normal range, this is called "diabetes remission." Diabetes remission is more likely to occur if you have had diabetes for less than six years and are not taking insulin. But even losing a little bit of weight can help improve your health; in fact, cutting back on the number of calories you eat each day can lower your blood sugar levels even before you actually lose weight.

The initial approach to weight loss usually involves eating fewer calories and exercising regularly. Other strategies may be appropriate for some people, including medications and surgery. More information about reducing body weight is available separately. (See "Patient education: Losing weight (Beyond the Basics)".)

Recommended calorie intake — The number of calories you need to maintain your current weight depends upon your age, sex, height, weight, and activity level. Below are some general guidelines:

●Men, active women – 15 calories per pound

●Most women, sedentary men, and adults over 55 years of age – 13 calories per pound

●Sedentary women, adults with obesity – 10 calories per pound

●Pregnant, lactating women – 15 to 17 calories per pound

To lose 1 to 2 pounds per week (which is considered a safe rate of weight loss), you can subtract 500 to 1000 calories from the total number of calories needed to maintain body weight.

As an example, a sedentary man with obesity who weighs 250 pounds would need to eat 10 calories per pound, which totals 2500 calories, per day to maintain his weight. To lose 1 to 2 pounds per week, he should reduce his intake to 1500 to 2000 calories per day. As you lose weight, you will need to adjust your daily recommended calorie intake accordingly.

Avoiding weight gain — Some treatments for type 2 diabetes, such as intensive insulin therapy and certain oral medications, can contribute to weight gain. The following tips can help you avoid unwanted weight gain:

●Weigh yourself on a regular basis (eg, every morning). If your body weight increases more than 2 to 3 pounds in a week, try decreasing the number of calories you eat or increasing the amount of physical activity you do. Taking early action can help avoid greater challenges for body weight reduction.

●As your blood sugar management improves with treatment, it may be necessary to decrease your daily calorie intake to avoid weight gain.

●If your blood sugar levels are frequently low at a particular time of day, your provider might suggest decreasing your dose of insulin or other medication rather than adding a snack at that time. This can help avoid increases in body weight due to diabetes medications.

Exercise — Getting regular physical activity is very important for good health. Exercise makes the body more sensitive to insulin (the hormone that allows cells in the body to take up sugar for energy), which helps lower blood sugar levels. Exercise can also help reduce blood pressure and improve cholesterol levels. Other important benefits of exercise may include maintaining a healthy body weight, reducing body weight (if needed), and improving memory, sleep, and mood.

Exercise for people with type 2 diabetes is discussed in more detail separately. (See "Patient education: Exercise and medical care for people with type 2 diabetes (Beyond the Basics)", section on 'Exercise and type 2 diabetes'.)

TYPE 2 DIABETES AND CARBOHYDRATE CONSISTENCY — 

Carbohydrates are the main energy source in the diet and include starches, vegetables, fruits, dairy products, and sugars. Most meats and fats do not contain any carbohydrates.

Carbohydrates directly affect your blood sugar level, whereas proteins and fat have little impact. Eating a consistent amount of carbohydrates at each meal can help to control your blood sugar levels, especially if you take certain oral diabetes medications or long-acting insulin.

There are different ways to make sure you eat a consistent amount of carbohydrates day to day, including carbohydrate counting, exchange planning, and the "plate method."

Carbohydrate counting — A dietitian can help you figure out the number of carbohydrates you need each day based on your eating habits, weight, nutritional goals, and activity level. The way carbohydrates are divided up for each meal or snack will depend on your personal preferences, the timing and spacing of your meals, and which diabetes medications you take (table 1). "Carb counting" is particularly important if you take insulin, as you will need to adjust your insulin doses according to the carbohydrate content of what you are planning to eat. However, even if you do not take insulin, carb counting can help you learn your personal blood sugar response to varying amounts of carbohydrate at meals and snacks. This can help you keep your blood sugar levels from getting too low or too high.

The number of carbohydrates in a particular food can be determined by reading the nutrition label, consulting a reference book, website, or smartphone app, or using the exchange system (see 'Exchange planning' below). If you are eating out, restaurants usually have this information available upon request. (See 'Where to get more information' below.)

If you are calculating the carbohydrate content of a food, it is also important to note:

●The serving size – Eating more than one serving will increase the number of calories and carbohydrates consumed and the dose of insulin needed to cover the meal (if you take insulin). For example, some prepackaged snacks contain two or more servings. To calculate the carbohydrate content of the entire package, multiply the number of servings by the number of carbohydrates per serving.

●The fiber content – When a serving of food has more than 5 grams of fiber, subtract the grams of fiber from the grams of carbohydrates to calculate your insulin dose (figure 1). This is because fiber is not absorbed into the bloodstream; it also slows the body's absorption of carbohydrates, so less insulin is required to manage blood sugar levels.

Exchange planning — With exchange planning, all foods are categorized as either a carbohydrate, meat or meat substitute, or fat. In this system, one serving of a carbohydrate (eg, one small apple) can be exchanged for any other carbohydrate (eg, 1/3 cup cooked pasta) because both portions contain about 15 grams of carbohydrate. You can also easily determine the carbohydrate content of your meals and snacks using the exchange system. The table shows a sample daily meal plan based on this system (table 2). A dietitian can give you a more complete list of foods to use for meal planning purposes.

The exchange lists also identify foods that are good sources of fiber (which can help keep blood sugar levels from getting too high) and foods with a lot of sodium (which should be limited). A dietitian can help you determine how many servings of each group to eat at each meal and snack (table 2) and the typical carbohydrate content of each meal and snack.

Plate method — With the plate method, based on a 9-inch diameter plate, foods are portioned as follows: one-half plate as nonstarchy vegetables, one-quarter plate as lean protein, and one-quarter plate for carbohydrates such as starches or grains. Using the plate method can help achieve carbohydrate consistency, as well as help manage total calorie intake.

Meal timing — Consistently eating at the same times every day is important for some people, especially those who take long-acting insulin or oral medications that decrease blood sugar levels (for example, sulfonylureas like glipizide or glimepiride, or meglitinides like repaglinide). If a meal is skipped or delayed while on these regimens, you are at risk for developing low blood glucose.

If you use "intensive" insulin therapy (ie, if you give yourself multiple daily injections or use an insulin pump) or take certain other types of oral diabetes medications (eg, metformin), you may have more flexibility around meal timing. With these regimens, skipping or delaying a meal will not usually increase your risk of low blood sugar.

While foods that are high in fat (eg, pizza) are OK to eat occasionally, you will need to monitor your blood sugar levels more closely. High-fat, high-protein meals are broken down more slowly than low-fat, lower-protein meals. When using rapid-acting insulin before a meal, your blood sugar level may become low shortly after eating a high-fat meal and then rise hours later. If you eat meals that contain more protein or fat than usual, you may need to make meal-time insulin dose adjustments to manage this delayed rise in blood sugar.

Intensive insulin therapy — If you take multiple injections of insulin per day or use an insulin pump, you can adjust your pre-meal insulin based on the number of carbohydrates you plan to eat and your pre-meal blood sugar, similar to patients with type 1 diabetes. (See "Patient education: Type 1 diabetes and diet (Beyond the Basics)", section on 'Intensive insulin therapy'.)

WHAT SHOULD I EAT? — 

There is not a single optimal diet or meal plan for people with diabetes. The best diet for you depends on many different things, including your health concerns, weight-loss goals, and personal preferences.

General recommendations — To help manage the ABCs (A1C, Blood pressure, and Cholesterol) and promote good health, experts recommend that all people with diabetes aim to maintain a healthy body weight (by decreasing calorie intake and increasing physical activity) and monitor their carbohydrate intake. The following guidelines for a healthy diet are similar to the recommendations for adults without diabetes (see "Patient education: Diet and health (Beyond the Basics)"):

●A diet that includes carbohydrates from fruits, vegetables, whole grains, legumes, and low-fat milk is encouraged. People with diabetes are advised to avoid sugary beverages (including natural fruit juice).

The ideal amount of carbohydrate intake is uncertain. However, it's important for people with diabetes to monitor carbohydrate intake in order to manage their blood sugar levels and adjust insulin dosing as needed. (See 'Carbohydrate counting' above.)

●In general, a variety of eating patterns (low fat, low carbohydrate, Mediterranean, vegetarian) are acceptable. Eating a healthy diet that contains a lot of the foods you like will make it easier to stick to your plan. However, you should talk to your health care provider before starting any diet that involves extreme restriction (such as a very low carb or "keto" diet). Depending on your situation, some diets may not be recommended.

●The type of fat consumed appears to be more important than the amount of total fat. Saturated fats (eg, in meats, cheese, ice cream) can be replaced with monounsaturated and polyunsaturated fatty acids (eg, in fish, olive oil, nuts). Trans fatty acid consumption should be kept as low as possible. Trans fats are banned from processed foods in the United States. Although very small amounts of trans fats are naturally present in meats, poultry and dairy products, the amount is too small for concern.

As diabetes increases your risk of heart disease and stroke, eating a diet low in saturated and trans fats and cholesterol can help to reduce your cholesterol levels and decrease these risks.

●A dietitian can help you to determine how much protein your diet should include. In general, it's a good idea to get protein from lean meats, fish, eggs, beans, soy, and nuts, and to limit the amount of red meat you eat.

●Eating a diet that is high in fiber may help you manage your blood sugar levels. (See "Patient education: High-fiber diet (Beyond the Basics)".)

●A diet that is low in sodium and high in fruits, vegetables, and low-fat dairy products can help manage blood pressure. (See "Patient education: Low-sodium diet (Beyond the Basics)".)

●Artificial sweeteners do not affect blood glucose levels and may be consumed in moderation if they help reduce your overall calorie and carbohydrate intake. If you consume sugar-sweetened beverages regularly, a beverage containing artificial sweeteners (such as diet soda) can be a good short-term replacement strategy. However, the best approach is to avoid both sugar-sweetened and artificially sweetened beverages and try to drink more water.

●In the past, people with diabetes were told to avoid all foods with added sugar. This is no longer recommended, although it's important to limit sugar intake. If you take insulin, you should calculate each pre-meal dose based upon the total number of carbohydrates in the food, which includes the sugar content. (See 'Carbohydrate counting' above.)

●Products that are "sugar-free" or "fat-free" do not necessarily have a reduced number of calories or carbohydrates. Read all nutrition labels carefully and compare with other similar products to determine which has the best balance of serving size and number of calories, carbohydrates, fat, and fiber.

Some sugar-free foods, such as sugar-free gelatin and sugar-free gum, do not have a significant number of calories or carbohydrates and are considered "free foods." Any food that has less than 20 calories and 5 grams of carbohydrate is considered a free food, meaning that it does not affect body weight or require an adjustment to your medication.

The American Diabetes Association (ADA) has a website called Diabetes Food Hub (www.diabetesfoodhub.org) that many people find useful. The site has tools to help you manage your diabetes, including nutrition information and customizable recipes you can use in meal planning.

It can be challenging and sometimes overwhelming to figure out how to manage your diet if you have diabetes. But with time, practice, and support, this can become an easier part of daily life.

Is it safe to drink alcohol? — Drinking a moderate amount of alcohol (up to one serving per day for women or two servings per day for men) with food does not affect blood sugar levels significantly. People who take oral diabetes medications do not usually need to adjust their medication doses, as long as the alcohol is consumed in moderation and with food. Alcohol may cause a slight rise in blood sugar, followed hours later by a decrease in the blood sugar level. As a result, it is important to monitor your blood sugar response to alcohol, especially if you use insulin. Your provider can help you to determine if any changes in insulin doses are needed.

Mixers, such as fruit juice or regular cola, can increase blood sugar levels and increase the number of calories consumed in a day. Also, calories from alcohol have little nutritional value and may contribute to weight gain (or make it harder to lose weight).

WHERE TO GET MORE INFORMATION — 

Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces 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.

Patient education: Type 2 diabetes (The Basics)
Patient education: Diabetes and diet (The Basics)
Patient education: Diet and health (The Basics)
Patient education: High-fiber diet (The Basics)
Patient education: Carb counting for adults with diabetes (The Basics)
Patient education: Treatment for type 2 diabetes (The Basics)
Patient education: The ABCs of diabetes (The Basics)
Patient education: Preparing for pregnancy when you have diabetes (The Basics)
Patient education: Lowering your risk of prediabetes and type 2 diabetes (The Basics)
Patient education: Diabetes and heart disease (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: High blood pressure, diet, and weight (Beyond the Basics)
Patient education: High cholesterol and lipids (Beyond the Basics)
Patient education: Type 2 diabetes: Overview (Beyond the Basics)
Patient education: Type 2 diabetes: Insulin treatment (Beyond the Basics)
Patient education: Glucose monitoring in diabetes (Beyond the Basics)
Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)
Patient education: Exercise and medical care for people with type 2 diabetes (Beyond the Basics)
Patient education: Preventing complications from diabetes (Beyond the Basics)
Patient education: Losing weight (Beyond the Basics)
Patient education: Exercise (Beyond the Basics)
Patient education: Chronic kidney disease (Beyond the Basics)
Patient education: High-fiber diet (Beyond the Basics)
Patient education: Low-sodium diet (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Alpha-glucosidase inhibitors for treatment of diabetes mellitus
Exercise guidance in adults with diabetes mellitus
Measurements of chronic glycemia in diabetes mellitus
Glycemic management and vascular complications in type 2 diabetes mellitus
Initial management of hyperglycemia in adults with type 2 diabetes mellitus
Insulin therapy in type 2 diabetes mellitus
Management of persistent hyperglycemia in type 2 diabetes mellitus
Metformin in the treatment of adults with type 2 diabetes mellitus
Medical nutrition therapy for type 2 diabetes mellitus
Overview of general medical care in nonpregnant adults with diabetes mellitus
Sulfonylureas and meglitinides in the treatment of type 2 diabetes mellitus
Thiazolidinediones in the treatment of type 2 diabetes mellitus

The following organizations also provide reliable health information.

●National Library of Medicine

(www.nlm.nih.gov/medlineplus/healthtopics.html)

●National Institute of Diabetes & Digestive & Kidney Diseases

(www.niddk.nih.gov)

●American Diabetes Association (ADA)

(www.diabetes.org)

●The Endocrine Society

(www.endo-society.org)

●Hormone Health Network

(www.hormone.org, available in English and Spanish)

The following reference books are a good source of information regarding diabetes, diet, carbohydrate counting, and how to lose weight to manage diabetes.

●The Doctor's Pocket Calorie, Fat, and Carb Counter, Allan Borushek, also available for download to personal digital assistant at www.calorieking.com

●Practical Carbohydrate Counting, Hope Warshaw and Karmeen Kulkarni

●Beating Diabetes: Lower Your Blood Sugar, Lose Weight, and Stop Diabetes and Its Complications in Their Tracks, David Nathan and Linda Delahanty

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