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TYPE 2 DIABETES OVERVIEW — Type 2 diabetes mellitus is a disorder that is known for disrupting 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. Being overweight, especially having extra fat stored in the liver and abdomen, increases the body's demand for insulin. This causes sugar to build up in the blood, 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: Blood glucose monitoring in diabetes (Beyond the Basics)" and "Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)" and "Patient education: Type 2 diabetes: Alcohol, exercise, and medical care (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-controlled in order to manage your diabetes: 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 under control 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 controlled. 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 getting to (and maintaining) a healthy weight. If you take insulin, you may also need to be consistent about what you eat and when.
Having to pay careful attention to your diet 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 are overweight or obese, losing weight can improve blood sugar control and lower your blood pressure and cholesterol levels.
Losing weight — Your health care provider can help you set goals for losing weight. For a person who is overweight or obese, 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 the blood sugars to the normal range. 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. There are other strategies that may be appropriate for people who are having trouble losing weight, including medications and surgery. More information about losing 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 – 13 calories per pound
●Sedentary women, obese adults – 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 weight.
As an example, an obese, sedentary man 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 you gain 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. Do not wait until you have gained a larger amount of weight, as this will make it harder to lose.
●As your blood sugar control improves with treatment, it may be necessary to somewhat 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.
Exercise — Exercising regularly can help to lose weight and keep it off. Exercise has other health benefits, too. The recommended amount of exercise for most people is 30 minutes per day most days of the week. (See "Patient education: Exercise (Beyond the Basics)".)
If you take insulin or oral medications that lower blood sugar levels, you will need check your blood sugar level before and after exercising. If you are doing a new exercise routine that is vigorous and prolonged (more than 30 minutes), and you expect to do the same routine again in the future, check your blood sugar every 15 minutes. This can help give you a sense of how exercise affects your blood sugar level.
If your blood sugar level becomes low during exercise, eat a snack according to the guidelines below. (See "Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)".)
●If the blood glucose is 51 to 70 mg/dL (2.8 to 3.8 mmol/L), eat 10 to 15 grams of fast-acting carbohydrate (eg, 1/2 cup fruit juice, six to eight hard candies, three to four glucose tablets).
●If the level is less than 50 mg/dL (2.7 mmol/L), eat 20 to 30 grams of fast-acting carbohydrates.
●If you are not able to check your blood sugar but you have symptoms of hypoglycemia (eg, sweating and shaking), eat 10 to 15 grams of fast-acting carbohydrate.
Retest after 15 minutes and repeat treatment if blood glucose is still too low. If your next meal is more than an hour away, eat an additional 15 grams of carbohydrate and 1 ounce of protein (for example, crackers with cheese or one-half of a sandwich with peanut butter). It is important not to eat too much, because this can raise your blood sugar level too much and lead to weight gain over the long term.
Adjusting insulin dose for exercise — If you take oral diabetes medications, you probably will not need to adjust the dose of these medications for exercise.
If you take insulin, it may be possible to reduce your insulin dose before exercising to avoid developing low blood glucose. A physician, diabetes educator, dietitian, or exercise physiologist can help to determine the best way to adjust your insulin dose before, during, and after exercising. (See "Patient education: Type 2 diabetes: Insulin treatment (Beyond the Basics)".)
TYPE 2 DIABETES AND 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 glucose levels significantly. Alcohol may cause a slight rise in blood glucose, followed hours later by a decrease in the blood glucose level. As a result, it is important to monitor blood glucose response to alcohol to determine if any changes in insulin doses are needed.
Mixers, such as fruit juice or regular cola, can increase blood glucose 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). If you take oral diabetes medications, you will not need to adjust your medication, as long as you drink the alcohol in moderation and with food.
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 throughout the day, including carbohydrate counting and exchange planning.
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 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 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.
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 (sulfonylureas or meglitinides). 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 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 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 sugar-sweetened beverages (including 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 to keep your blood sugar levels under control. (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 keep blood pressure under control. (See "Patient education: Low-sodium diet (Beyond the Basics)".)
●Artificial sweeteners do not affect blood glucose levels and may be consumed in moderation. 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 in order to control your diabetes. But with time, practice, and support, most people are able to get used to it and make it a part of their daily life.
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: Preventing type 2 diabetes (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: Blood glucose monitoring in diabetes (Beyond the Basics)
Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)
Patient education: Type 2 diabetes: Alcohol, exercise, and medical care (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 glycemia in diabetes mellitus
Glycemic control 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
Nutritional considerations in 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
●National Institute of Diabetes & Digestive & Kidney Diseases
●American Diabetes Association (ADA)
●The Endocrine Society
●Hormone Health Network
(www.hormone.org, available in English and Spanish)
The following reference books are a good source of information regarding diabetes and diet and carbohydrate counting.
●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