Diabetes is a disease characterized by an inability to store and use glucose. Glucose is a simple sugar and is the main source of cellular energy in the body. There are different types of diabetes: type 1 diabetes, formerly referred to as juvenile-onset or insulin-dependent diabetes; type 2 diabetes, formerly referred to as adult-onset diabetes; gestational diabetes, which comes about during pregnancy; and pre-diabetes, in which blood sugar levels are higher than normal but are lower than those needed for a type 2 diabetes diagnosis. Pre-diabetes and type 2 diabetes are the most prevalent forms of the disease and are increasingly common in Westernized societies.

Diabetes should be managed with a combination of diet and regular exercise and, when necessary, medication. Each of these components plays a major role in a person’s overall health and well-being. 

Type 1 diabetes—People with type 1 diabetes must take insulin every day in order to process the food they eat and use it for energy. You will work closely with your doctor to determine the right doses and timing for your insulin. The most important things to remember are:

• eat at consistent times that match the timing of your insulin doses
• monitor your blood sugar levels
• adjust your insulin doses for the amount of food you eat and the amount of physical activity in which you engage

Type 2 diabetes—People with type 2 diabetes may not need to take insulin to manage their disease, but often will take other medication to help control their blood sugar. Your main dietary goals are:

• keeping blood sugar levels as stable as possible
• reducing or preventing high cholesterol and triglyceride levels
• achieving and maintaining normal blood pressure
• getting to a healthy body weight by reducing your daily calorie intake and exercising at least two and a half hours per week
• reducing chronic low-level inflammation to improve insulin activity and prevent diabetes complications

Gestational diabetes—Gestational diabetes increases the risk of other health problems during pregnancy as well as the mother's risk of developing type 2 diabetes after pregnancy. Pregnant women have the added responsibility of eating for two—what you eat and how well you control your blood sugar will impact the growth and development of your fetus. With this in mind, the most important goals for your diet are:

• eating nutritious foods that provide all of the essential nutrients for you and the child you are carrying
• eating enough calories to support adequate growth and development of your baby without causing excessive weight gain or hyperglycemia (high blood sugar)
• choosing complex carbohydrate sources that are high in fiber, and balancing carbohydrates with adequate amounts of proteins and fats
• pregnant women, including those with gestational diabetes mellitus (GDM), should consume a minimum of 175 grams of carbohydrates per day based on the Dietary Reference Intake (DRI) for pregnant women. However, complex carbohydrates should be chosen, and refined sugars should be minimized. Also, total carbohydrate intake should be less than 45% of energy to prevent hyperglycemia in women with GDM. 
• following the diet prescribed by your doctor or healthcare professional

Pre-diabetes—Although this is not true diabetes, having pre-diabetes puts you at high risk for developing type 2 diabetes. The dietary goals for people with pre-diabetes are similar to those for people with type 2 diabetes:

• achieving and maintaining normal blood pressure, cholesterol, and triglyceride levels
• getting to a healthy weight through cutting calories and exercising regularly
• eating a diet that reduces chronic low-level inflammation, thereby preventing the progression of diabetes as well as the health problems associated with diabetes

If adults with diabetes choose to drink alcohol, they should be advised to do so in moderation (one drink per day or less for adult women and two drinks per day or less for adult men). Some people, such as those with high blood pressure, should in many cases avoid alcohol. But always follow your doctor's advice about how much alcohol you may drink if you have pre-diabetes or any other type of diabetes.

More about this diet

Carbohydrates are the sugars and starches found naturally in grains and cereals, fruits and fruit juices, dairy products, legumes, and in small quantities in vegetables. In addition, carbohydrates such as sucrose (table sugar) and fructose (usually as high fructose corn syrup) are commonly added to many processed foods. Diabetes is a disease that makes the body unable to process carbohydrates due to problems with the hormone insulin. In people with type 1 diabetes, the problem is a lack of insulin due to autoimmune destruction of the pancreatic cells that makes insulin, but in people with type 2 diabetes, the problem is the body’s cells’ decreasing sensitivity to insulin. This reduced insulin sensitivity, also called insulin resistance, is widely believed to be caused by cellular damage resulting from chronic low-level inflammation throughout the body. Adding to the problem, insulin resistance increases inflammatory activity in the body and so is part of a self-perpetuating cycle.

Multiple meal planning approaches and eating patterns can be effective for achieving blood sugar control. The meal planning approach or eating pattern should be selected based on the individual's personal and cultural preferences. For example, for people who manage their diabetes with medications, one important strategy is to match the amount of carbohydrates they eat at each meal or snack with their prescribed insulin or other medications to prevent their blood sugar levels from dropping too low (hypoglycemia). This is known as carbohydrate counting. Carbohydrate counters don’t necessarily have to restrict the amounts of starches, legumes, and fruits they eat, but they do need to be consistent about how much and when they eat them. If your health care provider recommends carbohydrate counting, they will guide you in how to analyze labels on processed foods, make the best choices when you eat out, and prepare healthy foods at home.

Having type 2 diabetes puts you at higher risk of developing cardiovascular disease, kidney disease, non-alcoholic fatty liver disease, and obesity. Because of the relationship between diabetes and these conditions, improving your overall health with smart diet and exercise choices is very important. Eating lots of fruits and vegetables, plenty of fiber-rich foods like whole grains and beans, and mono- and polyunsaturated fats like those in nuts, seeds, and fish can help you keep your blood pressure, cholesterol levels, and triglyceride levels down, reduce your risk of other chronic health problems, and improve your general health.

Most people with diabetes take medications to help control their blood sugar levels. Whether you are taking insulin several times a day or an oral glucose-lowering medication such as metformin, be sure to carefully follow the instructions your prescribing physician provides. Consult with your physician before changing your medications or making big changes in your diet or exercise routine.

Like everyone else, people with all types of diabetes need to exercise regularly. Exercise improves insulin sensitivity, helps control weight, reduces risks of cardiovascular and other chronic diseases, and increases your sense of well-being. Everyone needs to make an exercise plan that works for them, and everyone’s plan will be different, but the general recommendation for people with diabetes is a minimum of 150 minutes (2.5 hours) of moderate intensity exercise per week. A consultation with a fitness expert may be helpful as you develop an exercise plan that works for your age, ability, interest, and schedule. Exercise increases the rate at which glucose is metabolized to produce energy, and hypoglycemia (low blood sugar) can occur during or after exercise in people taking blood sugar-lowering drugs. If you use medications to manage your diabetes, check with your prescribing doctor before adding or changing an exercise routine.

Having diabetes can be overwhelming, especially at first. Enlisting the help of nutritionists or dieticians, nurses, doctors, and other healthcare professionals can help build your confidence as you learn to live with diabetes and become adept at the self-care strategies that ensure your best possible long-term health.