Diet (nutrition) plays an important role in the management/treatment of diabetes, as well as for preventing and/or delaying the development of type-2 diabetes. Dietary approach can be used alone (in case of the beginning of type-2 diabetes and in mild hyperglycemia cases) or in combination with oral hypoglycemic drugs or insulin. Key to successful management of diabetes (especially type-2 diabetes) in a patient depends to a great extent in making the diabetes patient understand and follow a good dietary principle. The management of diabetes becomes simpler and easier for the treating physician as well as for the diabetes patient, if the patient understands and follows the dietary principles taught to him/her by the doctor or certified nutritionist/dietician.

Sometimes success or failure of management of diabetes may depend on the knowledge of the diabetes patient about the dietary principles in diabetes. The major aims of dietary management of diabetes are:

• To maintain blood sugar level within normal limit.
• To bring down body weight to as close to normal as possible and also to maintain it there.
• To prevent, delay and minimize the long term complications of diabetes, which are the major problems of diabetes.
• To maintain optimal nutrition.

The ADA (American Diabetes Association) advises MNT (medical nutrition therapy) for diabetes patients. MNT is optimal coordination of caloric intake with other aspects of diabetes therapy (insulin, oral hypoglycemic agents, exercise, weight loss etc.). American Diabetes Association recommends three types of MNT for diabetes, although one type of MNT may overlap with other type and vice versa.

• For primary prevention
• For secondary prevention and
• For tertiary prevention.

Medical Nutrition Therapy (MNT) for Primary Prevention of Diabetes:

MTN for primary prevention is directed at preventing or delaying as long as possible, development of type-2 diabetes in high risk individuals, such as obese and individuals with pre-diabetes state by reducing body weight to within normal. To get optimum benefits of MNT, the obese individuals may be tried with bariatric surgery and/or pharmacological approach for weight reduction.

MNT for Secondary Prevention of Diabetes:

The MNT for secondary prevention is directed at preventing and/or delaying diabetes-related complications (long term as well as short term complications) in diabetes patients by improving glycemic control.

MNT for Tertiary Prevention of Diabetes:

The MNT for tertiary prevention of diabetes is directed at managing the diabetes-related complications (especially long term complications such as cardiovascular disease, neuropathy, nephropathy, retinopathy etc.) in diabetic individuals e.g. in individuals with diabetes and chronic kidney disease (nephropathy), protein intake should be limited to 0.8 gram/kg of body weight per day, as compared to approximately 1 gram/kg/day for normal individuals.

MNT in diabetes patients with cardiovascular disease should incorporate the same dietary principles used in non-diabetic patients with cardiovascular disease. A balanced diet with fruits, vegetables, fiber-containing foods, and low-fat milk as advised for general population is advised for diabetics too. MNT should be individualized to meet the individual goals in the management of diabetes.

Historically nutrition education for diabetes patients imposes restrictive and complicated regimens on diabetes patient. But present (current) practice have greatly changed {e.g. MNT now includes foods with sucrose, which were restricted previously and aim to modify other risk factors such as hyperlipidemia (high blood lipids like cholesterol) and hypertension rather than focusing exclusively on weight loss in individuals with type-2 diabetes}, although many diabetes patients and diabetes care providers still regard the diabetic diet as monolithic and static.

Foods with high “glycemic index” tend to increase postpriandal (after food intake) blood glucose and foods with low “glycemic index” tend to lower postpriandal blood glucose and give better glycemic control, hence advised to be consumed liberally by diabetes patients. At present there is no scientific evidence which indicate supplementation of the diet with vitamins, antioxidants (vitamin C and E), or micronutrients (e.g. chromium) is required in patients with diabetes.

The aim of MNT in type-1 diabetes is to balance calorie intake with energy output with appropriate insulin adjustment. Self monitoring of blood glucose should be used to define the optimal insulin requirement, in individual diabetes patient. At present American Diabetes Association recommends to use carbohydrate counting systems (the amount of carbohydrate content of a meal or snack) to estimate the nutrient content of a meal or snack (although this may not be practicable in many situations) and determines the bolus insulin dose for a meal or snack.

The goal of MNT in type-2 diabetes is slightly different from type-1 diabetes as they have greatly increased prevalence of cardiovascular risk factors such as hypertension, dyslipidemia, obesity and cardiovascular disease. The prevalence of obesity is very high among patients of type-2 diabetes and MNT should encourage to reduce body weight and give due importance to weight loss. Low calorie diet and weight loss of 5-7% may result in great reduction in blood glucose level among type-2 diabetes patients and MNT should concentrate on long-term weight loss, (although long-term weight loss is uncommon among type-2 diabetes as many studies have shown). MNT for type-2 diabetes should emphasize on modest caloric reduction, reduced fat intake, increased physical activity, and control of hyperlipidemia and hypertension. Intake of soluble dietary fibers improves glycemic control and weight loss and exercise improve insulin resistance in type-2 diabetes.

MNT (for both type-1 and type-2 diabetes) should be flexible enough to allow for exercise, and the insulin regimen must allow for deviations in caloric intake.

Nutritional Recommendations for Adults with Diabetes:

Carbohydrates:

• Contrary to common belief, low carbohydrate diets are not recommended.
• Carbohydrate should constitute 45–65% of total caloric intake. Carbohydrate with low glycemic index should be consumed more and carbohydrates with high glycemic index should be avoided.
• Sucrose-containing foods may be consumed but dose of insulin should be adjusted accordingly.

Fats:

• Fats should constitute 20–35% of total caloric intake, with saturated fats constituting less than 7% of calorie intake.
• Dietary cholesterol should be less than 200 mgs/day.
• Consume fish at least twice a week for omega-3 polyunsaturated fatty acids.
• Consume minimal Trans fat.

Proteins:

• Avoid high protein diet.
• Protein should constitute 10-35% of total calorie intake. Proteins should be of high quality (contain all or most of the Essential Amino Acids).

Other Nutrients:

• Non-nutrient sweeteners (zero calorie sweeteners) may be used.
• Fiber-containing foods may reduce postprandial glucose, as they have low glycemic index.