Nutrition in Patients With Diabetes

Updated: Dec 14, 2015
  • Author: Fazia Mir, MD; Chief Editor: George T Griffing, MD  more...
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Diabetes is a chronic illness that requires a holistic approach in terms of care to prevent both acute and long-term complications. Nutritional management for diabetic patients has been evolving for 100 years as the pathophysiological basis of the complications incurred from diabetes becomes more explicit.

Medical nutrition therapy is extremely important for diabetic patients and prediabetic patients so that adequate glycemic control can be achieved. One-on-one consultations with a registered dietician well-versed in diabetic nutrition are most preferable, as has been shown in studies performed in Pakistan [1] and Hungary, [2] which proved the utility of a dietician in improving dietary adherence. Nutrition counseling should be sensitive to the personal needs of the patient and how much effort the patient is willing to put in to making the change to eating appropriately.

Medical nutrition therapy for diabetics can be divided into (1) dietary interventions and (2) physical activity. Lifestyle and dietary modifications form the cornerstone of therapy in type 2 diabetic patients (insulin resistance). In type 1 diabetic patients, who have an insulin deficiency, a balance between insulin and nutrition needs to be obtained for optimal glycemic control. [3]


Dietary Interventions

Nutrition for diabetic patients can be further divided into prevention and continual management of glycemic control. Prevention is more for individuals at risk for developing diabetes and for type 2 diabetic patients than for patients who have already developed complications, in order to prevent further progression.

The goals of nutrition in prevention are as follows:

  • Primary prevention – Identification of the population at high risk (body mass index [BMI] >25), obesity, or prediabetic state and implementation of diet and lifestyle changes

  • Secondary prevention - Utilization of nutrition as therapeutic modality to achieve euglycemia in diabetic patients

  • Tertiary prevention - Nutrition as tool to manage the macrovascular and microvascular complications of diabetes and to delay morbidity and mortality

Food groups include macronutrients and micronutrients. There is no optimal diet mix of macronutrients that can be prescribed to the entire diabetic population. Dietary needs must be individualized. Reduction in fat (saturated fats, trans -fats, cholesterol) intake in diabetic patients is aimed at decreasing cardiovascular disease risk by reducing plasma cholesterol and low-density lipoprotein (LDL) cholesterol levels. [4]

Low-carbohydrate and low-fat diets used to achieve initial weight loss are effective for the short term (approximately 1 y) and need monitoring with a lipid profile and renal function tests. Low-carbohydrate diets (20-120 g/d) carry the additional benefit of a favorable lipid profile as compared with low-fat diets. Low-carbohydrate diets have also been noted to decrease fasting plasma glucose values by about 21-28 mg/dL. [5, 6]

The so-called Mediterranean diet may be an option. One study in which subjects (N=322) were randomized to 1 of 3 diets (Mediterranean, restricted-calorie; low-fat, restricted-calorie; low-carbohydrate, non–restricted-calorie) found that at 2-year follow-up, the 36 diabetic subjects assigned to the Mediterranean diet had more favorable fasting plasma glucose and insulin levels compared with those assigned to the low-fat diet. [7]

For patients who are on insulin therapy or oral hypoglycemics, being on a restrictive diet requires adjustment of dosage to prevent hypoglycemia.

Carbohydrate choices in diabetes are as follows:

  • Carbohydrates necessary for energy, some vitamins, fiber, and dietary palatability and as a major regulator of postprandial glucose levels

  • Recommended daily allowance for carbohydrates is 130 g/d [8]

  • Type of carbohydrates (ie, starch, amylose, amylopectin) consumed reflects on postprandial glucose values

  • Consumption of low–glycemic index foods can result in a drop of 0.4% in hemoglobin A1C compared with high–glycemic index foods [9] ; limitations to this diet choice include bloating and a restrictive diet

  • Nonnutritive sweeteners have fewer calories compared with regular sucrose used in table sugar but have not been shown to reduce glycemia, accelerate weight loss, or cause weight gain [10]

Dietary fat recommendations in diabetes are as follows:

  • Total dietary cholesterol consumption of less than 200 mg/d

  • Saturated fat intake consumption of a maximum of only 7% of one’s daily intake

  • Servings of nonfried fish recommended weekly as a form of omega-3 fatty acids, which have been postulated to reduce adverse cardiovascular disease outcomes [11]

  • Plant sterols intake to block intestinal absorption of cholesterol and lower total plasma LDL cholesterol percentage, if intake is around 2 g/d [12]

Protein recommendations in diabetes are that a good quality, high-protein diet is recommended. This measure can aid in achieving weight loss and blood glucose level control. [5]

In addition to the macronutrients, micronutrients are an important component of a balanced diet. Uncontrolled diabetic patients are usually micronutrient deficient because of poor dietary choices. Physicians should encourage meeting daily needs from a healthy, balanced diet rather than from supplementation with multivitamins. [13] If this cannot be achieved, then a daily multivitamin is acceptable. Zinc, copper, and chromium have been studied but do not play any role in achieving tight glycemic control. [14]

Much interest has been sparked in the role of antioxidants and diabetes, as diabetes has been noted to be a state of oxidative stress. Flaxseed has been shown in experiments to decrease inflammatory markers in type 2 diabetic patients, but there are no specific and reliable recommendations. [15] Vitamin E in combination with other antioxidants has the tendency to do more harm than good if taken over prolonged periods. [13] Patients should always be asked about their use of herbal supplements for treatment of their type 2 diabetes, as herbal supplements can interact with other medications and produce unexpected adverse effects. To date, evidence of herbal supplements aiding diabetes management is insufficient. [16]

Adults with diabetes who choose to indulge in alcohol should be cautioned about the risk of nocturnal hypoglycemia if it is consumed without food at night. [17] It has been recommended that men should limit their intake to 2 drinks per day, while for women 1 drink per day is suggested. One alcohol beverage is defined as a 12-oz serving of beer, a 5-oz serving of wine, and a 1.5-oz serving of distilled spirits. Complete abstinence from alcohol should be advised to people who have severe peripheral neuropathy and hypertriglyceridemia.


Physical Activity

Physical activity of 150 minutes per week is especially recommended for type 2 diabetic patients, as it causes moderate weight loss and increased insulin sensitivity. If vigorous activity is being performed, then the time duration is 125 minutes per week, with no more than 2 consecutive days without training. [18]

The National Heart, Blood and Lung Institute, [19] using the National Health and Nutrition Examination Survey (NHANES) data, defines persons being overweight as having a BMI of 25-29.9 kg/m2 and as being obese as having a BMI greater than 30 kg/m2.

For type 2 diabetic patients with a BMI greater than 35 kg/m2, greater benefit has been noted if they undergo bariatric surgery compared with continual medical therapy with regard to glucose control and weight loss. [20] Weight loss medications help in the initial 5-10% of weight loss and are recommended for patients with established diabetes who have a BMI of greater than 27 kg/m2. [21] Studies have shown that a high BMI with an increased waist circumference (indicator of visceral fat) is a predictor of the development of type 2 diabetes and cardiovascular disease. In both short- and long-term studies evaluating weight loss and its resultant effect on a drop in hemoglobin A1C, however, results have not been consistent.

Yoga has been suggested as an alternative for severe diabetic patients who may be unable to participate in strenuous activity. Malhotra et al undertook a 20-patient study in Delhi, India and concluded that yoga has a beneficial effect on glucose control, as well as promoting weight loss. [22]

A current trial, Look AHEAD (Action for HEAlth in Diabetes), [23] has been designed to evaluate outcomes of long-term weight loss on glycemia and the development of cardiovascular disease. For type 1 diabetic patients with macrovascular or microvascular complications, an individualized exercise regimen is warranted as strenuous exercise can result in complications. If patients have active proliferative diabetic retinopathy, they should be advised to refrain from strenuous exercise or Valsalva maneuvers, as these can precipitate vitreous hemorrhage. Patients with microalbuminuria (>20 mg/min albumin excretion) or frank proteinuria (>200 mg/min protein excretion) should not engage in high-intensity physical activity.

In type 1 diabetic patients, the risk for developing hypoglycemia exists during, immediately after, or several hours after of engaging in physical activity, which mandates adjustment in the therapeutic regimen patients may be following. Supplemental carbohydrates should be taken if finger-stick glucose values are less than 100 mg/dL prior to initiating exercise.

Key precautions for exercise programs in diabetes are as follows:

  • Evaluation of the patient prior to embarking on an exercise regimen, with a thorough physical examination and careful medical tests, with documentation of grade of retinopathy, nephropathy, and neuropathy (both peripheral and autonomic)

  • Baseline resting ECG to check for any ST and T segment abnormalities; additional radionuclide stress testing may be warranted

  • Doppler ultrasound and ankle brachial index if evidence of peripheral arterial disease is present

  • Should a patient with sensitive feet undertake exercise, ulceration and fractures may result; weight-bearing exercises should be limited; swimming is the ideal exercise in this case

  • A warm-up and cool-down session of 5-10 minutes must always be undertaken

  • Use of silica gel or air midsoles, in addition to polyester or blend (cotton-polyester) socks, to prevent blisters and maintain circulation

  • Footwear should be appropriate at all times

  • Patient examination of the feet prior to, as well as after, undertaking physical exercise

  • Diabetic bracelet should be worn and steps should be taken to ensure its visibility

  • An average of 17 oz of fluids should be consumed at least 2 hours prior to the start of exercise in order to maintain adequate hydration



Managing diabetes requires a multidisciplinary approach, and nutrition and physical exercise are 2 significant facets to help reduce the global burden of the diabetes epidemic. To ensure successful outcomes, physicians, patients, and dietitians need to work together. Studies have shown one-on-one consultations with a qualified registered dietician improve patient adherence to prescribed diabetic diets. [1, 2]

The cornerstones of therapy for type 2 diabetic patients are diet and lifestyle modifications. For type 1 diabetic patients, the goal of optimal glycemic control can be achieved with a balance between insulin and nutrition needs.