What is the recommended diet for a medically stable adult with type 2 diabetes mellitus to achieve optimal glycaemic control, maintain a healthy weight, and reduce cardiovascular risk?

Dietary Management of Type 2 Diabetes Mellitus

Core Dietary Recommendation

For adults with type 2 diabetes, prioritize a diet emphasizing nutrient-dense carbohydrates from vegetables, fruits, legumes, whole grains, and dairy products, with moderate calorie restriction (if overweight) to achieve ≥5% weight loss, while completely eliminating sugar-sweetened beverages and minimizing added sugars. 1

Weight Management Strategy

• Achieve weight loss of ≥5% through reduced calorie intake combined with lifestyle modification, which provides clinical benefits including improved glycemia, blood pressure, and lipid profiles, especially early in the disease process. 1

• Structured programs emphasizing reduced fat intake (<30% of daily energy), reduced total energy intake, regular physical activity, and ongoing participant contact produce sustainable long-term weight loss of 5-7% of starting weight. 1, 2

• Even modest weight loss improves insulin resistance and glycemic control; weight maintenance is preferable to weight gain if weight loss cannot be achieved. 1

Macronutrient Distribution

There is no single ideal percentage of calories from carbohydrate, protein, and fat—macronutrient distribution should be based on current eating patterns, preferences, and metabolic goals. 1

Carbohydrates (Primary Focus)

• Emphasize carbohydrate intake from vegetables, fruits, legumes, whole grains, and dairy products—specifically those higher in fiber and lower in glycemic load—over other carbohydrate sources, especially those containing added fats, sugars, or sodium. 1, 2

• The total amount of carbohydrate consumed and available insulin are the most important factors influencing glycemic response after eating. 1, 2

• Completely eliminate sugar-sweetened beverages (including fruit juices) to control glycemia, weight, and reduce cardiovascular disease and fatty liver risk. 1, 2

• Minimize consumption of foods with added sugar that displace healthier, more nutrient-dense food choices. 1

• Substituting low-glycemic load foods for higher-glycemic load foods may modestly improve glycemic control. 1

• Consume at least 14 g fiber per 1,000 kcal consumed, as recommended for the general population. 1

Dietary Fat (Quality Over Quantity)

• Adopt a Mediterranean-style eating pattern rich in monounsaturated and polyunsaturated fats as an effective alternative to a low-fat, high-carbohydrate diet—this improves glucose metabolism and lowers cardiovascular disease risk. 1, 2

• Total dietary fat should be moderated (25-35% of total calories) and consist mainly of monounsaturated or polyunsaturated fat. 1

• Limit saturated fats to <7% of energy intake and dietary cholesterol to <200 mg/day. 1

• Keep trans-unsaturated fatty acid intake to <1% of energy intake. 1

• Consume fatty fish rich in EPA and DHA at least twice weekly, plus nuts and seeds rich in ALA, to prevent cardiovascular disease. 1, 2

• Do not routinely use omega-3 dietary supplements—evidence does not support benefit for cardiovascular event prevention. 1

Protein

• Protein intake of 15-20% of total energy is appropriate for most patients with type 2 diabetes. 2

• In type 2 diabetes, ingested protein increases insulin response without increasing plasma glucose concentrations. 1, 3

• Avoid carbohydrate sources high in protein when treating or preventing hypoglycemia because protein triggers insulin response that may worsen low blood sugar. 1, 3, 2

• For patients without diabetic kidney disease, there is no specific ideal protein amount for optimizing glycemic control—goals should be individualized. 1

Acceptable Eating Patterns

Multiple eating patterns are acceptable for type 2 diabetes management, including: 1, 2

• Mediterranean diet (most consistently demonstrated metabolic and cardiovascular benefits with improved glycemic control) 1, 4, 5
• Low-carbohydrate diets (HbA1c reduction of 0.1-0.5%) 4
• Plant-based diets (HbA1c reduction of 0.2-0.4%) 4
• Low-glycemic index diets (HbA1c reduction of 0.2-0.5%) 4

Micronutrients and Supplements

• Do not routinely supplement with vitamins, minerals (including chromium and vitamin D), herbs, or spices (such as cinnamon or aloe vera) in patients without underlying deficiencies—there is no clear evidence of benefit for glycemic control. 1, 2

• Avoid routine supplementation with antioxidants such as vitamins E and C and carotene due to insufficient evidence of efficacy and long-term safety concerns. 1, 2

Sodium Restriction

• Limit sodium consumption to <2,300 mg/day, as recommended for the general population. 1, 2

• For individuals with both diabetes and hypertension, further individualized reduction in sodium intake may be indicated. 1

Alcohol Consumption

• If consuming alcohol, limit to one drink daily for women and two drinks daily for men, always consumed with food. 1, 2

• Alcohol consumption increases risk for hypoglycemia, especially when taking insulin or insulin secretagogues—education about recognition and management of delayed hypoglycemia is warranted. 1

Implementation Strategy

• All patients should receive individualized medical nutrition therapy from a registered dietitian to achieve treatment goals—this results in cost savings and improved outcomes including A1C reduction. 1

• For patients with limited health literacy, numeracy, or those prone to hypoglycemia, a simple approach emphasizing portion control and healthy food choices may be considered. 1

• Intensive lifestyle interventions with ongoing support (counseling about nutrition therapy, physical activity, and behavior change) are recommended to achieve and maintain weight loss. 1

Common Pitfalls to Avoid

• Do not use high-protein carbohydrate sources to treat hypoglycemia—the insulin response from protein can worsen low blood sugar. 1, 3

• Avoid focusing exclusively on weight loss at the expense of glycemic control and cardiovascular risk factor management. 1

• Do not recommend extremely low-fat diets high in carbohydrates as the default approach—Mediterranean-style diets with healthy fats are equally or more effective. 1

• Recognize that sucrose does not increase glycemia more than isocaloric amounts of starch, but minimize consumption to avoid displacing nutrient-dense foods. 1, 2