Effect of High Monounsaturated Fat Diet on Glycemic Control and Cardiovascular Risk Factors in Type 2 Diabetes

The incidence of type 2 diabetes has increased steadily over the last three decades. Although medical nutrition therapy is an integral component of diabetes management, nutrition recommendations for diabetes have often been based on clinical experience and expert consensus, rather than on carefully controlled clinical trials. The expert consensus on medical nutrition therapy is that carbohydrate and monounsaturated fat together should provide approximately 60-70% of total energy intake. This recommendation accommodates parties on both sides of a debate over what constitutes the optimal macronutrient composition of a diet for type 2 diabetic patients. On one side are proponents of high carbohydrate, low fat diets who contend that this regimen promotes the lowering of total- and LDL-cholesterol and is less calorically dense than diets containing a higher percentage of fat. On the other side are advocates of high monounsaturated fat, Mediterranean-type diets who cite data from short-term studies indicating that this approach decreases postprandial levels of plasma glucose, insulin, and triglycerides, and increases HDL-cholesterol more than isocaloric high carbohydrate diets. However, there is concern about the potential for high fat diets to increase energy intake and weight gain among free-living subjects. To make definitive, scientifically-based diet recommendations, it is essential that controlled long-term trials be conducted to demonstrate the health effects of specific percentages of monounsaturated fats and carbohydrates in the diets of persons with type 2 diabetes.

Inclusion criteria

• BMI of 27-40 kg/m2
• 30-75 years of age
• Stable body weight for the preceding 6 months
• Diagnosis of type 2 diabetes for at least 6 months prior to enrollment
• HbA1c of 6.5 to 9.0
• Treatment by diet or oral agents only

Exclusion criteria

• Pregnancy or lactation
• Active cardiac, pulmonary, renal, liver, or gastrointestinal disease
• Untreated thyroid disease or hypertension
• Hypertriglyceridemia with levels of TG > 500 mg/dl
• Use of insulin
• Use of specific medications that may alter lipid or glucose metabolism (other than the statins)
• Use of medications that commonly cause significant alterations in body weight (e.g., corticosteroids).