An energy-restricted, high-monounsaturated fat (MUFA) diet is as effective as a high-carbohydrate (CHO), low-fat diet in persons with type 2 diabetes, according to the results of a study.
Largely because of increasing rates of obesity, the prevalence of type 2 diabetes in the United States is rising steadily. Although nutrition is a vital aspect of diabetes management, few controlled clinical trials have determined optimal dietary recommendations for people with type 2 diabetes.
To reduce plasma lipid levels, reduced intake of saturated fat and cholesterol are typically recommended. However, it is unclear whether saturated fat should be replaced with carbohydrate or with monounsaturated fat, and some evidence suggests that diets high in MUFA may be more beneficial than high-CHO diets.
"Medical nutrition therapy is an integral component of diabetes management, but there have been few controlled clinical trials on which to base nutritional recommendations for people with diabetes," write Bonnie J. Brehm, PhD, from the University of Cincinnati in Cincinnati, Ohio, and colleagues. "Decreasing the intake of saturated fat and cholesterol with the goal of decreasing plasma lipid levels has been an almost universal prescription for those with, or at risk for, diabetes. There has been controversy about whether to replace saturated fat with carbohydrate or monounsaturated fat since evidence suggests diets high in monounsaturated fat (MUFA) may be healthier than low-fat, high-carbohydrate diets."
The goal of this study was to compare the efficacy of a high-MUFA diet and a high-CHO diet on controlling body weight and glucose levels in men and women with type 2 diabetes. The study sample consisted of 124 overweight or obese participants with type 2 diabetes. Mean age was 56.5 ± 0.8 years, body mass index was 35.9 ± 0.3 kg/m2, and hemoglobin A1c (HbA1c) level was 7.3% ± 0.1%. Participants were randomly assigned to follow a high-MUFA diet or a high-CHO diet for 1 year, and anthropometric and metabolic parameters were evaluated at baseline and after 4, 8, and 12 months of dieting.
Both groups had similar characteristics at baseline. Retention rate of following the diet for 1 year was 77% overall (69% for the high-MUFA group, 84% for the high-CHO group; P = .06). Analysis of food records revealed similar energy intake in both groups but significantly different MUFA intake.
Weight loss during 1 year was not significantly different between groups (–4.0 ± 0.8 kg vs –3.8 ± 0.6 kg), nor was improvement in body fat, waist circumference, diastolic blood pressure, high-density lipoprotein cholesterol levels, HbA1c levels, and fasting glucose and insulin levels.
Eighteen months after completion of the 52-week diet, 36 participants underwent follow-up evaluation. Weight loss and HbA1c levels were maintained during follow-up in these participants.
"In persons with type 2 diabetes, high-MUFA diets are an alternative to conventional lower-fat, high-CHO diets with comparable beneficial effects on body weight, body composition, cardiovascular risk factors, and glycemic control," the study authors write. "These results, the first to test the effectiveness of a high-MUFA diet over a lengthy period in free-living diabetic persons in the United States, indicate that either dietary approach can provide clinical benefits in persons with type 2 diabetes."
Limitations of this study include failure of the high-MUFA group and the high-CHO group to reach their target goals for monounsaturated fat and carbohydrate intake, respectively; limitations of self-reporting as a measure of energy intake; lack of information about the participants’ drug usage during the study; and lack of sophisticated measures of glucose metabolism.
"Practitioners can offer ongoing counseling for a variety of diets higher in either carbohydrate or monounsaturated fat, while controlled in calories," the study authors conclude. "By forgoing the ‘one size fits all’ philosophy and providing diet options, practitioners may enhance patients’ dietary compliance and ultimately reduce disease risk."
- In men and women with type 2 diabetes, high-MUFA and high-CHO diets were equally effective in compliance and weight loss at 1 year. Retention rate was good in both groups. Both groups lost approximately 4% of initial body weight during 1 year, and improvements in body fat and waist circumference were similar in both groups.
- In men and women with type 2 diabetes, high-MUFA and high-CHO diets were equally effective in glycemic control and metabolic parameters at 1 year. Both groups had similar improvements in fasting glucose, insulin, HbA1c, diastolic blood pressure, and high-density lipoprotein cholesterol levels. The positive effects of both diets were clinically meaningful in that they would be expected to reduce cardiovascular risk.
Diabetes Care. Published online October 28, 2008.
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