Effects of a Plant-Based High-Carbohydrate/High-Fiber Diet Versus High–Monounsaturated Fat/Low-Carbohydrate Diet on Postprandial Lipids in Type 2 Diabetic Patients

Abstract

OBJECTIVE To search for a better dietary approach to treat postprandial lipid abnormalities and improve glucose control in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS According to a randomized crossover design, 18 type 2 diabetic patients (aged 59 ± 5 years; BMI 27 ± 3 kg/m²) (means ± SD) in satisfactory blood glucose control on diet or diet plus metformin followed a diet relatively rich in carbohydrates (52% total energy), rich in fiber (28g/1,000 kcal), and with a low glycemic index (58%) (high-carbohydrate/high-fiber diet) or a diet relatively low in carbohydrate (45%) and rich in monounsaturated fat (23%) (low-carbohydrate/high–monounsaturated fat diet) for 4 weeks. Thereafter, they shifted to the other diet for 4 more weeks. At the end of each period, plasma glucose, insulin, lipids, and lipoprotein fractions (separated by discontinuous density gradient ultracentrifugation) were determined on blood samples taken at fasting and over 6 h after a test meal having a similar composition as the corresponding diet.

RESULTS In addition to a significant decrease in postprandial plasma glucose, insulin responses, and glycemic variability, the high-carbohydrate/high-fiber diet also significantly improved the primary end point, since it reduced the postprandial incremental areas under the curve (IAUCs) of triglyceride-rich lipoproteins, in particular, chylomicrons (cholesterol IAUC: 0.05 ± 0.01 vs. 0.08 ± 0.02 mmol/l per 6 h; triglycerides IAUC: 0.71 ± 0.35 vs. 1.03 ± 0.58 mmol/l per 6 h, P < 0.05).

CONCLUSIONS A diet rich in carbohydrate and fiber, essentially based on legumes, vegetables, fruits, and whole cereals, may be particularly useful for treating diabetic patients because of its multiple effects on different cardiovascular risk factors, including postprandial lipids abnormalities.