EFFECTS OF A MONOUNSATURATED FATTY ACID-ENRICHED HYPOCALORIC DIET ON CARDIOVASCULAR RISK-FACTORS IN OBESE PATIENTS WITH TYPE-2 DIABETES

OBJECTIVE - To determine whether the lipoprotein response to weight lo ss in obese patients with type 2 diabetes can be improved by modifying the macronutrient composition of the commonly prescribed low-fat, hig h-carbohydrate (CHO) hypocaloric diet. RESEARCH DESIGN AND METHODS - N ine obese patients with type 2 diabetes were treated with a monounsatu rated fatty acid (MUFA)-enriched weight-reducing formula diet and comp ared with eight obese patients with type 2 diabetes treated with a low -fat, high-CHO weight-reducing formula diet. Weight loss ensued for 6 weeks, followed by 4 weeks of refeeding using isocaloric formulas enri ched with MUFA or CHO, respectively Fasting blood samples were obtaine d to measure plasma lipoproteins and LDL susceptibility to oxidation ( measured as lag time: time required to induce in vitro formation of co njugated dienes). RESULTS - At baseline, there were no differences bet ween the groups in plasma lipids, lipoproteins, or LDL susceptibility to oxidation. Weight loss was similar between the groups. Dieting resu lted in decreases in total plasma cholesterol, LDL, HDL, triglycerides , and apolipoproteins A and B (P < 0.05), but the MUFA group manifeste d a greater decrease in total cholesterol, triglycerides, and apolipop rotein B and a smaller decrease in HDL and apolipoprotein A than the C HO group (P < 0.05). Improvements in these parameters were sustained d uring refeeding. After dieting, lag time was prolonged in the MUFA gro up (208 +/- 10 min) compared with the CHO group (146 +/- 11 min; P < 0 .05). Lag time was prolonged further during refeeding in the MUFA grou p (221 +/- 13 min, P = 0.10), while the CHO group remained unchanged ( 152 +/- 9 min, P < 0.05). Lag time correlated strongly with the oleic acid content of LDL after dieting and refeeding (r = 0.74 and r = 0.93 , respectively, both P < 0.001). CONCLUSIONS - Macronutrient content i s an important determinant of the lipoprotein response to weight loss in obese patients with type 2 diabetes. MUFA-enriched hypocaloric diet s potentiate the beneficial effects of weight loss to ameliorate cardi ovascular risk factors in obese patients with type 2 diabetes.