A Mediterranean and a high-carbohydrate diet improve glucose metabolism inhealthy young persons

Aims/hypothesis. Insulin resistance usually precedes the diagnosis of Type II (non-insulin-dependent) diabetes mellitus. However, in most patients, th e clinical expression of the disease could be prevented by dietary and life style changes. We investigated the effects of a diet enriched in monounsatu rated fatty acids (Mediterranean diet) and a low fat, high-carbohydrate die t on in vivo and in vitro glucose metabolism in 59 young subjects (30 men a nd 29 women). Methods. We carried out an intervention dietary study with a saturated fat phase and two randomized-crossover dietary periods: a high-carbohydrate die t and a Mediterranean diet for 28 days each. We analysed the plasma lipopro teins fractions, free fatty acids, insulin sensitivity and glucose uptake i n isolated monocytes at the end of the three dietary periods. Results. In comparison to the saturated fat diet, the CHO and Mediterranean diets induced a decrease of LDL-cholesterol (p < 0.001) and HDL-cholestero l (p < 0.001). Steady-state plasma glucose decreased (p = 0.023) and basal and insulin-stimulated 2-deoxiglucose uptake in peripheral monocytes increa sed in both diets (CHO and Mediterranean), (p = 0.007) indicating an improv ement in insulin sensitivity. Fasting free fatty acids plasma values were c orrelated positively with steady state plasma glucose (r = 0.45; p < 0.0001 ). In addition, there was an inverse correlation between the mean glucose o f the steady state plasma glucose period and logarithmic values of basal (r = -0.34; p = 0.003) and insulin stimulated glucose uptake in monocytes (r = -0.32; p = 0.006). Conclusion/interpretation. Isocaloric substitution of carbohydrates and mon ounsaturated fatty acids for saturated fatty acids improved insulin sensiti vity in vivo and in vitro, with an increase in glucose disposal. Both diets are an adequate alternatives for improving glucose metabolism in healthy y oung men and women.