A flexible, low-glycemic index mexican-style diet in overweight and obese subjects with type 2 diabetes improves metabolic parameters during a 6-week treatment period.

OBJECTIVE The aim of this study was to compare the effects of a flexible lower- and higher-glycemic index (GI) Mexican-style diet on biochemical data and BMI during a 6-week treatment period. RESEARCH DESIGN AND METHODS This study was a randomized, crossover design of two 6-week periods with a 6-week washout period between treatments. Subjects with type 2 diabetes (n = 36) with a BMI >25 kg/m(2) were selected. Fourteen subjects completed the study with eligible dietary records. Dietary instruction was provided on flexible diets with both a high and low GI. Fasting venous blood samples were taken at the start and finish of each dietary period, and biochemical data were analyzed. Multi- and univariate one-factor repeated-measures ANOVA were used to compare biochemical data. RESULTS Glycemic load and GI were lower during the low-GI diet, and dietary fiber was lower during the high-GI diet. The participants in the low-GI period consumed significantly fewer carbohydrates, such as white-wheat bread, white long-grain rice, potatoes, high-GI fruits, and carrots, and more carbohydrates, such as pinto beans, whole-meal wheat bread, and low-GI fruits than did participants in the high-GI period. There were no differences in the amount of carbohydrates consumed, such as corn tortillas and dairy products. At the end of the study periods, A1c was improved on the low- compared with the high-GI diet (P < 0.008). CONCLUSIONS We conclude that a low-GI diet, containing Mexican-style foods, may help to improve the metabolic control in type 2 obese diabetic subjects during a 6-week period.