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

Abstract

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/m² 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.