Laurie Barclay, MD


July 2, 2003 — A low-glycemic-index (GI) Mexican diet reduces weight and improves glycemic control in obese type 2 diabetic Mexicans, according to the results of a randomized study published in the July issue of Diabetes Care.

"We have not found long-term studies showing the effect of low-GI diets containing Mexican-style foods on either Mexicans or Mexican Americans with diabetes," write Arturo Jimenez-Cruz, MD, PhD, from Universidad Autónoma de Baja California, Mexico, and colleagues. "The typical Mexican diet includes beans (legumes) and corn tortillas (traditionally made), which are foods with a low GI. However, in Mexico and in the U.S., current dietary guidelines for people with diabetes focus on lowering dietary fat and increasing carbohydrate intake but do not mention the GI."

This crossover-design study comparing flexible diets with high or low GI consisted of two 6-week periods with a 6-week washout period between treatments. Of 36 enrolled subjects with type 2 diabetes and body mass index (BMI) greater than 25 kg/m2, 14 subjects completed the study with eligible dietary records.

During the low-GI diet, glycemic load and GI were lower, and subjects consumed significantly fewer high-GI carbohydrates, such as white-wheat bread, white long-grain rice, potatoes, high-GI fruits, and carrots. During the high-GI diet, dietary fiber was lower, and subjects consumed fewer low-GI carbohydrates, such as pinto beans, whole-meal wheat bread, and low-GI fruits.

However, there were no differences during the two study periods in the amount of carbohydrates consumed, such as corn tortillas and dairy products. At the end of the study periods, A1c improved on the low-GI diet compared with the high-GI diet (P < .008).

"Despite the worldwide controversy of the advantages and disadvantages of using the low-GI diet criteria for the nutrition education in diabetes, this study provides evidence that more flexible Mexican-style instructions, with an emphasis on the use of low-GI foods, decreased BMI and improved the metabolic control in individuals with type 2 diabetes," the authors write. "Although this diet helped to increase the adherence to the diet, it also promotes Mexican-style dishes, such as 'frijoles and tortillas,' increasing satiety as well as reducing body weight and improving metabolic control. Dietary recommendations for the treatment of Mexicans with type 2 diabetes may need to be reconsidered."

Omnilife-Conacyt supported this study.

Diabetes Care. 2003;26:1967-1970


http://www.medscape.com/viewarticle/458203