Glycemic Index and Insulinemic Index of 3 Types of Tortilla in Mexican Adults

Objective. To evaluate the effect of the intake of two types of whole corn tortilla, and one traditional tortilla on Glycemic Index (GI) and Insulinemic Index (InIn) in adults with diabetes, or overweight or clinically healthy.

Material and methods. A randomised crossover, single-blinded study design will be undertake in adults 20-69 years. The study will use 3-arm: 1) Adults with diabetes (n=27); b) adults with overweight (n=27); and c) clinically healthy adults (n=27). During a week run-in period subjects will record their normal habitual diet for 7d. Individuals will be request to maintain their normal exercise, and sleeping patterns before reporting for testing.

Upon arrival to the laboratory, participants will be weight and body composition was determined. Overnight fasted (8-12 hours) participants reported to the Research Center of Mexican National Institute of Public Health on 4 occasions separated by at least one week. The glycemic and insulinemic index will be measure for each group of participants given in random order the following foods with a 1-week washout period in between: 1) a whole corn tortilla (white "criollo" corn= 5.3% fiber), 2) a whole corn tortilla (white "hybrid" corn= 7.9%), 3) a traditional corn tortilla (3.9% fiber), and 4) white bread (reference food containing 2.2% of fiber). The rations shall be 50g of carbohydrates available each (approximately equivalent to 4 tortillas or 4 breads, respectively).

Blood samples were collected again at 0, 15, 30, 45, 60, 90 and 120 minutes after completion of the test meal. Insulin and glucose will be measure by electrochemiluminescence and the hexokinase method, respectively. The GI values were determined according to Food and Agriculture Organization of the United Nations (FAO). The area under the curve will be calculated as the incremental area under the blood glucose response curve for each test in each individual. This study and the sampling of the volunteers were performed following approval of the ethics Committee of Mexican National Public Health Institute

Inclusion criteria

• One group (n=27) with a diagnosis of type 2 diabetes documented by fasting blood glucose.
• One group (n=27) with overweight by Body Mass Index (BMI) >=25 kg/m2
• One group (n=27) with healthy adults without non communicable chronic diseases

Exclusion criteria

• Alterations associated with digestion and bariatric surgery