The effect of low glycemic index foods taken at dinner on blood glucose and insulin levels in patients with type 2 diabetes

Introduction: Diabetes is one of the most common endocrine diseases. With regard to the importance of blood glucose regulation in prevention of diabetic complications, glycemic and insulinemic response determination of foods containing carbohydrates is greatly important. The purpose of the present study, therefore, was to determine the effect of low glycemic index foods taken at dinner on fasting blood glucose and subsequent breakfast glycemic and insulinemic responses in patients with type 2 diabetes. Materials and Methods: The study was a randomized, cross-over clinical trial in which 8 diabetic patients (4 male and 4 female), were randomly allocated to one of the following two diet regimens: 1) Dinner with high glycemic foods: Potato puree, egg white, "Lavash" bread, and oil. 2) Dinner with low glycemic foods: cooked lentils, "Sangak" bread, and oil. The following day, fasting venous blood samples were collected, then the two groups received standard breakfast which included toast bread, cheese, and tea. Venous blood samples were collected at 60, 120 and 180 minutes following breakfast. Serum glucose was measured by enzymatic methods (glucose oxidase) and serum insulin by ELISA. The washout period was 7 days and then the order of the study was reversed. The data were statistically analyzed by paired t- test. Results: Characteristics of the patients were as follows: age 60.25±10.3 years, duration of diabetes 11.5±3.5 years, body mass index 27.123 kg/m² and fasting blood glucose 159.3837.5 mg/dL. Fasting blood glucose differences with postprandial breakfast levels were significantly lower in low glycemic group than the high glycemic group at 120 (277.9± 67.2 vs. 226.7±54.8 mg/dL, p<0.03) and 180 minutes (229.5±75.3 vs. 159.8± 57.7 mg/dL, p<0.05). The post-breakfast IUAC (area under incremental curve) for glucose was lower after consumption of low glycemic foods (21187.5±6607.9 vs. 13605±1979.9 mg.min/dL, p<0.01). 3) Differences between serum insulin levels at zero, 60, 120 and 180 minutes after starting breakfast with the fasting level were similar in the two groups. The post-breakfast IUAC for insulin was similar in the two groups. Conclusion: It is concluded that the use of low glycemic foods at dinner can decrease fasting glucose and insulin levels, as well as glycemic and insulinemic responses after breakfast in patients with type 2 diabetes mellitus. This can possibly have a great role in regulating blood glucose in these patients.