Gender characteristics of the circadian rhythm of carbohydrate metabolism

Abstract

Aim of the study was to explore the gender characteristics of the circadian rhythm of carbohydrate metabolism in men and women with normal body weight. Materials and methods. 15 men and 22 women aged 18 to 56 entered the study and underwent clinical, antropometric, biochemical and hormonal examination. Standard oral glucose tolerance test (OGTT) was also performed in the morning and in the evening. Results and discussion. During OGTT performed in morning time there were no differences in mean baseline blood glucose levels between men and women. However higher glucose levels at 120th minute of the test in men demonstrated relative deceleration of glucose utilization in the morning in this group. Higher glucose levels at 120th minute during OGTT in the evening both in men and women comparing with baseline results, and also higher glucose levels at 120th minute of the test in the evening comparing with morning test, indicate decreased glucose tolerance. Insulin to glucose ratio values in men at all timepoints during OGTT were comparable in the morning and in the evening, but in women they were found to be higher in the evening than in the morning. Conclusion. In evening time both in men and women with normal body weight reduced rate of glucose utilization in peripheral tissues reflects circadian rhythm of carbohydrate metabolism. Gender differences of the circadian rhythm of carbohydrate metabolism consist in reduced glucose tolerance in the morning in men comparing to women that is associated with higher waist to hip circumference ratio in men which in turn is related to cumulation of visceral adipose tissue. Presumably greater amount of visceral adipose tissue in men determines more pronounced manifestations of insulin resistance in the morning.