Glucose tolerance during moderate prolonged exercise in women with oral contraceptives as compared to non-users

Background. The purpose of this study was to assess glucose tolerance during exercise in women on oral contraceptives. Methods. To this end, we investigated the effects of glucose ingestion on glucose and hormonal responses in 7 women on oral contraceptives (OC(+); 21.3 +/-1.3 yrs) and 7 normally menstruating (OC(-); 22.6 +/-1.3 yrs) during an ergocycle test (30 min, 60% VO2max). Venous blood samples were withdrawn at 0, 3, 5, 10, 15 and 30 min exercise and at the 30(th) min postexercise. Glucose was ingested per os (0.5 g(.)kg(-1) b.w) between the 2(nd) and the 3(rd) min of the exercise. Results. Under resting condition, plasma glucose and catecholamine concentrations were similar in both groups whereas plasma GH and insulin levels were greater in OC(+) (p<0.05). Glucose/insulin ratio (G/I), used as an indicator of insulin resistance, suggested a reduced insulin sensitivity at rest in the OC(+) (p<0.05). No significant differences were observed between OC(+) and OC(-) in plasma glucose, insulin, and catecholamine concentrations during exercise. Plasma GH values were greater in OC(+) from the 15(th) min of the exercise and during the recovery period (p<0.01). Conclusions. This study indicated that oral glucose ingestion at the onset of prolonged submaximal exercise induced similar glucose tolerance in women taking or not oral contraceptives.