Oral glucose tolerance during the menstrual cycle in normal women and women with alleged premenstrual "hypoglycemic" attacks: effects of naloxone.

To resolve existing controversies about the impact of the menstrual cycle on oral glucose tolerance, we examined the glucose, insulin, and glucagon responses to an oral glucose challenge at different phases of the menstrual cycle in five normal women (NW) and six women with premenstrual syndrome and alleged premenstrual hypoglycemic attacks (PMHA). Responses to oral glucose did not differ significantly between follicular and luteal phase studies in either group, nor were significant differences found between the responses of NW and women reporting PMHA. In parallel studies, the possible glucoregulatory effects of endogenous opiates were assessed. Concomitant infusion of naloxone altered neither the basal concentrations of glucose, insulin, and glucagon nor the responses of these measures to the glucose challenge. We conclude that NW and women with premenstrual syndrome and alleged PMHA have no menstrual cycle-related changes in glucose, insulin, or glucagon responses to an oral glucose load. The fact that four of six PMHA subjects had symptoms typical of hypoglycemia at glucose nadirs above 50 mg/dl suggests that an explanation other than hypoglycemia must be sought for such symptomatic episodes. Endogenous opiate peptides appear to exert no glucoregulatory effects at naloxone-sensitive receptor sites.