WOMEN AT ALTITUDE - CHANGES IN CARBOHYDRATE-METABOLISM AT 4,300-M ELEVATION AND ACROSS THE MENSTRUAL-CYCLE

We hypothesized that, in women, the blood glucose response to a meal ( BGR) would be lower after exposure to 4,300 m compared with sea level (SL) and that BGR would be reduced in the presence of estrogen plus pr ogesterone (E+P) relative to estrogen alone (E). Sixteen women were st udied in both the E and E+P conditions at SL and in either the E or EP condition at 4,300 m. On day 9 in each condition, blood was sampled before, and every 30 min for 2 h after, the subjects ate a high-carboh ydrate meal. At 4,300 m, BGR peaked at a lower value (5.73 +/- 0.94 mM ) than at SL (6.44 +/- 1.45 mM) and returned to baseline more slowly ( P < 0.05). Plasma insulin values were the same but C peptide was sligh tly higher at 4,300 m (P < 0.05). At SL, BGR returned to baseline more slowly in E+P condition (5.13 +/- 0.89 and 5.21 +/- 0.91 mM at 60 and 90 min, respectively) relative to E condition (4.51 +/- 0.52 and 4.69 +/- 0.88 mM, respectively) (P < 0.05). Insulin and C peptide were not different between E and E+P conditions. The data indicate that BGR is lower in women at high altitude compared with the SL, possibly due to greater suppression of hepatic glucose production or stimulation of p eripheral glucose uptake by insulin. BGR was lower in E condition rela tive to E+P condition at SL and possibly at 4,300 m, but the relative concentrations of ovarian hormones do not appear to alter the magnitud e of the change in BGR when women are exposed to high altitude.