Glucose metabolism in pregnancy at high altitude

OBJECTIVE - To assess insulin sensitivity and beta -cell function associate d with lower material fasting plasma glucose levels at high altitude compar ed with sea level. RESEARCH DESIGN AND METHODS - We studied 215 pregnant women at 8-42 weeks o f gestation in Peru. The women were recruited from Cerro de Pasco, which is situated 4.370 m (14,340 feet) above sea level, and Lima, which is at sea level. We also examined 53 nonpregnant control subjects (22 in Cerro de Pas co and 31 in Lima). Fasting plasma glucose, insulin, C-peptide, and proinsu lin concentrations were measured in samples obtained from the antecubital v ein between 8:00 A.M. and 10:00 A.M. after an overnight period of lasting f or 10-14 h. Insulin resistance and beta -cell function were calculated usin g homeostasis model assessment. RESULTS - Fasting C-peptide levels and beta -cell function were similar, fa sting concentrations of insulin and proinsulin were lo il er, and insulin s ensitivity was higher at high altitude compared with sea level. CONCLUSIONS - Maternal Fasting plasma glucose that is lower at high altitud e than at sea level in the presence of similar insulin secretion is associa ted with higher peripheral insulin sensitivity. This may partly explain the lower birth weights at high altitudes.