Circadian variation of serum glucose,C-peptide immunoreactivity and free insulin in normal and insulin-treated diabetic pregnant subjects

Summary To examine differences among pregnant diabetic and nondiabetic subjects, serum glucose, and immunoreactivity of C-peptide, free and total insulin were measured at hourly intervals during a 24-h third trimester metabolic ward evaluation. Six normals, three mild, and four juvenile-onset type diabetics were studied. Diets were identical for all subjects. Mild diabetics differed from juvenile diabetics by having significant residual pancreatic B-cell function, as measured by C-peptide immunoreactivity. Short and intermediate acting insulins given once or twice daily to diabetics maintained serum glucose levels within the normal range throughout the 24 h. Despite wide variation in serum total insulin levels, peripheral free insulin concentrations in well-controlled diabetics fell within a relatively narrow range that was higher than in controls. Infants of the diabetic subjects were comparable to the offspring of the control women.This study was supported through funds provided by the Bureau of Medicine and Surgery, Navy Department, for CIP 4-48-364, and USPHS grants AM-13941 and AM-17046 (University of Chicago Diabetes Endocrinology Center). The group in Chicago also was supported by a gift from the Bertha and Henry Brownstein Foundation.These data were presented in part before the Endocrine Society, New York, New York, 18 June 1975.The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Navy Department or the naval service at large.On leave of absence from Kyoto University Medical School, Kyoto, Japan.