THE DIFFERENTIAL-EFFECTS OF BODY-FAT DISTRIBUTION ON INSULIN AND GLUCOSE-METABOLISM DURING PREGNANCY

OBJECTIVE: Our purpose was to investigate whether maternal obesity, or more specifically body fat distribution, is associated with alteratio ns in carbohydrate metabolism during pregnancy. STUDY DESIGN: A longit udal study of oral glucose tolerance tests, insulin, C peptide, and gl ucagon levels during each trimester and post partum was undertaken in nine lean and 14 obese women. Obese women were divided into lower body obese (n = 6, waist/hip ratio < 0.9) and upper body obese (n = 8, wai st/hip ratio greater than or equal to 0.9). RESULTS: Fasting blood glu cose levels declined with advancing gestation only in lean subjects. U pper body obese women demonstrated maximal glucose response and insuli n area under the curve by the second trimester, whereas lean and lower body obese women did not until the third trimester. Insulin areas wer e significantly elevated in upper body obese compared with lower body obese women (second trimester, p < 0.01; third trimester, p < 0.03; po et partum p < 0.05). In contrast, C peptide levels were similar in obe se subgroups and were significantly elevated only when compared with t hose of lean women. C peptide/insulin molar ratios were lower in upper body obese women during the second trimester (4.3 +/- 0.8) and third trimester (4.2 +/- 0.7) compared with lean (6.5 +/- 1.3, 6.7 +/- 0.5) and lower body obese women (7.9 +/- 1.4, 6.5 +/- 1.4) (p < 0.01). A si gnificant relationship between waist/hip ratio and glucose level (r = 0.70, p < 0.004) and insulin areas (r = 0.76, p < 0.001) was present i n late pregnancy in obese subjects. CONCLUSIONS: Relative hyperinsulin emia and earlier maximal glucose response in upper body obese women su ggests that body fat distribution may explain the metabolic heterogene ity present in obese women during pregnancy. Body fat topography may s erve as a potential marker for the early development of carbohydrate i ntolerance during pregnancy.