Are Changes in Whole-Body Insulin Sensitivity during Pregnancy Related to Changes in Ectopic Fat Stores?

Abstract

Background: Our study is one of the first to assess relationships between changes in ectopic lipid stores [intrahepatic (IHL), intramyocellular (IMCL), and extramyocellular (EMCL)] from early to late pregnancy and changes in whole-body insulin sensitivity. Methods: We evaluated 31 women without diabetes and enrollment BMI’s 18.5-38 kg/m2 in early (mean [min-max] 15.6 [12.9-17.3] weeks) and late (34.2 [32.3-37.3] weeks) gestation. Women with pregestational diabetes or multifetal pregnancies were excluded. Participants underwent insulin clamps to assess whole-body insulin sensitivity (M-value), 1H magnetic resonance spectroscopy to assess IHL, IMCL, and EMCL content, and BODPOD to assess % body fat, fat mass, and lean mass. Results: Women were primarily white (90%) with mean (min-max) age of 30.5 (19 -39) years. M-value declined 27% between early and late visits (p<.001) and IHL, IMCL, and EMCL increased (p<.05). M-value was not significantly correlated with any total or ectopic fat in late pregnancy. Changes in these body composition variables from early to late pregnancy were not significantly associated with changes in M-value. Conclusion: Whole-body insulin sensitivity declines from early to late pregnancy but was unrelated to changes in ectopic and total fat. Non-body composition factors appear to be the primary determinant of gestation-related insulin resistance.Table. Means, standard deviations, and Pearson’s correlation coefficients for insulin sensitivity (M-value), weight, and total and ectopic fat measures at late pregnancy and from early to late pregnancy.MeasureMean (SD) Late pregnancyCorrelation with M-valueMean (SD) change from early to late pregnancyCorrelation of change in measure with change in M-ValueM Value275.7 (69.8)--100.3 (112.6)*--Weight (kg)82.9 (12.3).3210.5 (3.3)-.01BMI (kg/m2)28.7 (3.8).153.6 (1.1)-.01Body fat (%)33.3 (6.4).18-0.8 (3.6).00Fat mass (kg)28.2 (8.7).253.0 (3.2).05Lean mass (kg)54.7 (5.9).297.5 (2.6)-.08IHL (% water peak)0.6 (0.3).120.1 (0.2)*-.18IMCL (% water peak)1.2 (0.6).010.3 (0.6)*-.02EMCL (% water peak)2.3 (1.4).290.5 (1.2)*-.06*p<.05 Disclosure K. Vesco: None. N.E. Marshall: None. W. Rooney: None. M.C. Leo: None. E. Baetscher: None. M. Francisco: None. J.Q. Purnell: Advisory Panel; Self; Novo Nordisk Inc..