The Association Between Measures of Prepregnancy Insulin Resistance and Sensitivity with Subsequent Risk of Gestational Diabetes

Context: Little is known about the association between prepregnancy homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β-cell function (HOMA-β) levels and risk of gestational diabetes mellitus (GDM). Objective: To examine the association between prepregnancy levels of HOMA-IR and HOMA-β and risk of GDM and whether these associations vary by race and ethnicity. Research Design and Methods: We conducted a nested case-control study among women who had a serum sample from 1984 to 1996 used to measure glucose and insulin and a subsequent pregnancy from 1984 to 2009. GDM cases (n = 254) were matched with 2 randomly selected control subjects (n = 497) on serum collection date, age at collection, number of intervening pregnancies, and age at delivery. We used conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for GDM by HOMA-IR and HOMA- β, overall and stratified by race and ethnicity. Results: Increasing levels of HOMA-IR were associated with higher odds of GDM (adjusted OR for 1 SD increase: 1.31 [95% CI 1.12,1.54]) and tertile 3 compared to tertile 1 (3.04 [95% CI 1.81, 5.12]). Models stratified by race/ethnicity suggest this association was significant among Asian and non-Hispanic Black populations for tertile 3 (3.83 [95% CI 1.39, 10.57] and 2.18 [95% CI 1.03, 4.61], respectively). Among non-Hispanic Black individuals, a 1 SD increase in HOMA-IR also increased risk of GDM (OR: 1.59, 95% CI 1.17, 2.17). There was no significant association between HOMA-IR and GDM among non-Hispanic White or Hispanic individuals. There was no association between HOMA-β and GDM risk. Conclusion: Higher HOMA-IR levels before pregnancy were associated with an elevated risk of GDM.