Insulin Sensitivity and Insulin Secretion Estimated by Homeostatic Model Assessment (HOMA) in Gestational Diabetes Mellitus

Background: Progressive insulin resistance (IR) is an important pathophysiologic mechanism of gestational diabetes mellitus (GDM). Homeostatic model assessment (HOMA) is commonly used as a parameter of the severity of insulin resistance. Aims: To determine indices of insulin resistance (IR) and β-cell function in gestational diabetes mellitus (GDM). Methods: This cross sectional study was conducted from March 2017 to September 2018 at Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. The study was performed with 41 GDM and equal number of pregnant women with normal glucose tolerance (NGT) diagnosed on basis of WHO criterion-2013 during 24 - 40 weeks of gestation. Serum glucose was measured by glucose oxidase method and fasting serum insulin was measured by chemiluminescent immunoassay. Equations of homeostatic model assessment (HOMA) were used to calculate insulin indices like-insulin resistance (HOMA-IR), β-cell function (HOMA-B) and insulin sensitivity (HOMA-%S). Data were analyzed and compared by statistical tests. Results: A total of eighty-two (82) subjects [41 women with GDM (age: 28.29 ± 3.79 years, BMI: 27.16 ± 4.13 kg/m2) and 41 women with NGT (age: 26.22 ± 5.13 years, BMI: 25.27 ± 3.01 kg/m2)] were included in this study. It was observed that GDM women were significantly older (p = 0.041) and had significantly higher BMI (p = 0.020) than pregnant women with NGT. The GDM group had significantly higher IR as indicated by higher fasting insulin value [GDM vs. NGT; 10.19 (7.71 - 13.34) vs. 6.88 (5.88 - 8.47) μIU/ml, median (IQR); p = 0.001] and HOMA-IR [GDM vs. NGT; 2.31 (1.73 - 3.15) vs. 1.42 (1.15 - 1.76), median (IQR); p β-cell secretory capacity [GDM vs. NGT; HOMA-B: 112.63 (83.52 - 143.93) vs. 128.60 (108.77 - 157.58), median (IQR); p = 0.04] and low insulin sensitivity [GDM vs. NGT; HOMA-%S: 43.29 (31.77 - 57.98) vs. 70.42 (56.86 - 86.59), median (IQR); p < 0.001]. Conclusions: GDM is associated with both insulin resistance and inadequate insulin secretion.