Serum Leptin Correlates with Obesity But Does Not Differ Between Gestational Diabetes and Normal Glucose Tolerance during 24-28 Weeks of Gestation.

Leptin is an adipocytokine secreted by adipocytes which positively correlates with obesity. It is considered as a potential mediator for precipitating Gestational diabetes mellitus (GDM) which is more evident during 24-28 weeks of gestation. This study was conducted to see serum leptin level during 24-28 weeks of gestation in GDM at the Department of Endocrinology, BSMMU, Bangladesh from March 2019 to August 2020. Pregnant women (N=108) were challenged with 75gm oral glucose (OGTT) at 24-28 weeks of gestation and divided into GDM [n=45, age: 27.80±3.98 years, mean±SD; BMI: 27.88 (24.46-30.43) kg/m², median Interquartile range (IQR)] and normal glucose tolerance [NGT; n=62, age: 26.19±5.30 years, mean±SD; BMI: 25.80 (23.65-28.42) kg/m², median (IQR)] on basis of WHO-2013 diagnostic criteria. Fasting serum leptin and glucose were measured by ELISA and glucose oxidase method respectively. No statistically significant difference was found between GDM and NGT for leptin [26.05(16.92-50.55) vs. 23.50(14.95-38.30) median (IQR), p=0.360]. It was also not different statistically between GDM and NGT either for age groups (p=NS for all) or for Asian categories of BMI subgroups (p=NS for all). However, it was higher in subjects with BMI ≥23kg/m² than that with BMI ≤23kg/m² for both GDM [16.65 (6.39, 35.75) vs. 28.35 (19.60, 51.10) median (IQR), p=0.114] and NGT [14.65(9.19, 19.60) vs. 26.00 (17.30, 43.40) median (IQR), p=0.002]. It was also statistically similar in the GDM subgroups divided by Asian BMI cut-off (p=NS). BMI correlated with leptin in NGT (r=0.495, p<0.001) but not in GDM (r=0.177, p=0.251) and regression analysis revealed BMI (kg/m²) as predictor for high leptin (p=0.008). ROC curve analysis for leptin showed AUC for GDM was 0.553 (p=0.360) suggesting it as a poor predictor. It is concluded that fasting leptin in 24-28 weeks of gestation better relates with BMI but does not differ between GDM and NGT anddoes not seem to be a good predictor for GDM. Further study is required to make a comment on its prediction over GDM.