Prevalence of gestational diabetes mellitus, insulin resistance and associated risk factors among pregnant women in a tertiary health setting in Calabar, Nigeria

Background: Gestational Diabetes Mellitus (GDM) is a common undiagnosed feature in many pregnant women in the tropics. Many of these undiagnosed women later progress to type 2 diabetes mellitus. This condition affects many pregnancies, and its prevalence is increasing worldwide. Understanding the pathophysiology and increasing the likelihood of identifying women at risk of GDM is vital to effective prevention and optimal treatment. Aims and Objectives: To assess the prevalence of GDM and insulin resistance in susceptible pregnant women with a view to identifying the risk factors associated with these conditions among women Attending Antenatal Care (ANC) clinic at the University of Calabar Teaching Hospital (UCTH), Calabar. Material and Methods: One hundred and eighty women pregnant women between 24–28 weeks of gestation attending ANC at UCTH Calabar were enrolled as participants in this study. Ethical approval and informed consent were taken from the women who participated in the study, and were administered oral glucose tolerance test after an overnight fast. Fasting samples for plasma insulin, triglyceride, and total cholesterol were collected as well. Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and beta-cell function (HOMA-β) were both derived from the fasting plasma glucose and insulin. A well-structured questionnaire containing general information on demographic characteristics, socioeconomic status, and obstetric and gynaecological characteristics was filled up for each participant. Statistical analyses were done to assess the prevalence and the associated risk factors. Results: A prevalence of 37.7% was observed for GDM. The majority of the women with GDM were > 25 years of age (79.4%), married (93.9%), educated (tertiary 66.7%, secondary 32.8%), employed (70.6%), and resided in the urban area (72.2%). Most were either overweight (38.3%) or obese (38.9%). Most of the women with GDM were primigravida (40%) and para 1 (37.3%), had previous caesarean section (52.8%), previous preterm delivery (95.4%), and previous stillbirth (45.8%). Based on risk factor assessment, ironically, 45.6% (majority) of women with GDM were of low risk, 29.5% of average risk, and 13.2% of high risk. The prevalence of insulin resistance among participants, as indicated by various biomarkers, was significant: Fasting Plasma Glucose (FPG) 30.6%, fasting plasma insulin 41.1%, triglycerides 11.1%, total cholesterol 51.1%, and insulin resistance index (HOMA-IR) 67.8%. FPG (p = 0.000) and HOMA-IR (p = 0.004) were found to be significantly associated with the development of GDM among the women. Conclusion: A high prevalence of GDM (37.7%) and insulin resistance was found among the antenatal population in UCTH Calabar. HOMA-IR and FPG were significantly related to the development of GDM. And several socio-demographic factors (based on jobs and careers) were linked to this association.