Gestational diabetes using diverse diagnostic criteria, risk factors including dietary intakes, pregnancy outcomes and postpartum glycemic status: a nested case-control study in Ghana
Authors: Agbozo Faith , Abubakari Abdulai , Zotor Francis , Jahn Albrecht 
Published: March 2019

Background

Gestational diabetes mellitus (GDM) has risen considerably in recent years. Studies from Africa have investigated the risk factors but reported prevalence is often based on one diagnostic test/cut-off while short-term outcomes have scarcely been explored. This study estimated the prevalence of GDM using diverse diagnostic cut-offs. Associated maternal risk factors, birth outcomes and extent of attainment of euglycemia at 12 weeks postpartum were also assessed.

Methods and Findings

This study was an unmatched case-control nested in a prospective cohort involving 807 pregnant women recruited consecutively from five state-owned hospitals serving rural and peri-urban communities in Ghana. Dietary and obstetric risks were assessed retrospectively while physiologic measurements were repeated throughout pregnancy. Case definition was fasting venous plasma glucose (FPG) ≥5.6 mmol/l and/or single-step 75-g 2-hour oral glucose tolerance test (OGTT) ≥8.5 mmol/l measured between 20-34 gestational weeks for singleton, non-diabetic pregnant women (n=446). Participants whose random blood glucose was ≥11.1 mmol/l and glycated hemoglobin ≥6.5% were excluded. Pregnancy outcomes of 403 women were traced at delivery while 100 could be followed-up at 12 weeks postpartum. Adjusted odds ratio (aOR) for GDM was tested through unconditional logistic regression and Mantel-Haenszel statistic and the association of GDM on pregnancy outcomes was estimated by multiple logistic regression.

Prevalence per 2-h OGTT ≥8.5 mmol/l was 9.0% (n=39, 95% confidence interval [CI]; 6.3-11.6) and prevalence per FPG ≥5.6 mmol/l was 10.8% (n=49, 95% CI; 8.1-13.9); 15.9% met the case definition. Independent risk factors included excess intake of high glycemic index foods (aOR:2.91 95% CI]:1.05-8.06), obesity (aOR:2.13 CI:1.12-4.03), previous cesarean delivery (aOR:4.01 CI:1.08-14.76) and antenatal care in a primary facility (aOR:4.951 CI:1.87-3.76). A unit rise in blood glucose significantly increased maternal blood loss and birthweight. Adjusting for covariates, adverse birth outcomes were perineal tear (Aor:2.91 CI:1.08-5.57) and birth asphyxia (aOR:3.24 CI:1.01-10.44). Cesarean section (aOR:1.9 CI:0.97-3.68), large for gestational age (aOR:2.7 CI:0.86-5.05) and newborn resuscitation (aOR:2.91 CI 0.94-9.01) were significant at 10%. At 12 weeks postpartum, 30% of the GDM cases were unable to achieve euglycemia. Different estimates could be obtained if other diagnostic criteria were used.

Conclusions

Findings show an increasing prevalence of GDM in peri-urban and rural settings highlighting the need to strengthen primary facilities to test and refer cases for management. Diet and adiposity are key risk factors necessitating lifestyle modification interventions focusing on nutrition education and weight control. GDM-exposed newborn need close monitoring as birth asphyxia which is a key outcome is likely to compromise neonatal survival. Postpartum follow-up of cases is crucial to avert transition of GDM into active diabetes.