Hyperglycemia in pregnancy: A sensitivity analysis study of two recommended screening tests in Tanzania

Abstract

Screening for hyperglycaemia in pregnancy (HIP) is an entry point to a healthy pregnancy and childbirth for both the woman and child, and offers a window of opportunity for the prevention of cardio-metabolic complications over the life-course of the woman and newborn. In Tanzania, two different screening algorithms to identify women with HIP are recommended, with no clear understanding of which performs better. We aimed to determine the prevalence of hyperglycemia in pregnancy (HIP) among antenatal care (ANC) attendees and the accuracy of HIP screening tests. A cross-sectional study design involving 970 women attending ANC clinic was done in two district hospitals (Mbagala Rangi Tatu and Kisarawe) of Tanzania between June and October 2024. Socio-demographic, obstetric characteristics, and anthropometric parameters were obtained from study participants. A checklist screening test (CST) for gestational diabetes mellitus (GDM), defined by the Tanzanian standard treatment guideline, was used. We tested for glycosuria and two-hour 75-gram oral glucose tolerance test (OGTT) on every study participant. We conducted descriptive statistics and sensitivity analysis to determine the prevalence of HIP and assess the screening performance of CST and glycosuria test against OGTT using World Health Organization 2013 diagnostic criteria for GDM. The prevalence of HIP was 10% (7.9% GDM and 2.1% diabetes in pregnancy). Glycosuria test missed all women with GDM and could identify only 20% with diabetes in pregnancy. The CST had a sensitivity and specificity of 72.2% (62.1-80.8, 95%CI) and 32.4% (29.3-35.6, 95%CI), respectively, while the glycosuria test had 4.1% (1.1-10.2, 95%CI) and 97.1% (95.8-98.1, 95%CI). The area under the receiver operator characteristic curve for both the CST 0.523 (0.48-0.57,95%CI) and glycosuria test 0.506 (0.49-0.53,95%CI) was low, indicating their poor discriminatory performance for HIP. One in every ten women had HIP. The CST is a better first-step screening test than the glycosuria test based on sensitivity.

Fig 1. Description of recruitment of study participants and study procedures.

The results of the glycosuria test and the blood glucose test were documented in the study request form and the ANC record. A member of the research team also communicated the test results to the woman and the ANC clinic staff.

Fig 2. Study flowchart for inclusion of study participants for analysis.

Out of the 970 women included in the final analysis sample, 68.7% (666 women) were recruited at Mbagala Rangi Tatu Hospital (Table 3). Just half (52.2%) of the study participants were in the 20–29-years age group. A total of 40.2% had attained secondary school-level education and the majority (91.6%) were either married or living with a partner. About two-thirds (56.4%) had a BMI of ≥25 kg/m² and 4.1% were HIV-positive.

Fig 3. Receiver observer characteristics curve comparing checklist screening test and glycosuria tests for Hyperglycemia in pregnancy.