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Gestational diabetes mellitus in Tanzania – public health perspectives Abstract Background: Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset or first recognition during pregnancy. Women with GDM are at increased risk for preeclampsia during pregnancy and for delivery complications. In most cases GDM ends after pregnancy, but it increases the risk for future type 2 diabetes, and cardiovascular diseases, to both the mother and the child. With the current increase in prevalence of overweight/obesity and type 2 diabetes in Tanzania and other Sub Saharan African countries, it is possible that GDM may exist and may be on the rise. Methods: A cross-sectional survey was done in 2011 through 2013 where 910 women in Tanzania (609 from urban, 301 from rural areas) were studied during their usual antenatal clinic visits. Weight, height, mid upper arm circumference (MUAC), blood pressure and haemoglobin levels were measured by a trained technician. Blood glucose was measured at fasting and at two hours after 75 g oral glucose tolerance test. Women were classified as having GDM using WHO 1999 criteria. Sociodemographic information was collected through face-to-face interviews using structured questionnaire or retrieved from the antenatal clinic card. Dietary intake data was collected using 24-hour recall interview and foods were categorised into groups based on dietary diversity. The international physical activity questionnaire (IPAQ) was used to assess activities in the past one week. Information on birth outcome was obtained from 466 urban mothers (response rate 77%) through telephone interviews. To estimate the burden of GDM in the region, we additionally conducted a systematic search of published literature on the prevalence and risk factors of GDM in Sub Saharan Africa. Out of the 22 reviewed studies, 15 studies graded as having low or moderate risk of bias were included in a meta-regression analysis. Finally, a review of literature regarding the health system and antenatal care was done and supported by a survey to assess antenatal care services in 24 health facilities that provide maternal and childcare services in Dar es Salaam region. Results: The prevalence of GDM was much higher among women residing in the urban (8.4%) compared to those in the rural areas (1.0%), which was much higher compared to 0% reported in the 1990s. Prevalence of GDM was higher for women who had a previous stillbirth, family history of type 2 diabetes and MUAC ≥28 cm, and lower for women with normal haemoglobin concentrations compared to those with anaemia. Likewise, the prevalence of hypertension disorders of pregnancy (HDP) was higher in urban (8.9%) compared to rural areas (5.3%). Risk factors for HDP in urban women were advanced maternal age, high MUAC, gestional age and being HIV positive, and in rural women age and gestational age. We reviewed 22 studies conducted in six out of the 47 Sub saharan African countries. Heterogeneity between the studies was high and it could not be significantly explained by study setting, population, diagnostic criteria, or the year the study was done. Nevertheless, a relatively higher prevalence was observed in studies done after the year 2000, when women at risk were selected and when more current diagnostic criteria were used. The prevalence was up to about 14.0% when women with at least one risk factor were studied. In Dar es Salaam women, despite a high prevalence of anemia and HIV, the prevalence of macrosomia was higher (5.9%) compared to the prevalence of low birth weight (3.6%). Presence of GDM (OR 3.46, 95% CI 1.01-11.85) and birth weight of the previous child (OR 2.42, 95% CI 1.17-4.99) were the main predictors of macrosomia and HDP (OR 3.75, 95% CI 1.11-12.68) was the main predictor of low birth weight. Although glucose testing in urine appeared to be universally done in the urban setting, the sensitivity of this test for detection of GDM is low. Therefore selective blood glucose testing should be implemented and HIV testing and counselling may be used as an entry point. Conclusions: The prevalence of GDM and HDP was higher in the urban compared to the rural areas in Tanzania, indicating an increasing in women who are at risk for delivery complications, poor pregnancy outcomes, type 2 diabetes and cardiovascular diseases in later life. The risk factors observed can be used to identify risk groups for screening and as target for prevention interventions. To inform policy makers and for better health care planning, further studies on the costs for blood glucose testing during the usual antenatal clinic visits and on the management of women with GDM are warranted. |
