Effect of the Dietary Approaches to Stop Hypertension (DASH) diet on the development of preeclampsia and metabolic outcomes in pregnant women with pre-existing diabetes mellitus: a randomised, controlled, single-blind trial

Preeclampsia (PE) affects up to five times more women with pre-existing diabetes mellitus (PDM) than women without it. The present study aimed to identify the effect of the DASH diet on PE incidence ( primary outcome) and blood pressure, glycated haemoglobin (GH), serum lipids, glutathione peroxidase (GP), C-reactive protein (CRP - secondary outcomes) in pregnant with PDM. This randomised, controlled, single-blind trial studied sixty-eight pregnant women with PDM throughout prenatal care until delivery (18 weeks) at a public maternity hospital, Brazil. The standard diet group (SDG) received a diet containing 45-65 % carbohydrates, 15-20 % protein and 25-30 % lipids. The DASH diet group (DDG) received the adapted DASH diet with a similar macronutrient distribution, but with a higher concentration of fibres, unsaturated fats, calcium, magnesium and potassium as well as lower saturated fat. Student's t, Mann-Whitney U and the Chi-square tests were used to compare outcomes. PE incidence was 22.9 % in the SDG and 12.1 % in the DDG (P = 0.25). GP levels significantly increased in the DDG (intra-group analysis; mean difference = 1588 [CI 181, 2994], P = 0.03) and tended to be different from the variation in the SDG (mean difference = -29.5 [CI -1305; 1.365]; v. DDG: 1588 [CI 181; 2994], P = 0.09). GH levels decreased significantly and similarly between groups (SDG: -0.61 [CI -0.26, -0.96], P = 0.00) v. DDG: -1.1 [CI -0.57, -1.62], P = 0.00). There was no evidence of a difference in PE incidence at the end of the intervention between the two diets. The DASH diet seems to favour PE-related biochemical markers.