Effect of macronutrient intake during the second trimester on glucose metabolism later in pregnancy

Background: Dietary intake is known to influence glucose metabolism, but there is little consensus on the optimal distribution of macronutrient intakes during pregnancy to prevent gestational diabetes (GDM). Objective: We aimed to investigate whether macronutrient intake distribution during the second trimester of pregnancy was associated with glucose metabolism later in pregnancy. Design: Women with singleton pregnancies and without preexisting type 1 or type 2 diabetes were included. Participants underwent a 3-h oral-glucose-tolerance test at 30 wk (95% CI: 25, 33 wk) gestation and were asked to recall their second-trimester dietary intake by using a validated food-frequency questionnaire. Results: Of the 205 participants, 47 (22.9%) had a diagnosis of GDM. A higher intake of saturated fat (beta +/- SEE: 0.059 +/- 0.021; P = 0.005) and trans fat (0.381 +/- 0.145; P = 0.009) as a percentage of energy and of added sugar (0.017 +/- 0.007; P = 0.02) and a lower intake of vegetable and fruit fiber (20.026 +/- 0.012; P = 0.03) were individually associated with increased fasting glucose after multiple adjustment. In participants with a family history of type 2 diabetes, a higher vegetable and fruit fiber intake was associated with reduced insulin resistance (20.100 +/- 0.029; P = 0.0008) and increased insulin sensitivity (0.029 +/- 0.012; P = 0.01), after similar adjustment. An increased risk (OR per 1-SD change) of GDM was associated with lower carbohydrate (0.60; 95% CI: 0.40, 0.90) and higher total fat (1.61; 95% CI: 1.06, 2.44) intakes as a percentage of energy, after similar adjustment. Conclusions: Macronutrient intake during the second trimester of pregnancy was associated with a risk of abnormal glucose metabolism later in pregnancy. This finding supports the need for continued work to determine optimal prenatal nutritional strategies to prevent GDM. This trial is registered at clinicaltrials.gov as NCT01405547. Am J Clin Nutr 2011;94:1232-40.