Lactation intensity and postpartum maternal glucose tolerance and insulin resistance

OBJECTIVEdTo examine the association between breastfeeding intensity in relation to maternal blood glucose and insulin and glucose intolerance based on the postpartum 2-h 75-g oral glucose tolerance test (OGTT) results at 6-9 weeks after a pregnancy with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODSdWe selected 522 participants enrolled into the Study of Women, Infant Feeding, and Type 2 Diabetes (SWIFT), a prospective observational cohort study of Kaiser Permanente Northern California members diagnosed with GDM using the 3-h 100-g OGTT by the Carpenter and Coustan criteria. Women were classified as normal, prediabetes, or diabetes according to American Diabetes Association criteria based on the postpartum 2-h 75-g OGTT results. RESULTSdCompared with exclusive or mostly formula feeding (.17 oz formula per 24 h), exclusive breastfeeding and mostly breastfeeding (#6 oz formula per 24 h) groups, respectively, had lower adjusted mean (95% CI) group differences in fasting plasma glucose (mg/dL) of 24.3 (27.4 to 21.3) and 25.0 (28.5 to 21.4), in fasting insulin (mU/mL) of 26.3 (210.1 to 22.4) and 27.5 (211.9 to 23.0), and in 2-h insulin of 221.4 (241.0 to 21.7) and 236.5 (259.3 to 213.7) (all P , 0.05). Exclusive or mostly breastfeeding groups had lower prevalence of diabetes or prediabetes (P = 0.02). CONCLUSIONSdHigher intensity of lactation was associated with improved fasting glucose and lower insulin levels at 6-9 weeks' postpartum. Lactation may have favorable effects on glucose metabolism and insulin sensitivity that may reduce diabetes risk after GDM pregnancy. 35:50-56, 2012 Diabetes Car