The effect of lactation on glucose and lipid metabolism in women with recent gestational diabetes.

To investigate the effect of lactation in the puerperium on glucose and lipid metabolism in women with recent gestational diabetes. In women with recent gestational diabetes, we examined the effect of 4-12 weeks of lactation on glucose tolerance (2-hour oral glucose tolerance test) and on fasting serum lipids (total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, and triglycerides). Of 809 women tested in the puerperium, 404 elected to breast-feed and 405 did not lactate. The mean (+/- standard deviation) maternal age (31.6 +/- 5.9 versus 30.5 +/- 6.3 years), body mass index (28.8 +/- 5.1 versus 28.8 +/- 4.5 kg/m2), and parity (3.0 +/- 1.6 versus 2.8 + 1.7) were not different between the lactating and nonlactating groups, respectively. Glucose metabolism improved in the lactating group, indicated by a significantly lower total area under the glucose tolerance curve (17.0 +/- 4.2 versus 17.9 +/- 5.0 g.minute/dL; P = .01), mean fasting serum glucose (93 +/- 13 versus 98 +/- 17 mg/dL; P = .0001), and mean 2-hour glucose level (124 +/- 41 versus 134 +/- 49 mg/dL; P < .01). These differences were significant after adjusting for maternal age, body mass index (BMI), and the use of insulin in pregnancy. Nursing had no effect on total cholesterol, LDL cholesterol, or triglyceride levels. However, the mean serum HDL cholesterol was elevated in the lactating group after adjusting for maternal age, BMI, and pregnancy insulin use compared with the nonlactating group (48 +/- 11 versus 44 +/- 10 mg/dL; P < .01). Lactation, even for a short duration, has a beneficial effect on glucose and lipid metabolism in women with gestational diabetes. Breast-feeding may offer a practical, low-cost intervention that helps reduce or delay the risk of subsequent diabetes in women with prior gestational diabetes.