Lactation and Progression to Type 2 Diabetes Mellitus After Gestational Diabetes Mellitus: A Prospective Cohort Study.

BACKGROUND: Lactation improves glucose metabolism, but its role in preventing type 2 diabetes mellitus (DM) after gestational diabetes mellitus (GDM) remains uncertain. OBJECTIVE: To evaluate lactation and the 2-year incidence of DM after GDM pregnancy. DESIGN: Prospective, observational cohort of women with recent GDM. (ClinicalTrials.gov: NCT01967030). SETTING: Integrated health care system. PARTICIPANTS: 1035 women diagnosed with GDM who delivered singletons at 35 weeks' gestation or later and enrolled in the Study of Women, Infant Feeding and Type 2 Diabetes After GDM Pregnancy from 2008 to 2011. MEASUREMENTS: Three in-person research examinations from 6 to 9 weeks after delivery (baseline) and annual follow-up for 2 years that included 2-hour, 75-g oral glucose tolerance testing; anthropometry; and interviews. Multivariable Weibull regression models evaluated independent associations of lactation measures with incident DM adjusted for potential confounders. RESULTS: Of 1010 women without diabetes at baseline, 959 (95%) were evaluated up to 2 years later; 113 (11.8%) developed incident DM. There were graded inverse associations for lactation intensity at baseline with incident DM and adjusted hazard ratios of 0.64, 0.54, and 0.46 for mostly formula or mixed/inconsistent, mostly lactation, and exclusive lactation versus exclusive formula feeding, respectively (P trend = 0.016). Time-dependent lactation duration showed graded inverse associations with incident DM and adjusted hazard ratios of 0.55, 0.50, and 0.43 for greater than 2 to 5 months, greater than 5 to 10 months, and greater than 10 months, respectively, versus 0 to 2 months (P trend = 0.007). Weight change slightly attenuated hazard ratios. LIMITATION: Randomized design is not feasible or desirable for clinical studies of lactation. CONCLUSION: Higher lactation intensity and longer duration were independently associated with lower 2-year incidences of DM after GDM pregnancy. Lactation may prevent DM after GDM delivery. PRIMARY FUNDING SOURCE: National Institute of Child Health and Human Development.

Lactation intensity and fasting plasma lipids, lipoproteins, non-esterified free fatty acids, leptin and adiponectin in postpartum women with recent gestational diabetes mellitus: the SWIFT cohort.

OBJECTIVES: Lactation may influence future progression to type 2 diabetes after gestational diabetes mellitus (GDM). However, biomarkers associated with progression to glucose intolerance have not been examined in relation to lactation intensity among postpartum women with previous GDM. This study investigates whether higher lactation intensity is related to more favorable blood lipids, lipoproteins and adipokines after GDM pregnancy independent of obesity, socio-demographics and insulin resistance. METHODS: The Study of Women, Infant Feeding, and Type 2 Diabetes (SWIFT) is a prospective cohort study that recruited 1035 women diagnosed with GDM by the 3-h 100g oral glucose tolerance tests (OGTTs) after delivery of a live birth in 2008-2011. Research staff conducted 2-h 75 g OGTTs, and assessed lactation intensity, anthropometry, lifestyle behaviors and socio-demographics at 6-9 weeks postpartum (baseline). We assayed fasting plasma lipids, lipoproteins, non-esterified free fatty acids, leptin and adiponectin from stored samples obtained at 6-9 weeks postpartum in 1007 of the SWIFT participants who were free of diabetes at baseline. Mean biomarker concentrations were compared among lactation intensity groups using multivariable linear regression models. RESULTS: Increasing lactation intensity showed graded monotonic associations with fully adjusted mean biomarkers: 5%-8% higher high-density lipoprotein cholesterol (HDL-cholesterol), 20%-28% lower fasting triglycerides, 15%-21% lower leptin (all trend P-values < 0.01), and with 6% lower adiponectin, but only after adjustment for insulin resistance (trend P-value = 0.04). CONCLUSION: Higher lactation intensity was associated with more favorable biomarkers for type 2 diabetes, except for lower plasma adiponectin, after GDM delivery. Long-term follow-up studies are needed to assess whether these effects of lactation persist to predict progression to glucose intolerance.

Influence of breastfeeding during the postpartum oral glucose tolerance test on plasma glucose and insulin.

OBJECTIVE: To examine the effect of breastfeeding during the postpartum oral glucose tolerance test (OGTT) on maternal blood glucose and insulin among women with recent gestational diabetes mellitus. METHODS: Participants were enrolled in the Study of Women, Infant Feeding, and Type 2 Diabetes, a prospective observational cohort study of 1,035 Kaiser Permanente Northern California members who had been diagnosed with GDM and subsequently underwent a 2-hour 75-g OGTT at 6-9 weeks postpartum for the study enrollment examinations from 2008 to 2011. For this analysis, we selected 835 study participants who reported any intensity of lactation and were observed either breastfeeding their infants (ie, putting the infant to the breast) or not breastfeeding during the OGTT. RESULTS: Of 835 lactating women, 205 (25%) breastfed their infants during the 2-hour 75-g OGTT at 6-9 weeks postpartum. Mean (standard deviation) duration of breastfeeding during the OGTT was 15.3 (8.1) minutes. Compared with not having breastfed during the OGTT, having breastfed during the test was associated with lower adjusted mean (95% confidence interval) 2-hour glucose (mg/dL) by -6.2 (-11.5 to -1.0; P=.02), 2-hour insulin (microunits/mL) by -15.1 (-26.8 to -3.5; P=.01), and natural log 2-hour insulin by -0.15 (-0.25 to -0.06; P<.01), and with higher insulin sensitivity index0,120 by 0.08 (0.02-0.15; P=.02), but no differences in plasma fasting glucose or insulin concentrations. CONCLUSION: Among postpartum women with recent gestational diabetes mellitus, breastfeeding an infant during the 2-hour 75-g OGTT may modestly lower plasma 2-hour glucose (5% lower on average) as well as insulin concentrations in response to ingestion of glucose.

Lactation intensity and postpartum maternal glucose tolerance and insulin resistance in women with recent GDM: the SWIFT cohort.

OBJECTIVE: To 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 METHODS: We 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. RESULTS: Compared 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 -4.3 (-7.4 to -1.3) and -5.0 (-8.5 to -1.4), in fasting insulin (µU/mL) of -6.3 (-10.1 to -2.4) and -7.5 (-11.9 to -3.0), and in 2-h insulin of -21.4 (-41.0 to -1.7) and -36.5 (-59.3 to -13.7) (all P < 0.05). Exclusive or mostly breastfeeding groups had lower prevalence of diabetes or prediabetes (P = 0.02). CONCLUSIONS: Higher 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.