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

Study of Women, Infant feeding, and Type 2 diabetes mellitus after GDM pregnancy (SWIFT), a prospective cohort study: methodology and design

<p>Abstract</p> <p>Background</p> <p>Women with history of gestational diabetes mellitus (GDM) are at higher risk of developing type 2 diabetes within 5 years after delivery. Evidence that lactation duration influences incident type 2 diabetes after GDM pregnancy is based on one retrospective study reporting a null association. The Study of Women, Infant Feeding and Type 2 Diabetes after GDM pregnancy (SWIFT) is a prospective cohort study of postpartum women with recent GDM within the Kaiser Permanente Northern California (KPNC) integrated health care system. The primary goal of SWIFT is to assess whether prolonged, intensive lactation as compared to formula feeding reduces the 2-year incidence of type 2 diabetes mellitus among women with GDM. The study also examines whether lactation intensity and duration have persistent favorable effects on blood glucose, insulin resistance, and adiposity during the 2-year postpartum period. This report describes the design and methods implemented for this study to obtain the clinical, biochemical, anthropometric, and behavioral measurements during the recruitment and follow-up phases.</p> <p>Methods</p> <p>SWIFT is a prospective, observational cohort study enrolling and following over 1, 000 postpartum women diagnosed with GDM during pregnancy within KPNC. The study enrolled women at 6-9 weeks postpartum (baseline) who had been diagnosed by standard GDM criteria, aged 20-45 years, delivered a singleton, term (greater than or equal to 35 weeks gestation) live birth, were not using medications affecting glucose tolerance, and not planning another pregnancy or moving out of the area within the next 2 years. Participants who are free of type 2 diabetes and other serious medical conditions at baseline are screened for type 2 diabetes annually within the first 2 years after delivery. Recruitment began in September 2008 and ends in December 2011. Data are being collected through pregnancy and early postpartum telephone interviews, self-administered monthly mailed questionnaires (3-11 months postpartum), a telephone interview at 6 months, and annual in-person examinations at which a 75 g 2-hour OGTT is conducted, anthropometric measurements are obtained, and self- and interviewer-administered questionnaires are completed.</p> <p>Discussion</p> <p>This is the first, large prospective, community-based study involving a racially and ethnically diverse cohort of women with recent GDM that rigorously assesses lactation intensity and duration and examines their relationship to incident type 2 diabetes while accounting for numerous potential confounders not assessed previously.</p