The Effect of Lactation on Insulin Sensitivity and Lipolysis in Women

The Effect of Lactation on Insulin Sensitivity and Lipolysis in Women

This purpose of this study is to investigate whether lactation improves insulin sensitivity and increases lipolysis in women.

There are two aims that this research will address.

In Aim 1, the research question is "Does lactation improve insulin sensitivity and increase lipolysis in women?" In this Aim, researchers will assess whether lactation amongst women with a history of gestational diabetes mellitus (GDM) will improve whole body insulin sensitivity as well as increase whole body lipid turnover by using hyperinsulinemic-euglycemic clamps combined with [6,6-2H]-glucose and [2H5]-glycerol infusions. These stable, non-radiating isotopes have been used extensively and safely to study the mechanisms of insulin resistance amongst non-pregnant as well as pregnant humans; however, these techniques have not previously been applied to the study of insulin sensitivity during lactation. Therefore, the goals will be two-fold: 1) to determine whether lactation induces similar changes in insulin sensitivity in humans as in mice and 2) to pilot the feasibility of performing larger, more detailed metabolic studies in this population of women post-partum.

The second aim (Aim 2) will use a retrospective chart review of women with a history of GDM who had an oral glucose tolerance test (OGTT) 6-8 weeks post-partum as part of standard of care.

The focus of this protocol registration will be Aim 1.

Inclusion Criteria:

• A history of GDM (as defined as the American Diabetes Association criteria)
• Delivered a singleton, live birth at ≥ 35 weeks gestation within the past 18 months
• HbA1C < 6.5% at time of screening
• Delivery within the past 18 months
• Breast Feed Group: exclusively or mostly breast-fed (< 6 ounces of formula/24 hours at 6-9 weeks of delivery) for at least 4-6 months

Exclusion Criteria:

• Currently lactating or lactation within the past 1 month at the time of the screening visit
• Diagnosis of diabetes (T1D or T2D) prior to pregnancy
• Current use of any glucose-lowering agents
• Pregnancy related medical problems including preeclampsia
• Major congenital fetal anomalies
• Creatinine > 1.5mg/dL, Hematocrit < 35%, ALT and AST > 2.5X upper limit of normal
• Known psychiatric disorders, alcohol abuse, HIV, hepatitis, renal disease, hepatic disease, untreated heart disease, untreated thyroid disease, active systemic infection or malignancy
• Illicit drug use (by the participant's self-report)
• History of post-partum depression
• Use of weight loss supplements or dieting 6 months prior to study
• Corticosteroid or opiate use within 6 months of study