USA: Study Links Lactation Duration to Lower Risk of Type 2 Diabetes

A recent study in the journal Diabetes Care has found a direct link between lactation duration and a lower risk of type 2 diabetes. According to the study, women with a history of gestational diabetes who lactate for a longer duration are at a lower risk of developing type 2 diabetes in later life.

Gestational diabetes, or diabetes during pregnancy, is characterized by high blood sugar and occurs in approximately 1 in 20 pregnant women.

Sylvia H. Ley, from the Department of Epidemiology at Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, and colleagues examined the association of lactation duration with incident type 2 diabetes among women with a history of gestational diabetes mellitus.

For this purpose, the researchers monitored 4,372 women with a history of gestational diabetes who participated in the Nurses' Health Study II for incident type 2 diabetes over 25 years up to 2017. Lactation history was obtained through follow-up questionnaires to calculate lactation duration. Follow-up blood samples were collected from a subset of these women at a median age of 58 years through the Diabetes & Women's Health Study.

873 incident cases of type 2 diabetes were documented during 87,411 person-years of follow-up.

Key Findings of the Study

• Longer duration of lactation was associated with a lower risk of type 2 diabetes for both total lactation (hazard ratio 1.05 for up to 6 months, 0.91 for 6–12 months, 0.85 for 12–24 months, and 0.73 for >24 months, compared with 0 months) and exclusive breastfeeding after adjustment for age, ethnicity, family history of diabetes, parity, age at first birth, smoking, diet quality, physical activity, and prepregnancy BMI.
• Longer duration of lactation was also associated with lower HbA1c, fasting plasma insulin, and C-peptide concentrations among women without type 2 diabetes at follow-up.

"Longer duration of lactation is associated with a lower risk of type 2 diabetes and a favorable glucose metabolic biomarker profile among women with a history of GDM," wrote the authors.

"The underlying mechanisms and impact on diabetes complications, morbidity, and mortality remain to be determined," they concluded.

The study, "Lactation Duration and Long-term Risk for Incident Type 2 Diabetes in Women With a History of Gestational Diabetes Mellitus," is published in the journal Diabetes Care.

DOI: https://doi.org/10.2337/dc19-2237