Type 2 diabetes is a chronic condition that affects the body’s ability to metabolize sugar, specifically glucose. Most of the cells in the body use glucose as an energy source. With type 2 diabetes, the cells ignore the effects of insulin (a hormone that regulates the movement of sugar into cells), and the body has a hard time producing enough insulin to maintain a normal glucose level. Untreated, this can be a life-threatening problem. For a discussion of diabetes in pregnancy, see this article.

Type 2 diabetes mellitus affects about 9 million adult women in the United States. Several studies have suggested that breastfeeding may protect against type 2 diabetes. One of these studies showed that the longer the duration of breastfeeding, the lower the risk of type 2 diabetes in young and middle-aged women. For each additional year, the risk of developing diabetes dropped by 15%. This protective effect was independent of other diabetes risk factors including body mass index, diet, exercise, and smoking status.1 

This effect may be due to the increased energy requirements of breastfeeding leading to lower overall blood glucose levels.2 It might also be that breastfeeding releases hormones that improve the cells’ response to insulin and reduce the overall strain on the endocrine system.3-5 For some women, breastfeeding helps out with weight loss, which can also help with diabetes risk.6, 7 Not every woman has this experience. Other studies have found that breastfeeding women have better function of the pancreas, the organ which produces insulin, and better control of blood glucose levels.5, 8


Adapted by Saneea Almas, MD from an original written by Sonia Shoukat, MD and Thomas W. Hale, PhD.


1. Stuebe AM, Rich-Edwards JW, Willett WC, Manson JE, Michels KB. Duration of lactation and incidence of type 2 diabetes. Jama. Nov 23 2005;294(20):2601-2610

2. Butte NF, Wong WW, Hopkinson JM. Energy requirements of lactating women derived from doubly labeled water and milk energy output. The Journal of nutrition. Jan 2001;131(1):53-58

3. Burnol AF, Leturque A, Ferre P, Kande J, Girard J. Increased insulin sensitivity and responsiveness during lactation in rats. The American journal of physiology. Nov 1986;251(5 Pt 1):E537-541

4. Jones RG, Ilic V, Williamson DH. Physiological significance of altered insulin metabolism in the conscious rat during lactation. The Biochemical journal. Jun 1 1984;220(2):455-460

5. Kjos SL, Henry O, Lee RM, Buchanan TA, Mishell DR, Jr. The effect of lactation on glucose and lipid metabolism in women with recent gestational diabetes. Obstetrics and gynecology. Sep 1993;82(3):451-455

6. Brewer MM, Bates MR, Vannoy LP. Postpartum changes in maternal weight and body fat depots in lactating vs nonlactating women. The American journal of clinical nutrition. Feb 1989;49(2):259-265

7. Butte NF, Hopkinson JM. Body composition changes during lactation are highly variable among women. The Journal of nutrition. Feb 1998;128(2 Suppl):381S-385S

8. McManus RM, Cunningham I, Watson A, Harker L, Finegood DT. Beta-cell function and visceral fat in lactating women with a history of gestational diabetes. Metabolism: clinical and experimental. Jun 2001;50(6):715-719