Hormone that helps breastfeed also protects against diabetes


Higher levels of prolactin hormone in women were associated with a lower risk of diabetes

High levels of the hormone prolactin (within physiological range) have been associated with lower risk of developing type 2 diabetes (T2D).

This is according to new research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]). The study is by Dr Jun Li, Harvard T.H. Chan School of Public Health, Boston, MA, USA, and colleagues.

Prolactin, a multifunctional hormone, is involved in regulating insulin sensitivity and blood glucose stability in experimental studies. It helps regulate growth of insulin-producing cells in the pancreas, and is also involved in lactation, reproduction, metabolism, immune regulation and water balance (osmoregulation).

In healthy women, circulating prolactin levels change in response to pregnancy, lactation, physical activity, sleep and stress.

In healthy women, circulating prolactin levels change in response to pregnancy, lactation, physical activity, sleep and stress.

In the study, the authors analysed the prospective relationship between circulating prolactin concentrations and type 2 diabetes risk in two large studies of women: the Nurses’ Health Study (NHS) and a sister study, NHSII, with up to 22 years of follow-up.

Total plasma prolactin was measured in 8615 women free of T2D and cardiovascular disease, and cancer at baseline blood collection time (NHS 1989-1990; NHSII 1996-1999). Measurements were also taken in a subset of 998 NHS women providing a second blood sample during 2000-2002.

A total of 699 cases of T2D developed across the follow-up period. The authors found that total plasma prolactin levels were inversely associated with type 2 diabetes risk; women in the group with the highest 25% of prolactin levels were 27% less likely to develop T2D than those in the lowest 25%.

The associations were similar regardless of the women’s menopausal status and other risk factors. Additional adjustment for sex and growth hormones, adiponectin, and inflammatory and insulin markers did not significantly alter the results.

The inverse association of total prolactin with type 2 diabetes was significant during the first 9-10 years after blood samples were taken, but faded over time.

The authors say that this attenuation in association may be explained by natural variations in circulating prolactin levels over time, or possibly by a reduction in prolactin caused by impaired glucose tolerance (reverse causation).

The authors note that the studies involved mostly white middle-aged women, so the results are not generalisable to men or to people of other age groups or ethnicities.

They say: “In a large prospective cohort study of US women, total circulating prolactin concentrations within the physiological range were inversely associated with type 2 diabetes risk, especially during the first 9-10 years of follow-up after blood samples were taken.”


  1. I was diagnosed as type 2 last year, my weight was 125kg, my doctor wanted me to start insulin and encouraged a diet with an alarming amount of carbs, so I went to boots and bought a blood sugar tester that I used every day, and started on a Atkins type diet. I.e no carbs….. and when I say no carbs I really mean none. So lots of meats and fish, eggs etc. I also got some useful information here http://mydiabetesway.com/the-16-best-foods-to-control-diabetes I gradually started loosing weight at a rate of 3kg per month and Im now 94kg, I have never taken insulin and in a few months I will be my target weight. my lifestyle can never go back to carbs, but I can have some nowerdays without my blood sugar increasing, so if I want a curry I can have a Nan bread with it but no rice chips etc. And to be honest when you cut out carbs you can eat a lot of really tasty things that help lose weight a fry up without the beans is fine, lamb chops and kebabs without the bread etc. The only downside is because of the extra fat intake I need to be doing daily cardio. I really believe doctors are offered too many incentives by drug companies and tend to love writing prescriptions instead of encouraging a positive change in our lifestyles.

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