Accumulating research supports a role for prolactin in insulin secretion and sensitivity. Between 1989 and 1990 and between 1996 and 1999 researchers recorded total plasma prolactin via immunoassay in 8615 women who did not have T2D or cardiovascular disease at study onset. A subset of 988 women provided a second sample between 2000 and 2002. Researchers measured baseline bioactive prolactin levels and evaluated the association with T2D risk in a subset of 2478 women using the Nb2 lymphoma cell bioassay.
Researchers documented 699 cases of incident T2D during follow-up. The results suggested an inverse relationship between total circulating prolactin levels and the risk for T2D. Multivariable hazard ratios of T2D, when comparing the higher quartiles to the lower quartile of prolactin concentrations, were 0.95 (95% CI, 0.75-1.19), 1.01 (95% CI, 0.80-1.28), and 0.73 (95% CI, 0.55-0.95), respectively.
This inverse relationship was observed in both pre- and postmenopausal women and remained significant after adjusting for multiple reproductive and hormonal factors. The hazard ratios for T2D when comparing extreme quartiles were 0.80 (95% CI, 0.52-1.22) and 0.65 (95% CI, 0.43-0.98), respectively.
The investigators concluded that “a normally high circulating total prolactin concentration was associated with a lower type 2 diabetes risk within 9 to 10 years of follow-up since blood draw in US women.” Study limitations included a high rate of white, middle-aged participants with limited ethnic involvement.
Li J, Rice MS, Huang T, et al. Circulating prolactin concentrations and risk of type 2 diabetes in US women [published online October 11, 2018]. Diabetologia. doi:10.1007/s00125-018-4733-9