studies have shown that prolactin is responsible for regulating insulin
sensitivity and blood glucose stability. Moreover, it is also involved in the
growth regulation of pancreatic insulin-secreting cells.
and occurs due to insulin resistance,
where the body does not use insulin properly to maintain the level of blood
glucose within normal limits. This results in elevated blood glucose levels,
which is technically termed as hyperglycemia. In T2DM, the pancreas makes extra
overcome the insulin resistance. But, over time it is not able to keep up and
make enough insulin to keep the blood glucose within normal levels.
This was a large
prospective study that involved 22 years of follow-up. Data on blood levels of
circulating total prolactin and risk of T2DM were analyzed. This involved two
large-scale studies in women, which included the Nurses' Health Study (NHS) and
the associated NHS-II.
levels were measured at baseline in both groups (NHS: 1989-1990; NHS-II:
1996-1999). These included 8,615 women who did not suffer from T2DM,
cardiovascular disease or cancer. Blood was collected from a subset of 998
women in the NHS group for a second time during 2000-2002.
During the follow-up
period, 699 women developed T2DM. It was found that total prolactin levels
were inversely correlated with the risk of occurrence of T2DM i.e. higher
the levels of prolactin, lower the risk of developing T2DM
. The study showed
that women in the group with the highest 25% levels of prolactin were 27% less
likely to develop T2DM than those in the bottom 25% levels of prolactin.
was not influenced by the menopausal status of women or other risk factors.
Importantly, the results did not change even after adjustments were made for
sex, growth hormone levels, adiponectin levels as well as inflammatory and
insulin biomarkers. This inverse relationship between total prolactin levels
and T2DM risk remained significant for approximately the first decade
post-bleeding, but gradually waned thereafter.
The authors are of
the opinion that the decreased association between the two parameters could be
due to natural fluctuations in the prolactin levels in the blood. Alternately,
prolactin levels could be reduced by impaired glucose tolerance.
indicated that since the study was conducted on white middle-aged women, the
results were not translatable to men or to women of different age groups or
other ethnic backgrounds.
The authors say:
"In a large prospective cohort study of US women, total circulating prolactin
concentrations within the physiological range were inversely associated with
T2DM risk, especially during the first 9-10 years of follow-up after blood
samples were taken."
They added: "Our
epidemiological observations, coupled with previous population data and
emerging experimental evidence, support a potential protective role of
prolactin (within the biologically normal range) in the development of T2DM
risk in women. Future studies are warranted to understand the biological
mechanisms underlying this association, which may lead to the development of
new strategies for early prevention and treatment of T2DM."
- Circulating prolactin concentrations and risk of type 2 diabetes in US women - (http://diabetologia-journal.org/wp-content/uploads/2018/09/Li.pdf)