An international research team has identified a new gene variant that is associated with elevated fasting glucose levels and a high risk for Type II diabetes. The gene has been shown to mediate insulin secretion indirectly via the release of melatonin. This previously unknown relationship between the sleep-wake rhythm and the fasting glucose level opens up new possibilities for treatment that go beyond the current symptomatic therapies.
The finding was made by the MAGIC Consortium (Meta-Analyses of Glucose and Insulin-related traits Consortium), which, by combining the data from 13 case-control clinical studies with over 18,000 diabetic and 64,000 non-diabetic study participants, was able to identify a variant of the MTNR1B gene. The MTNR1B gene is associated with both elevated fasting glucose levels as well as an elevated risk for Type II diabetes.
The MTNR1B gene is expressed in insulin-producing islet cells, among others, and encodes one of the two known melatonin receptors. It is assumed that this receptor inhibits the release of insulin via melatonin. Melatonin levels in the body are high at night and decline in daylight, whereas the insulin level is higher during the day than in the night. Taken together, these new data implicate an association between the sleep-wake rhythm, the so-called circadian rhythm, and fasting glucose levels, which was not known before.
In the light of this association, researchers at the Helmholtz Zentrum München are now working to uncover the role melatonin plays in the regulation of insulin secretion, fasting glucose levels and the development of diabetes.