Type 2 diabetes: Study explains link to sleep hormone melatonin
Researchers have discovered that increasing levels of the sleep hormone melatonin reduces the ability of insulin-producing cells to release insulin. Also, they found the effect is stronger in people who carry a particular gene variant that is linked to higher risk for type 2 diabetes.
The study, led by Lund University in Sweden, is published in the journal Cell Metabolism.
The findings mark the culmination of work that goes back to 2009, when Lund researchers showed that a variant of the gene that codes for the protein known as melatonin receptor 1B (MTNR1B) increases the risk for type 2 diabetes.
Melatonin is a hormone that helps to maintain our day-night cycle, or circadian rhythm, by regulating other hormones. The amount of melatonin in our blood varies through the day. It is affected by light and peaks during the darkest time, at night.
Insulin is a hormone that regulates blood sugar levels. It is produced and released by the beta cells of the pancreas, in response to spikes in blood sugar, such as during digestion.
In type 2 diabetes, which accounts for nearly 90 percent of diabetes, the body either does not produce enough insulin, or cells become less effective at responding to it, which increases demand on the beta cells to produce more. Both of these result in increased levels of blood sugar, which eventually causes serious damage to organs.
In the new study, the researchers worked with lab-cultured beta cells and mice to show that insulin-producing cells respond to increased levels of melatonin by reducing the amount of insulin they release. These signals are conve Continue reading