Scientists from Imperial College London who study the possible connection between diabetes and melatonin–the hormone that regulates our internal “body clock”–have found that a genetic mutation in the receptor for melanin could elevate a person’s risk of developing type 2 diabetes. Researchers focused their attention on the MT2 melatonin receptor gene in over 7,000 people.
Common vs. Rare Mutations: MT2 Receptor
The team identified 40 variants associated with type 2 diabetes. Some genetic mutations are common, while others are relatively rare. Earlier research (2008) has shown that people with common variations in the gene for the MT2 melatonin receptor possess only a minimal increase in risk for type 2 diabetes. However, this recent study (published in Nature Genetics) reveals that a person who has any of the four rare mutations in the gene for the MT2 receptor can have up to six times the increased risk of getting type 2 diabetes. The four rare mutations of the MT2 receptor gene actually render the receptor incapable of responding to the hormone melatonin.
What Is Melatonin?
Melatonin is a hormone that is secreted by the pineal gland near the brain. Melatonin is commonly known as the “body clock” hormone because of its role in the body’s circadian rhythm. The circadian rhythm is an internal cycle of biochemical, physiological, and behavioral processes that spans approximately 24 hours and exists in all living organisms. External stimuli like temperature, nutrition, medications can set or alter circadian rhythms. The light/dark or day/night cycle of the earth is one of the most essential regulators for the circadian rhythm. When it is dark, light receptors perceive the darkness and trigger the production of melatonin.
How Melatonin and Diabetes May Be Connected
Melatonin, in addition to preparing the body’s internal clock for sleep, controls the release of insulin from the pancreas, which in turn regulates the level of sugar in the blood. Genetic mutations in the gene for the MT2 receptor might upset the connection between insulin release and the body clock, thereby causing abnormalities in blood sugar level control and contributing to the onset of type 2 diabetes.
While the findings of the study could improve assessment of a individual’s risk of diabetes, it bears noting that the research has shown a link but not a cause-effect relationship between melatonin and diabetes.