A FAULTY internal clock in the cells in the pancreas that produce insulin could be behind type 2 diabetes – a condition in which the body is unable to produce or use insulin properly.
The finding suggests that disruption of natural night and day cycles through artificial lighting may be a factor in the emergence of type 2 diabetes in adults. It also fits with studies showing that shift workers are unusually prone to the condition.
Insulin is produced by beta cells to control glucose levels in the blood. of Northwestern University in Evanston, Illinois, and colleagues grew mouse beta cells in the lab to monitor insulin secretion. They found that beta cells lacking circadian “clock” genes produced 50 per cent less insulin, showing that these genes are essential for normal insulin production (Nature, ). Likewise, live mice with disrupted clock genes rapidly developed type 2 diabetes.
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The next step, says Bass, is to identify the “switch” in beta cells that responds to the clock, and use it to develop a treatment.
“The key thing the researchers have shown is that disruption of this internal clock causes a defect in insulin secretion,” says Noel Morgan of the Peninsula Medical School in Exeter, UK, who studies type 1 diabetes, in which the body’s own immune system destroys its beta cells.
“Disruption of the internal clock in insulin-producing cells causes a defect in insulin secretion”
In a separate study, Morgan showed that beta cells multiplied 10 times as fast in children newly diagnosed with type 1 diabetes as in healthy individuals (Diabetologica, ). He believes that if the faulty immune response can be stopped, it might be possible to persuade beta cells to multiply and restore normal levels of insulin production.
