Disruption of the clock components CLOCK and BMAL1 leads to hypoinsulinaemia and diabetes

Clocking on to diabetes During periods of feeding, pancreatic islets secrete insulin to maintain glucose homeostasis — a rhythmic process that is disturbed in people with diabetes. Experiments in mice now show that the pancreatic islets contain their own biological clock, which orchestrates insulin secretion during the sleep–wake cycle. The transcription factors CLOCK and BMAL1 are vital for this process, and mice with defective copies of the genes Clock and Bmal1 develop hypoinsulinaemia and diabetes. By demonstrating that a local tissue clock integrates circadian and metabolic signals in pancreatic β-cells, this work suggests that circadian analyses are crucial for deeper understanding of metabolic phenotypes, as well as for the treatment of metabolic diseases such as type 2 diabetes.