The cause of fluctuating blood sugar levels in diabetics. The number of people with diabetes is growing at an alarming rate. Blood sugar levels begin to fluctuate when the hormone known as insulin ceases to function as it should. A less well known fact is that the concentrations of the hormone glucagon are also disturbed and contribute to the peaks and troughs in the levels of blood sugar. Patrik Rorsman is investigating how the secretion of glucagon is regulated in the body and what role it plays in diabetes.