Glucokinase (GCK) is a gene which plays an important role in recognising how high the blood glucose is in the body. It acts as the “glucose sensor” for the pancreas, so that when the blood glucose rises, the amount of insulin produced also increases. This means that the blood glucose does not become too high if glucokinase is functioning normally. Changes in the GCK gene can lead to increases in blood glucose and affected people may be diagnosed with diabetes although this rise in blood glucose is mild and usually does not need treatment. Glucokinase diabetes is one of the familial diabetes types that together are often called MODY (maturity onset diabetes of the young).