Insulin injection. 13-year-old girl injecting herself in the abdomen with insulin. She has diabetes mellitus. This is a disorder affecting glucose sugar metabolism, where the sugar is not oxidised due to a lack of the hormone insulin, secreted by the pancreas in healthy individuals. In diabetics, unused sugar accumulates in the blood and the urine. Fats are utilised as an alternative energy source, which leads to a build-up of ketones in the blood that may eventually cause convulsions and diabet