A healthy baby's body usually has very careful control of blood sugar levels. Insulin is the main hormone in the body that regulates blood sugar. Sick babies may have poor insulin function or low amounts, which causes poor control of the blood sugar.
There can be specific causes of ineffective or low insulin, such as infection, liver problems, hormone problems, and some medications. Rarely, babies may actually have diabetes, with low insulin levels that result in high blood sugars.