Insulin is a hormone produced by the beta cells in the pancreas. It plays a key role in controlling the uptake and use of glucose, the body’s main source of energy. It also plays an important role in protein synthesis and lipid (triglyceride) storage. If a person does not produce enough insulin or is resistant to its effects, the glucose will remain in the blood (hyperglycemia) and the body’s cells will not have enough energy to function properly.
However, in individuals who produce or receive too much insulin, blood glucose levels will drop and the person will experience symptoms of hypoglycemia (tremors, palpitations, sweating, anxiety, hunger, nausea, etc.). Insulin levels must be interpreted with glucose levels measured simultaneously and occasionally C peptide levels.
Normal levels of glucose and insulin indicate a pancreas that is probably functioning normally. High insulin levels with normal or slightly high glucose levels indicate insulin resistance (obesity, some type 2 diabetic patients). A very high glucose level accompanied by a low insulin level indicates an impaired pancreas (diabetes, pancreatitis, etc.). Low glucose levels with normal or high insulin levels are consistent with overactive adrenal glands (Cushing’s syndrome), excessive administration of exogenous insulin, or insulinoma (pancreatic tumour secreting insulin), for example.