Causes
Hypoglycemia can be caused by medications. Medication-related hypoglycemia occurs most commonly in people who have diabetes, especially type 1 diabetes (a type of diabetes where the pancreas does not make insulin). In both type 1 and type 2 diabetes it can occur when someone is given too much insulin or other medications for diabetes that promote the release of insulin from the pancreas in relation to their current level of exercise and diet. This can drastically lower blood sugar, resulting in hypoglycemia. There are also other medications that can cause hypoglycemia in people with diabetes and people that do not have diabetes, such as certain medications for high blood pressure (e.g., atenolol*, metoprolol, propranolol), certain antidepressants (e.g., phenelzine, tranylcypromine), quinine, haloperidol, and trimethoprim - sulfamethoxazole.
Other types of hypoglycemia include fasting hypoglycemia and reactive hypoglycemia. In fasting hypoglycemia, a person gets low blood sugar if they haven't eaten for a while. Reactive hypoglycemia is low blood sugar that occurs after eating, usually due to eating a meal high in carbohydrates. This causes the blood sugar to rise rapidly, which in some cases may stimulate excess secretion of insulin. People may also have reactive hypoglycemia if they have trouble digesting fructose and galactose (two types of sugars found in foods), or leucine (an amino acid found in foods). It may also occur after some types of stomach surgery, as this may cause sugars to be absorbed too quickly, leading to excessively high insulin levels, which can cause hypoglycemia.
Hypoglycemia can also be caused by a problem with the pituitary or adrenal glands, pancreas, kidneys, or liver. The pituitary gland controls the body's production of some of the hormones needed to raise the body's blood sugar levels if they fall too low. These hormones include cortisol, which is released from the adrenal glands; glucagon, which is released from the pancreas; and adrenaline, which is released from the adrenal gland medulla. These hormones all help raise blood sugar levels. If they are not working properly, this could cause hypoglycemia.
Hypoglycemia can also result when the liver can't properly store carbohydrates or convert them into glucose. A tumor on the pancreas can also cause hypoglycemia by causing too much insulin to be released.
People who drink alcohol excessively (without eating) can develop severe hypoglycemia. In cases of severe kidney dysfunction, hypoglycemia might also develop.