In most cases hypoglycaemia occurs in people with diabetes, although in rarer cases it can occur due to other underlying conditions.
Causes of hypoglycaemia in people with diabetes
Overdose of diabetes medication
A common cause of hypoglycaemia is taking too much insulin medication for your current needs.
A drop in blood glucose levels can also happen when you take too much oral hypoglycaemia medication, such as sulphonylurea, which causes a release of insulin. This medication is often used in treating type 2 diabetes to lower blood glucose.
Exercise, food and alcohol
For people with type 1 diabetes, maintaining the correct blood glucose level involves balancing between the amount of insulin you inject, the amount of food you eat and the amount of energy you burn during exercise.
Hypoglycaemia may occur if you have taken your dose of insulin as usual but your carbohydrate intake is lower than normal, or has been used up more quickly. This may happen if you delay or miss a meal or snack, do not eat enough carbohydrate, or do more exercise than usual.
Hypoglycaemia may also occur in people with diabetes who have been drinking alcohol on an empty stomach, without food.
Causes of hypoglycaemia in people without diabetes
Hypoglycaemia (even mild cases) is very rare in people who are not on insulin or sulphonylurea. The possible causes of hypoglycaemia in people without diabetes are outlined below.
Reactive hypoglycaemia
Too much insulin in the blood in people without diabetes type 1 is commonly caused by their pancreas producing too much insulin after a large carbohydrate-based meal. This is known as reactive hypoglycaemia. The reason for it is not clear, although it is thought to be more common in people who are overweight or have had gastric bypass surgery, and those with type 2 diabetes.
In rare cases, a benign (non-cancerous) tumour in the pancreas may cause an overproduction of insulin, or the tumour itself may use up too much glucose.
Other health conditions
Other possible causes of hypoglycaemia in non-diabetics are:
- fasting or malnutrition – you are not consuming enough nutrients for your body to function properly
- binge drinking or heavy drinking of alcohol
- Addison's disease – a disorder of the adrenal glands
- certain medication – hypoglycaemia has been known to occur in people taking quinine (for malaria), salicylates (for rheumatic disease) and propranolol (for high blood pressure)
- severe illnesses affecting the liver, kidneys or thyroid gland
