Low blood sugar in people without diabetes

Low blood sugar (hypoglycaemia) can happen in people who don't have diabetes. It can be reactive, coming on after eating, or fasting. Reactive hypoglycaemia is often linked to certain illnesses.

Symptoms

In both types the symptoms are like those of low blood sugar in diabetes: hunger, nervousness, sweating, shaking, loss of balance, light-headedness, sleepiness, confusion, difficulty speaking, anxiety and weakness.

If low blood sugar is diagnosed, the doctor will run lab tests to find the cause, checking insulin and other markers of how the body uses energy.

Reactive hypoglycaemia

In reactive hypoglycaemia, blood sugar drops within four hours of eating.

Diagnosis

To diagnose reactive hypoglycaemia, the doctor will:

Ask about the signs and symptoms.
Check the blood glucose level while the symptoms are present. The doctor sends a blood sample to the lab: home glucose meters can't be used to diagnose reactive hypoglycaemia.
See whether the symptoms go quickly once blood glucose is back to 70 mg/dl or higher, after eating or drinking.

A blood sugar below 70 mg/dl during symptoms after a meal, with relief once it rises, confirms the diagnosis. The glucose tolerance test is no longer used to diagnose reactive hypoglycaemia, because it can bring on severe symptoms and harm the patient.

Causes and treatment

In most cases the cause is still uncertain. Some researchers think some people's bodies are more sensitive to certain hormones, such as adrenaline (epinephrine), which causes the symptoms of low blood sugar. Others think it comes from too little of the hormone glucagon.

Some causes are known. Stomach surgery, for example, can cause low blood sugar because food passes too quickly into the small intestine. A rare inherited enzyme deficiency that causes fructose intolerance can also cause reactive hypoglycaemia.

To ease reactive hypoglycaemia, specialists advise:

Eat small meals and snacks about every 3 hours.
Exercise regularly.
Eat a varied diet, including meat, fish or other sources of protein, starchy foods such as potatoes, rice, bread and grains, and vegetables and fruit.
Eat foods rich in fibre.
Avoid or cut down on sugary foods, especially on an empty stomach.

Although specialists often recommend a high-protein, low-carbohydrate diet, studies have shown that an unbalanced diet doesn't help manage reactive hypoglycaemia.