Migraine Fact Sheets

Hypoglycaemia and Migraine

Hypoglycaemia is the medical condition of having an abnormally low blood sugar (glucose) level, and can be responsible for triggering or exacerbating migraines and headaches.

The importance of blood-glucose

We need energy to function, and most of this energy comes from consuming carbohydrates (sugars). Our bodies convert these carbohydrates into glucose (which is easier to use), and is then carried in the blood to whichever parts of the body need it. The brain requires a continuous supply of glucose from the blood in order to function, and if glucose levels drop (as in hypoglycaemia) the brain is one of the first organs affected.

Maintaining blood-glucose levels

Our bodies have to keep their blood-glucose levels from becoming too low or too high, and they do this using two fast-acting hormones: insulin and glucagon. When blood-glucose levels get too high, insulin acts to bring them down; when levels get too low, glucagon pushes them back up.

Causes of hypoglycaemia

If we don’t eat enough calories for our bodies’ needs, then our blood-glucose levels drop too low. This can happen if we skip meals, fast, diet, or exercise on insufficient food. Eating a high-sugar meal can cause ‘reactive hypoglycaemia’, because the sudden rise in blood-glucose from the sugary food triggers an over-production of insulin, which in turn makes the blood-glucose levels fall too low. If diabetes patients inject too much insulin into their bodies, it can also cause their blood-glucose levels to fall too low.

Symptoms of hypoglycaemia

The brain not receiving enough glucose causes most of the symptoms of hypoglycaemia, which include: headache, migraine, confusion, nausea, sweating, faintness, and hypothermia. If the hypoglycaemia is very severe and prolonged, it can even cause loss-of-consciousness and death, although this is rare.

Hypoglycaemic headaches and migraines

Fasting, eating high-sugar foods, dieting too rigorously, and skipping meals can all trigger, or make people more likely to have a headache or migraine. Even delayed or irregular meals can make a difference. This is usually due to people’s blood-glucose levels falling too low.

Headaches produced from going without food are often quite severe and accompanied by mild nausea. There is also a similarity between some of the symptoms of missing a meal and the early warning signs (premonitory) of a migraine attack, such as: yawning, pallor, sweating, headache, a craving for sweet things, and mood changes.

Headaches and migraines caused by fasting may not always be due to hypoglycaemia, for example they can be caused by the stress-hormones released by the body during fasting. They are also often triggered by dehydration and lack of sleep. Changes in caffeine intake, for example by drinking less tea or coffee, and changes in smoking frequency also often trigger headaches and migraines.

Hypoglycaemia tests

A prolonged glucose tolerance test, which measures your ability to process sugar, can be used to determine if you are hypoglycaemic. In this test, you will be given a measured amount of sugar to eat, and then your blood-glucose levels will be monitored over several hours. Alternatively, a tiny sample of blood can be taken while you are unwell, and your glucose level measured from that.

Treating hypoglycaemic headaches and migraines

If your headaches/migraines appear to be triggered or exacerbated by low blood-glucose levels, you should be able to keep them under control by paying close attention to your diet. Small, frequent, low-sugar meals are ideal. Make sure you never miss breakfast or skip meals, and if you usually have sandwiches for lunch try having proper meals instead. If you have lunch early, have an afternoon snack so you don’t get hungry.

If you have hypoglycaemic headache that starts when you wake up, it can sometimes be prevented by having breakfast cereal last thing at night. This should be of high-fibre to prolong the glycaemic effect.

Also, try and improve the quality of your food by eating a balanced diet with more unrefined foods, fresh fruit and vegetables, and cut down on cakes, biscuits, ice cream and anything which makes you consume large amounts of sugar over a short period of time. Also, it may help to add more protein to your diet, and try to avoid flavoured, or pre-cooked foods. The naturally-occurring sugars in unrefined food are digested much more slowly than those in refined food, which means that glucose is released into the bloodstream more slowly, and so is less likely to stimulate the over-production of insulin that leads to hypoglycaemia.

If you are dieting, plan to lose a smaller amount of weight over a longer period of time. This is a better way to diet, since it is easier to keep the weight off once you’ve finished.

Stress and alcohol can both interfere with your metabolism, so it is important to make time for relaxation and sleep, and be careful how much alcohol you drink. Caffeine can also have an effect so gradually cut down on tea, coffee, chocolate, and other caffeine-containing products (e.g. Red Bull, Coca-Cola, Pepsi, and Dr. Pepper).

These simple adjustments can make a real difference to the frequency and severity of your headaches or migraines if they are triggered by hypoglycaemia, and your doctor can also help you find ways to treat them.

Headaches and migraines can often be caused by several different factors, and some people require a combination of treatments which address each factor, to effectively manage their condition.

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