Metformin (Glucophage, Glumetza) is a drug for the treatment of diabetes and you will not find any scientific articles if you google “metformin and migraine”. However, I’ve been prescribing metformin to some of my migraine patients with some success. In the absence of controlled trials to prove its efficacy, one can argue that those patients who improved are experiencing the placebo effect. However, there are two possible ways by which metformin can help prevent migraines.
Obesity does not predispose one to migraines, but in those who do suffer from migraines increased weight is associated with an increased frequency and severity of migraine attacks. Since metformin is proven to help reduce weight, this could be one of the mechanisms by which it improves migraines. Weight loss due to metformin has been shown to be sustainable for up to 10 years.
The second possible mechanism is metformin’s direct effect on inflammation, which is one of the major mechanisms involved in migraines.
I usually prescribe metformin to patients who are overweight and I prefer metformin to the most popular migraine preventive drug, topiramate (Topamax). Topiramate can cause difficulty with memory, kidney stones, osteoporosis, acute glaucoma and other serious side effects, while metformin only occasionally causes nausea. If nausea does occur, changing to a slow release form of metformin (metformin ER) usually helps. Metformin can also cause a drop in vitamin B12 level, so it is worth prescribing a vitamin B12 supplement along with metformin. Metformin should not be prescribed to patients with impaired kidney function, so a baseline blood test is necessary.
Another group of patients I prescribe metformin to are those who are not obese, but report having migraines due to low blood sugar – either when they are hungry or after eating carbohydrate-rich foods, which can lead to a drop in blood glucose (so called reactive hypoglycemia). They often report feeling less hungry and not needing to eat frequently to avoid migraines. Metformin works by regulating the release of glucose from the liver to maintain a steady level of glucose in the blood. This is why this drug does not cause a drop in blood glucose level like other diabetes medications and can be taken by non-diabetics.
The starting dose of metformin is 500 mg a day and if necessary, it can be increased to 1,000 and up to 2,000 mg a day.
Metformin has another unproven potential benefit – it may make you live longer. For now, it’s been shown to be the case only in mice, fruit flies and worms.
