Headache: Interview with Dr. Charles Matthews
Director, the North Carolina Comprehensive Headache Clinic
Can hypoglycemia cause headaches?
Q- Dr. Matthews, this issue of Health and Healing is about diabetes. As Director of the Headache Clinic, have you seen any connections between headaches and diabetes?
Dr. Matthews: I'll try to answer that interesting question in a minute, but first let me review some facts about diabetes. The word "diabetes" is derived from the Latin and originally means "passing through", referring to the passing of large amounts of urine. Those affected were extremely thirsty, lost weight, and passed a tremendous amount of urine.
Q- How was diabetes first discovered?
Dr. Matthews: Probably through the observation that urine passed by a diabetic attracted flies (whereas normal urine does not). Early (and brave!) physicians tasted the urine of a diabetic and discovered that it was sweet. This remarkable insight was evident to the ancient Greeks, Chinese, Hindus, and many others. You're unlikely to see physicians these days who are that curious!
Q- What organs are affected in diabetes?
Diabetes mellitus- the passage of sweet urine- is a disease of the pancreas, an organ in the abdomen that secretes (among other things) insulin. Insulin tells the body to use glucose. Without insulin, the body cannot use carbohydrates, because carbohydrates are digested to glucose before they are used by the body.
When glucose builds up in the blood, it turns the blood into thin syrup, which draws water into the blood in the same way that salt will draw water out of food (the chemical process is called osmosis).
Q-Are there more than one type of diabetes?
Dr. Matthews- There are two types of diabetes mellitus- type 1 and type 2. Type 1 diabetes mellitus occurs because the pancreas stops making insulin (probably because of an immune attack much like rheumatoid arthritis). Type 2 diabetes is thought to occur when insulin doesn't work; the pancreas secretes plenty of insulin, (too much actually), but the body isn't able to use it. Researchers say that the insulin receptors are resistent, although when we finally fully understand this condition it will probably be much more complicated than that.
Q- So what was the connection between diabetes and headaches?
OK, we're getting to headaches now! So, in diabetes mellitus type 1 and 2, the blood sugar rises. Diabetics of both types have high blood sugars. Several years ago I noticed that extremely few patients suffering from headache also had diabetes and we have had over 30,000 outpatient evaluations in the Headache Clinic since we started in 1993.
In contrast, other major illnesses, such as stroke, heart disease, multiple sclerosis, and depression, seem to be more common in the Headache Clinic than the general population.
Why is this so striking? Because patients with chronic headaches tend to gain weight more than the general population, and in a heavier population diabetes type 2 should be more common than in the general population.
So, this is a real medical mystery. Migraine patients tend to gain weight; weight gain tends to cause diabetes type 2; but- and this is the kicker- diabetes type two protects against migraine!
Q- Have there been any scientific studies on this phenomenon?
Dr. Matthews: Yes, there has been one study (published in 2007 in Nature Clinical Practice Neurology ) which showed this protective effect of diabetes for headache. It was a large cross-sectional study.
Q- How do you think diabetes protects against headache?
Dr. Matthews: Let's turn that question inside out. Diabetes causes elevated blood sugar. OK, what about hypoglycemia, a condition of low blood sugar? If the high sugar of diabetes protects against headache, what about low blood sugar? People with symptoms associated with low blood sugar are much more likely to have headaches.
In fact, headache is one of the symptoms of hypoglycemia. Other symptoms include tremulousness, irritability, feeling faint, and dizziness which come on when you are hungry, along with headache. One of the most interesting treatments for stopping a migraine, reported by Ray Peat (an endocrine physiologist Ph.D. and researcher), is to quickly eat a quart of ice cream.
Q - So are some headaches caused by hypoglycemia?
Dr. Matthews: In the sense that some patients have headaches only when they miss meals, and curing the hypoglycemia cures the headaches. Many others will have hypoglycemic symptoms as one trigger for headache, along with other triggers (such as wine or certain foods, menses or other hormonal changes, fatigue or lack of sleep, or weather changes), so the word "cause" here is too strong. In these cases, both headaches and hypoglycemia are manifestations of a single deeper problem.
Q-What's the difference between hypoglycemia and just being hungry?
Dr. Matthews : Great question! Here's one way to think about it: if you have been on a low carb diet, or know someone who has, you know that you can feel hunger without feeling hypoglycemic (which is to say, jittery, tremors, or feeling faint). This happens because without carbohydrates, there is no need for insulin, so there is no need for buffering the stress of falling blood sugar with cortisol or adrenalin.
Carbohydrates cause insulin secretion, which lowers blood glucose, which leads to secretion of adrenalin, cortisol and glucagon to raise blood sugar back up again. Adrenalin is like amphetamine- it's a stimulant. Adrenalin directly causes contraction of skeletal muscles and blood vessels, which seems to trigger headache in some people. So it is possible to be hungry without secreting cortisol and adrenalin; you can be hungry without being jittery.
Q- What is the connection between insulin, headache, and depression?
Dr. Matthews: In addition to allowing glucose to be used up, which reduces the blood level of glucose, insulin also causes serotonin to rise in the brain; that is why many eat when they are sad. Headaches respond to eating, and sadness can also respond temporarily to eating for some people.
Q- How does blood sugar affect headache, depression, and hunger all at the same time?
Dr. Matthews: Another great question! If you were a student of mine today would get an "A+". Here's the basic answer: after you eat, digested food enters the blood as glucose (from carbohydrates), amino acids (from proteins), and fats. The pancreas secretes insulin to signal the body to take up and use or store glucose. Insulin also tells the body to take up the amino acids. The brain, however, only takes up a few amino acid types, not all of them. One of the amino acids the brain takes up is tryptophan. Within minutes, the brain takes tryptophan and makes serotonin, and serotonin makes you feel satisfied. This satisfied feeling produced by serotonin makes you feel good emotionally, and also makes you feel full.
By the way, serotonin is metabolized to melatonin, which makes you sleepy. That's why eating a large meal can make you feel full, happy, and sleepy. Remember last Thanksgiving?
Q- Besides eating regularly, is there anything you can do to prevent hypoglycemic headaches?
Dr. Matthews: Many people with hypoglycemia have relatively low cortisol, a hormone made by the adrenal gland to prepare the body for "fight or flight". Sometimes the adrenal hormones are relatively low in a patient who is under also chronic stress from headache pain. The body would ordinarily be putting out extra cortisol when in pain, but in headache patients with hypoglycemia cortisol is often rather low. Without enough cortisol, you have to secrete adrenalin after insulin to keep your blood glucose from falling too low. So a normal amount of cortisol will protect against headache by sparing the need for adrenalin.
Q-Are there any other symptoms that go along with hypoglycemia and headache?
Dr. Matthews: When I hear that a patient with headache also has hypoglycemic symptoms, I also ask about what I call postural fatigue. Are you the first person to want to sit down when you go out shopping at the mall with friends? If so, you have postural fatigue, and you may be lacking in cortisol. Both hypoglycemia and postural fatigue are symptoms of adrenal stress. The adrenals prepare you for stress by raising both blood pressure and blood glucose.
Q- What's the difference between postural fatigue and plain old feeling tired?
Dr. Matthews: With postural fatigue, you want to sit down before your friends do when you are at the mall. With the fatigue of depression, you don't want to go to the mall at all. With fatigue from other causes, you want to go to the mall, but you can't. Another similar condition, excessive daytime somnolence, refers to for example falling asleep any time you sit down, or at a traffic light. These distinct clinical conditions are likely to occur together. Another condition is weakness: you can't walk up stairs because your hips are weak, or or can't fix your hair because your arms are weak.
Cortisol is a "fight or flight" hormone. When present in adequate amounts, cortisol raises both blood glucose and blood pressure to prepare you for stress, including the stress of hypoglycemia. Without adequate levels of cortisol, you will use adrenalin to keep up your blood pressure and blood sugar to respond to stress- and adrenalin leads to being shaky, jittery, and dizzy, along with increased muscle and blood vessel changes leading to headache.
At the Headache Clinic we measure blood levels of these hormones in patients with headache who have hypoglycemic or postural fatigue symptoms. There are a number of simple and effective treatments for these conditions. What I like about these approaches is that we can get to a deeper level of treatment that will lead to better health, not just fewer headaches.
It's important to listen to what headaches are telling you about your body.
Q- Where can I go to find out more about headaches?
Dr. Matthews: You can go to our Web site at ncheadaches.com. There's a lot of information there, such as previous Health and Healing articles. You can also click through to the National Headache Foundation and the American Council on Headache Education, which we support as members. NHF is a family practice group, and ACHE is run by my specialty which is neurology.
Q- Who should be seen at the Headache Clinic?
Dr. Matthews: We recommend an evaluation at the Headache Clinic for any person who has persistent or severe headaches.