Qs people asked me on science and my replies to them - Part 185

Q: Why do I get headaches while fasting? I don't have diabetes.

Krishna: Low blood sugar levels. 

Hypoglycemia is a condition caused by not having enough sugar in the bloodstream. Hypoglycemia occurs when your blood sugar levels dip below 70 mg/dL. This can happen after skipping a meal or going a long period of time without eating.

You may also experience reactive hypoglycemia. This is a rapid drop in your blood sugar after eating a meal. This occurs within four hours of eating. An example of reactive hypoglycemia is when you eat simple sugars, such as white sugar. This raises blood sugar fast and then insulin overproduces, causing a rapid decline in blood sugar. 

Both types of hypoglycemia can result in headaches and migraines. This can happen even without diabetes.

But if you have diabetes you may experience hypoglycemia frequently, as the body cannot control blood sugar levels on its own. This may be exacerbated if you’re taking prescribed insulin.

Low blood sugar may cause a general headache or even a migraine. A headache may be dull in nature and throb around your temples. You may also feel nausea with a headache or migraine caused by hypoglycemia. This is a serious condition, as glucose is the primary source of fuel for many cells in the body, including those in the brain.

Other symptoms of hypoglycemia include: lightheadedness, weakness, sweating, sleepiness, shakiness, pale skin, heart palpitations, hunger, anxiety, mood changes, double vision or blurred vision, confusion and change in consciousness (if low blood sugar is severe). 

A headache can also indicate that blood sugar levels are too high, which doctors call hyperglycemia. Alternatively, blood sugar levels may be too low, which doctors call hypoglycemia. 

The higher the fluctuations in blood glucose levels, the more likely it is that a person with diabetes will experience headaches.

Headaches a person can link to these fluctuations might be a result of changing levels of hormones, such as epinephrine and norepinephrine. These hormones may constrict the blood vessels in the brain and cause discomfort.

The first step in treating a hypoglycemia-induced headache is to confirm that the pain is occurring due to low blood glucose. A blood glucose test can verify this issue.

Taking a blood glucose test is especially important for people with diabetes who wake up with a headache in the morning, as it can be a sign of nocturnal hypoglycemia.

Broadly,  headaches can be classified as either primary or secondary: