Reactive Hypoglycemia: a cautionary tale

For many people, losing a lot of weight results in blood glucose (BG) levels at or close to normal, and your doctor may tell you that you're no longer diabetic. If this happens to you, first of all you should be congratulated for the difficult job of losing weight. That's wonderful.

But you should also be vigilant to make sure you don't get reactive hypoglycemia, which means very low BG levels after you've eaten a lot of carbohydrate. This can happen even when you're not diabetic.

I had reactive hypoglycemia about 20 years before I got the diabetes diagnosis. At the time, I was a night owl and hated getting up early in the morning. But occasionally, at the daily newspaper where I worked, I had to do the "wire desk," which meant arriving at 7 am. Because I hated it so much, I'd treat myself to a chocolate doughnut. Usually I didn't eat breakfast at all.

Then at almost exactly 4 hours after the doughnut and black coffee, I'd get the shakes and feel as if I'd die if I didn't eat something. In fact, I could almost set my watch by this phenomenon. "Oh. The shakes. It must be 11 o'clock." Then I'd eat a candy bar and feel fine for the rest of the day.

Why does this happen?

Insulin secretion is biphasic. When a nondiabetic eats a carbohydrate food, the pancreas quickly spurts out a pulse of insulin. This pulse doesn't last very long but it's enough to keep the  carbohydrate that reaches the intestine from going very high. It also suppresses the production and release of glucose from the liver. This is called the phase 1 or first phase insulin response.

Then insulin is secreted continuously as long as carbohydrate comes into the system in proportion to the amount of carbohydrate reaching the intestine. This is the phase 2 or second phase insulin response, and it lasts much longer than the first one.

The food that we eat, including carbohydrate, isn't dumped into the intestine all at once. Instead, the stomach releases only a certain amount at a time, usually containing about the same number of calories, so the insulin release is pretty steady. Liquids leave the stomach faster than solids.

Unfortunately, those of us with type 2 diabetes tend to lack a first phase insulin response and may have lacked it for a long time before we were diagnosed with diabetes. This means that when we eat carbohydrate, our BGs aren't knocked down by that first insulin pulse, so they go much higher than they would in a nondiabetic who ate the same amount of carbohydrate. Then the body sees these high numbers and assumes they're that high despite a first phase insulin response. So the second phase response is extra strong, and with all that extra insulin, we may go low. Some people call this "too much too late."

Now, no one really knows at what point in our life the first phase insulin response is eliminated, although there is evidence that first-degree relatives of people with diabetes have impaired first-phase insulin responses despite having normal BG levels.  We also don't know if or when the first phase is restored when people normalize BGs enough to be considered nondiabetic again.

I was in a clinical study in which they did an intravenous glucose tolerance test that measured both BG and insulin after a huge dose of glucose. I started with almost no phase 1 response. But after I was on the study drug (salsalate) for a couple of weeks, the phase 1 response was restored to about 70% of normal, which is consistent with the idea that the situation is reversible.

Weight loss alone may or may not restore the phase 1 response, but there's some evidence that phase 1 is restored after weight-loss surgery.

So if you've reversed your diabetes so that your BG levels are in normal ranges, you may still lack that phase 1 response and be sensitive enough to large carbohydrate loads that you'll have reactive hypoglycemia.

That happened to Joseph recently. He had lost a lot of weight after gastric bypass surgery, and his BG levels were usually normal, but he still watched his diet and didn't go overboard with the starches. Then one day he was at a football game, and it was very cold and his friends had a lot of tasty crackers with them, so he ate some. No, he ate a lot. A few hours later, he felt odd and tested his BG. It was 35. Luckily, he wasn't alone, and someone gave him some juice and he recovered.

I have no idea how low I was when I worked the wire desk and got the shakes after eating a doughnut with black coffee. But I do know it was very unpleasant. So if you're a recovered diabetic, be vigilant and don't let this happen to you. Avoid carbohydrate fests, especially on an empty stomach. And if you can't avoid them, make sure you have available some glucose tablets or other food that will raise BG quickly in case you do go low.

Reactive hypoglycemia is counterintuitive ("How could I be low when I just ate all those carbs?"), but it can be serious. You can outsmart it, though, if you're prepared.

.