I just had a frightening experience. A severe hypoglycemic, I took my regular 5 units of R Humulin 30 minutes before lunch. Instead of my normal sandwich and milk at lunch, I drank a glass of Slim Fast with milk. I carefully read the label and figured out that it was almost identical to the sandwich in calories, carbs and sugars.

Later that afternoon I laid down for a nap and, after a couple of hours, my wife was unable to wake me. She knew it was a low, but was unable to force anything down me, as I was virtually comatose. The paramedics arrived shortly and measured my blood sugar at 22 mg/dl. They are not allowed to give an injection, so they could not administer Glucagon, but rushed me to a nearby hospital where they started me on an IV of glucose. Even then, it was over an hour before they could wake me.

I am a constant reader of your magazine and have never read anything that would have warned me of such an experience. My doctor thinks that Slim Fast acted very rapidly, and was gone before the insulin wore off—leaving me extremely low.

I write this as a warning to others who might not know to consider the rapidity of absorption of sugars. I am 69 years old and have been a type 1 for 30 years.

John Hooper
Coronado, California

Editor's Note: We asked nutritionist Marion Franz, MS, RD, CDE, to comment on this reader's experience.

Your letter raises some very interesting questions. There could be several factors that may have contributed to your severe hypoglycemic episode. Although there are some differences in how rapidly blood glucose levels increase after consuming different foods or beverages, the peak responses tend to be within minutes regardless of the carbohydrate eaten.

However, the duration of the glucose response also differs and may well have been less for your lunch of Slim Fast versus your usual lunch. Therefore, the peak insulin response from your Regular insulin would occur as your blood-glucose levels were dropping. This is one of the main advantages of using rapid-acting insulin, such as lispro or aspart, in place of Regular insulin. The peak insulin response correlates better with the peak glucose response and it can be taken immediately before eating.

However, other factors may have contributed to the hypoglycemia. Did you do any additional physical activity that morning? Hypoglycemia is more likely to occur after exercise than during, and especially after exercise that is sporadic. Have you had frequent episodes of hypoglycemia? People who have frequent episodes of hypoglycemia are also more susceptible to hypoglycemia in the future. You may have heard "hypoglycemia begets hypoglycemia." Individuals need to make adjustments in their insulin regimens and glucose goals to try and reduce the frequency of hypoglycemia.

It may also be that the carbohydrate content of the Slim Fast lunch was less than your usual lunch. However, even if it were less you would not expect such a severe hypoglycemic event from the difference. Of course, there is always the possibility of taking the wrong insulin dose as well. However, it sounds from your letter as if it is more likely that there was not enough glucose from the carbohydrate you ate when the Regular insulin was at its peak activity.

As you well know, it is often frustrating trying to determine exactly what is the cause of hypoglycemia (and hyperglycemia) in persons who take insulin. Good luck in the future and check with your doctor in regard to changing your insulin regimen.

Marion Franz, MS, RD, CDE
Nutrition Concepts by Franz, Inc.
Minneapolis, Minnesota