“I must admit that I stopped checking my blood sugar,” Dave said. “I used to stick myself and write the numbers in a book, but I had no idea what they meant. I’d eat the same thing and get different numbers. Finally, I just gave up.”
Sound familiar? Many people dutifully check their blood glucose levels but have no idea what the numbers mean. Part of the problem is that blood glucose levels constantly fluctuate and are influenced by many factors. The other part of the problem is that no two people are alike. A blood glucose reading of 158 mg/dl in two different people might have two different explanations.
Most people know that their bodies need glucose to fuel their activities and that certain foods or large quantities of almost any food will raise blood glucose. That’s the easy part. But just as cars require a complicated system of fuel pumps, ignition timing, batteries, pistons, and a zillion other things to convert gasoline into motion, our bodies rely on an intricate system to convert glucose into energy.
Back to basics
Insulin is a hormone secreted by the pancreas that helps regulate the way the body uses glucose. Its main job is to allow glucose in the blood to enter cells of the body where it can be used for energy. In people who don’t have diabetes, the pancreas changes how much insulin it releases depending on blood glucose levels. Eating a chocolate bar? The pancreas releases more insulin. Sleeping? The pancreas releases less insulin until the wee hours of the morning when the hormones secreted in the early morning naturally increase insulin resistance, so the pancreas needs to release a little more.
Insulin also controls how much glucose is produced and released from the liver. Glucose is stored in the liver in a form called glycogen. When blood glucose levels drop, the liver turns glycogen into glucose and sends glucose to the bloodstream. When there is enough glucose in the bloodstream, the pancreas signals the liver to stop sending glucose into the bloodstream. This system of signals and feedback loops keeps the delicate coordination of insulin release and blood glucose in balance.
In Type 1 diabetes, the coordination of insulin release and blood glucose is completely out of balance because the pancreas stops making insulin. Injected insulin is used to replace what is missing and supply insulin’s signals again.
With Type 2 diabetes, the pancreas makes insulin but not enough to keep up with the body’s demand. Studies have shown that Type 2 diabetes is progressive, meaning that the beta cells of the pancreas make less insulin over time. In addition, the cells of the body are unable to take glucose out of the bloodstream when needed because they resist the insulin that you need to allow glucose to enter cells. On top of that, the liver continues to send a lot of glucose into the bloodstream even when it isn’t needed because the signals telling the liver to shut off aren’t working. So there are three problems facing those with Type 2 diabetes: not enough insulin, insulin resistance, and a liver that won’t stop releasing glucose into the bloodstream.
Before any blood glucose reading has meaning, you need to know what you’re aiming for. Target goals for blood glucose set by the American Diabetes Association (ADA) are 70–130 mg/dl before a meal and less than 180 mg/dl two hours after the start of a meal. The American Association of Clinical Endocrinologists (AACE) has defined stricter blood glucose target goals of less than 110 mg/dl before a meal and less than 140 mg/dl two hours after the start of a meal. Ask your health-care provider whether you should use the ADA or the AACE targets as your goal. Both guidelines are based on evidence showing the blood glucose readings that are needed to prevent the complications of diabetes.