If you have diabetes, there’s a good chance you’ve heard about prediabetes. In fact, if you have Type 2 diabetes, you may have been told at some point in the past that you had prediabetes. Or perhaps you were told that you had impaired glucose tolerance or insulin resistance — and if you’ve struggled to understand what these terms mean, you’re not alone.
Prediabetes is a condition in which blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes. Some 35% of Americans over age 20, and more than 50% of those over age 65, currently have prediabetes. Prediabetes may also be called impaired fasting glucose or impaired glucose tolerance, depending on the type of blood test that was used to check a person’s blood glucose level. Some health-care providers may refer to prediabetes as borderline diabetes, but the American Diabetes Association prefers the term “prediabetes.” Studies show that people with prediabetes have an elevated risk of developing Type 2 diabetes within 10 years, especially if they make no changes to their diet or level of physical activity. (Click here to learn more about how prediabetes and Type 2 diabetes are diagnosed.)
However, if they do make healthful dietary changes, increase their level of daily physical activity, and lose some excess weight, many people with prediabetes do not develop full-blown diabetes. These same lifestyle changes can also help people who have Type 2 diabetes significantly lower their blood glucose levels and prevent long-term complications.
No one knows for sure why improved diet, increased exercise, and weight loss lower blood glucose levels and help prevent the progression of prediabetes to diabetes. But many scientists suspect that these lifestyle changes reduce insulin resistance, a condition that occurs when the cells in a person’s body (especially liver and muscle cells) lose some of their sensitivity to the action of insulin. With insulin resistance, more insulin is needed to keep blood glucose levels within normal limits. Over time, however, the pancreas may lose its ability to keep producing extra insulin, and blood glucose levels will rise.
Obesity, certain dietary habits, and lack of physical activity, along with genetic factors, increase a person’s risk of developing insulin resistance, prediabetes, and Type 2 diabetes. Individuals with Type 1 diabetes can also develop insulin resistance with weight gain and inactivity, resulting in a need for more injected or infused insulin. While you cannot change your genetic inheritance, you can reduce your level of insulin resistance through an active lifestyle, moderate weight loss if you’re overweight, and following a healthy diet.
How insulin works (or doesn’t)
Insulin is a hormone made in specialized cells of the pancreas called beta cells. Insulin is required to move glucose from your bloodstream into your body’s cells. Once glucose is in your cells, it is either used immediately for energy or put into storage for later use.
In Type 1 diabetes, the beta cells of the pancreas stop producing insulin, so insulin must be injected (or infused with a pump) to provide energy to cells and keep blood glucose levels within a desired range. Type 1 diabetes can develop very rapidly, often over a few months or even less time, and the condition cannot be reversed.