Prediabetes is a precursor condition to type 2 diabetes, characterized by higher-than-normal blood glucose levels and insulin resistance. It’s also called impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), depending upon the test used to diagnose it. The U.S. Centers for Disease Control and Prevention (CDC) and the American Diabetes Association (ADA) estimate that 86 million Americans aged twenty years or older are living with prediabetes, and roughly 90 percent remain unaware of their condition. Without intervention and appropriate treatment, people with prediabetes are at risk for developing type 2 diabetes within ten years.
With early intervention and lifestyle adjustments, prediabetes can be slowed, stopped, and even reversed.
Prediabetes Risk Factors
Prediabetes risks factors are the same as those for type 2 diabetes. They include:
- Being overweight or obese (i.e., a BMI of 25 or higher)
- First-degree family history of diabetes
- Being age forty-five or older
- Sedentary lifestyle
- Low HDL cholesterol (35 mg/dl; 0.90 mmol/L) and high triglycerides (250 mg/dL; 2.82 mmol/L)
- High blood pressure (consistent reading of 140/90 mmHg or higher)
- History of gestational diabetes, or gave birth to a baby weighing more than nine pounds
- Belonging to one of the following ethnic populations: African American, Native American, Latino, Asian American, Pacific Islander
- Having polycystic ovary syndrome (PCOS)
- A history of vascular disease
The American Diabetes Association (ADA) uses screening recommendations for prediabetes that are based upon the current guidelines for type 2 diabetes screening. Testing is recommended for men and women forty-five years of age and older, regardless of risk factors or symptoms, every three years. Individuals younger than forty-five should also be screened if they have a BMI of 25 or more and additional risk factors (as listed above).
Prediabetes is diagnosed with one of two blood tests: a fasting plasma glucose test, or a two-hour oral glucose tolerance test (OGTT). The fasting plasma glucose test requires an eight-hour fast (no food or drink except water), after which a blood draw is performed. It is usually done in the morning. For an oral glucose tolerance test, a patient is given a drink containing 75 grams of glucose, and a blood draw is taken two hours later.
The following lab values are the American Diabetes Association (ADA) practice guidelines for the diagnosis of prediabetes:
- A fasting plasma glucose value between 100 and 125 mg/dL (5.56-6.94 mmol/L) or more (indicating impaired fasting glucose).
- An oral glucose tolerance test plasma glucose value between 140 to 199 mg/dL (7.78-11.06 mmol/L) at two hours post-glucose load (indicating impaired glucose tolerance).
- An A1C range of 5.7-6.4 percent.
If testing is positive for prediabetes, a follow-up test should be performed on a subsequent day to confirm the diagnosis. People with diagnosed prediabetes should receive regular retesting every one to two years to monitor for type 2 diabetes. Individuals with a normal screening result can be retested every three years.
The recommended treatment for prediabetes is similar to the prevention strategies for type 2 diabetes. In many cases, the progression of prediabetes can be halted, and even reversed, by making healthy eating and fitness habits a daily routine.
The Diabetes Prevention Program (DPP), a large-scale study of diabetes prevention strategies in those at high risk for type 2 diabetes (including those with impaired glucose tolerance), found that even moderate lifestyle changes can make a big difference in preventing diabetes and reversing prediabetes in some people. DPP participants who engaged in thirty minutes of physical activity daily and lost 5 to 7 percent of their body weight cut their risk of type 2 diabetes by 58 percent.
If you have prediabetes, losing excess pounds through proper diet and exercise can improve the body’s ability to use insulin and process glucose more efficiently. A registered dietitian, or RD, can help you develop a food plan that works for you. Always check with your physician before starting a new fitness program, especially if you have a chronic illness or other health problems.
The DPP also found that taking diabetes medication was beneficial to some individuals with prediabetes/impaired glucose tolerance. Study subjects treated with Metformin reduced their risk of type 2 diabetes by 31 percent. The ADA recommends consideration of Metformin therapy for individuals with prediabetes, especially those with a BMI greater than 35, those younger than sixty years old, and women with prior gestational diabetes.
Updated by Julia Telfer, MPH, 10/16.