The Good News About Prediabetes

Health Writer
Medically Reviewed

Finding out that you have an increased risk for diabetes—a condition that is called prediabetes—may cause you to worry or panic.

Yet, a diagnosis of prediabetes can actually be good news, because you are in a position to initiate lifestyle changes (and take medication, if necessary) that can help delay the onset of diabetes or even ward it off altogether.

According to landmark research, proven steps that prevent diabetes have particularly dramatic benefits in people over 65, half of whom have prediabetes.

What’s more, new policies mean that Medicare will cover the costs of programs focused on lifestyle improvement that are able to help people prevent diabetes.

What is prediabetes?

You don’t develop type 2 diabetes overnight. Doctors have discovered that most people who are diagnosed with the disease first pass through a phase when their blood glucose levels are higher than normal, but not elevated enough to warrant a diagnosis of type 2 diabetes.

A physician may use any one of several common blood tests to measure blood glucose levels. According to the American Diabetes Association (ADA), you have prediabetes if results from one of these tests fall into a given range:

Hemoglobin A1c, which marks the impact of high blood sugar on red blood cells in your circulation: 5.7 percent to 6.4 percent

Fasting blood glucose: 100 mg/dL to 125 mg/dL

Oral glucose tolerance test, in which you drink a beverage containing a standard concentration of glucose and subsequently undergo a series of blood glucose measurements over the next 2 hours: a value anywhere between 140 mg/dL and 199 mg/dL within 2 hours of consuming the beverage.

Variations in criteria

Other medical associations have different definitions of prediabetes. The World Health Organization (WHO) uses the same the same oral glucose cutoff as the ADA but recommends a higher fasting glucose threshold of 110 to 125 mg/dL. The International Expert Committee's (IEC) A1C level cutoff is 6.0 to 6.4 percent.

"The cutoff points for prediabetes came from studies involving two large groups of people and are open to interpretation, thus leading to significant debate and a lack of consensus," says John E. Swartzberg, M.D., a clinical professor emeritus at The University of California, Berkeley School of Public Health.

"For example, hemoglobin A1C concentrations are often higher in African-Americans than in whites. Applying the same thresholds from one group of people to all demographic groups can be misleading."

With the lower cutoff value, more people will be classified as having diabetes. The criteria used for establishing a diagnosis determines the percentage of adult Americans considered to have diabetes. This figure varies significantly, from 12 percent to more than 30 percent.

The risk of type 2

About 86 million Americans have prediabetes; more than two-thirds of them will eventually develop type 2 diabetes. Other factors increase the risk, such as obesity and having a close relative (such as a parent or sibling) who had the disease. But having prediabetes raises your risk even more.

Prediabetes doesn’t cause well-defined symptoms, and many people aren’t aware they have the condition. The only way to find out if you have rising blood glucose that puts you at risk for type 2 diabetes is to see your doctor on a regular basis.

If you are diagnosed with prediabetes, ask your doctor about the National Diabetes Prevention Program, which helps people at risk for diabetes make lifestyle changes proven to lower the risk.

Some employers and insurers cover the cost of the program, and in 2016, Medicare announced that it would soon begin paying for care aimed at preventing diabetes, too.

The power of change

An important 2002 study proved that people with prediabetes can forestall and even prevent type 2 diabetes by making simple lifestyle changes. The study, known as the Diabetes Prevention Program (DPP), included 3,234 people with prediabetes.

The typical subject was 51 and obese. Participants in one group were encouraged to lose 7 percent of their body weight. Toward that goal, they were asked to eat a low-calorie, low-fat diet and engage in some form of exercise, such as brisk walking, for at least 150 minutes per week.

A second group was not asked to change their diets or exercise more, but was instead treated with a commonly prescribed glucose-lowering drug, metformin. A third group was given placebo pills.

Three years later, the researchers found that subjects who took metformin were 31 percent less likely to develop diabetes than those given placebos. However, diet and exercise conferred far greater protection, lowering the risk for type 2 diabetes by 58 percent.

In an intriguing subplot to this story, the study also found that people aged 60 and older who ate healthier diets and exercised more got the most disease protection of all, lowering their risk for type 2 diabetes by 71 percent.

The researchers who conducted the DPP have continued following many of the original study participants. A decade after the study began, they found that people in the diet-and-exercise group still had the lowest rates of type 2 diabetes, with the greatest impact occurring in older men and women.

For participants who were 60 or older at the study’s onset, lifestyle changes lowered the risk for type 2 diabetes by 49 percent, while taking metformin had no effect.

After 15 years, diet and exercise remained the most effective protection against diabetes, according to a 2015 study in the Journal of Endocrinological Metabolism; it also showed that people over 60 in the lifestyle-changes group had a 23 percent lower risk for diabetes complications such as nerve or kidney damage compared with men and women in the metformin group.

More about diet and exercise

Since publication of the DPP’s original findings in The New England Journal of Medicine, other researchers have revealed more clues about how diet and exercise can help prevent type 2 diabetes.

A four-year study published in Annals of Internal Medicine in 2014 found that people who ate a Mediterranean-style diet were 40 percent less likely to develop diabetes than others who were simply advised to cut back on fat.

A Mediterranean-style diet includes cooking with extra virgin olive oil, consuming plenty of vegetables, fruits, legumes (such as beans), and fish, while avoiding red meat, processed foods, and sweets.

Based on this study and others like it, many researchers feel that diets such as the Mediterranean diet are ideal components of a sound diabetes prevention strategy.

Other research suggests that diversifying your workout may give you an added safeguard if you have prediabetes.

Scientists at The Harvard School of Public Health examined the exercise habits of more than 32,000 male health professionals who were participating in a long-term study. They found that men who exercised at least 150 minutes per week, as the DPP dictated, lowered their risk for developing type 2 diabetes, whether they performed aerobic exercise or weight training.

However, men who performed both aerobic exercise and weight training gained the most protection, lowering their risk by 59 percent. A physical therapist or licensed trainer can help you devise an appropriate strength-training program.

A limited role for medication

While the value of lifestyle changes for delaying or preventing type 2 diabetes is clear, some people with prediabetes may benefit from medication.

The ADA suggests that doctors may consider prescribing metformin for anyone with prediabetes, but especially women who have had gestational diabetes, as well as people under 60 who have a body mass index (BMI) over 35. Metformin and lifestyle modification can be combined to provide the benefits of both interventions if needed.

Learn more about the risks associated with diabetes, including falls and Alzheimer's.