What Everyone Needs to Know About Prediabetes

Many people have heard about type 2 diabetes, but its common precursor, prediabetes, doesn’t get as much attention.

Prediabetes is estimated by CDC to affect 86 million Americans (51% of whom are 65 years and older), and an estimated 90% of people with prediabetes don’t even know it. According to the CDC, 15-30% of these individuals will develop type 2 diabetes within five years. In other words, as many as 26 million people that currently have prediabetes could develop type 2 diabetes by 2020, effectively doubling the number of people with type 2 diabetes in the US.

Prediabetes is also expensive. A 2014 Diabetes Care study estimated that prediabetes costs $44 billion annually, a 74% increase over a five-year period.

This learning curve provides an overview of prediabetes, outlining what it is, how it is diagnosed, how it is treated, and more. Prediabetes is an issue that affects our entire society and one that more and more people should be focused on.

Table of Contents

• What is prediabetes? 

• What are the symptoms of prediabetes?

• How is prediabetes diagnosed?

• Who is at risk of developing prediabetes?

• Why do people develop prediabetes?

• Is a prediabetes diagnosis serious?

• What can people with prediabetes do to avoid the progression from prediabetes to type 2 diabetes? 

• Can prediabetes be “cured”?

What is prediabetes?

Prediabetes is a condition where blood sugar levels are higher than normal, but not high enough to be diagnosed as type 2 diabetes. This occurs when the body has problems in processing glucose properly, and sugar starts to build up in the bloodstream instead of fueling cells in muscles and tissues. Insulin is the hormone that tells cells to take up glucose, and in prediabetes, people typically initially develop insulin resistance (where the body’s cells can’t respond to insulin as well), and over time (if no actions are taken to reverse the situation) the ability to produce sufficient insulin is reduced. People with prediabetes also commonly have high blood pressure as well as abnormal blood lipids (e.g. cholesterol). These often occur prior to the rise of blood glucose levels.

[To learn more about the basics of prediabetes, please see this short video created by ClearlyHealth and a downloadable resource on prediabetes created by the ADA.]

What are the symptoms of prediabetes?

People typically do not have symptoms of prediabetes, which is partially why up to 90% of people don’t know they have it. The ADA reports that some people with prediabetes may develop symptoms of type 2 diabetes, though even many people diagnosed with type 2 diabetes show little or no symptoms initially at diagnosis.

How is prediabetes diagnosed?

According to the American Diabetes Association, prediabetes can be diagnosed through one of the following tests:

1. A glycated hemoglobin test, also known as HbA1c or simply A1c, gives an idea of the body’s average blood sugar levels from the past two or three months. It is usually done with a small drop of blood from a fingerstick or as part of having blood taken in a doctor’s office, hospital, or laboratory.

2. A fasting plasma glucose (FPG) test measures a person’s blood glucose level after fasting (not eating) for eight hours – this is typically done in the morning. If a test shows positive for prediabetes, a second test should be taken on a different day to confirm the diagnosis.

Who is at risk of developing prediabetes?

A well-known paper published in the Lancet in 2010 recommends screening for type 2 diabetes (which would also screen for prediabetes) every 3-5 years in all adults over the age of 45, regardless of other risk factors. Overweight and obese adults (a BMI >25 kg/m²) are also at significantly greater risk for developing prediabetes, as well as people with a family history of type 2 diabetes.

According to the CDC, several other factors can have moderate influences on prediabetes risk in addition to age, weight, and family history:

• People with an African American, Hispanic/Latino, American Indian, Asian American, or Pacific Islander racial or ethnic background. The 2015 ADA Standards of Medical Care recommendations suggest Asian Americans with a BMI of 23 or above be screened for type 2 diabetes.  

• Women with a history of diabetes during pregnancy (“gestational diabetes”) or have given birth to a baby weighing nine pounds or more.

• People who are physically active fewer than three times a week.

The CDC offers a fast, online screening test for evaluating the risk for prediabetes. The ADA also offers a screening test to assess type 2 diabetes risk. Of course, these tests do not themselves confirm a prediabetes diagnosis, but just if someone may be at higher risk of developing it.

Why do people develop prediabetes?

Prediabetes develops through a combination of factors that are still being investigated. For sure, lifestyle factors (food, exercise, stress, sleep) play a role, but family history and genetics certainly do as well. It is easy to assume that prediabetes is the result of being overweight, but the relationship is not that simple. While obesity is one underlying cause of insulin resistance, many overweight individuals may never develop prediabetes or type 2 diabetes, and a minority of people with prediabetes have never been overweight. To make matters worse, it can be increasingly difficult to make healthy choices in today’s toxic food environment that steers all of us to make the wrong food choices, and there are many factors that can contribute to weight gain in addition to diet.

Is a prediabetes diagnosis serious?

There has been significant debate around the term ‘prediabetes,’ and whether it should be considered cause for alarm. On the one hand, it serves as a risk factor for type 2 diabetes and a host of other complications, including heart disease, and ultimately prediabetes implies that a degree of metabolic problems have started to occur in the body. On the other hand, it places a diagnosis on many people who may never develop type 2 diabetes. Again, according to the CDC, 15-30% of those with prediabetes will develop type 2 diabetes within five years. However, a 2012 Lancet article cites 5-10% of those with prediabetes each year will also revert back to healthy blood sugars.

What’s critical is not necessarily the cutoff itself, but where someone falls within the ranges listed above. The level of risk of developing type 2 diabetes is closely related to A1c or FPG at diagnosis. Those in the higher ranges (A1c closer to 6.4%, FPG closer to 125 mg/dl) are much more likely to progress to type 2 diabetes, whereas those at lower ranges (A1c closer to 5.7%, FPG closer to 100 mg/dl) are relatively more likely to revert back to normal glucose levels or stay within the prediabetes range. Age of diagnosis and the level of insulin production still occurring at diagnosis also impact the chances of reverting to normoglycemia (normal blood sugar levels).

What can people with prediabetes do to avoid the progression from prediabetes to type 2 diabetes?

The most important action people diagnosed with prediabetes can take is to focus on living a healthy lifestyle. This includes making healthy food choices, controlling portions, and increasing physical activity. Regarding weight control, research shows losing 5-7% (often about 10–20 lbs.) from your initial body weight and keeping off as much of that weight over time as possible is critical to lowering the risk of type 2 diabetes. This task is of course easier said than done, but sustained weight loss over time can be key to improving health and delaying or preventing the onset of type 2 diabetes.

Several prediabetes interventions exist based on evidence from the landmark Diabetes Prevention Program (DPP) study. The DPP study reported that moderate weight loss (5-7% of body weight, or ~10-15 lbs. for someone weighing 200 lbs.), counseling, and education on healthy eating and behavior reduced the risk of developing type 2 diabetes by 58%. Data presented at the ADA 2014 conference showed that after 15 years of follow-up of the DPP study groups, the results were still encouraging: 27% of those in the original lifestyle group had a significant reduction in type 2 diabetes progression compared to the control group.

If you or someone you know has been told they have prediabetes, here are a few helpful resources:

• In-person diabetes prevention programs: The CDC offers a one year long lifestyle change program through its National Diabetes Prevention Program (NDPP) at various locations throughout the US to help participants adopt healthy habits and prevent or delay progression to type 2 diabetes. This program is a major undertaking by the CDC to translate the findings from the DPP study into a real world setting, a significant effort indeed!

• Online diabetes prevention programs: The CDC has now given pending recognition status to three digital prevention programs: DPS Health, Noom Health, and Omada Health. These offer the same one year long educational curriculum as the DPP study, but in an online format. Some insurance companies and employers cover these programs, and you can find more information at the links above. These digital versions are excellent options for those who live far away from NDPP locations or who prefer the anonymity and convenience of doing the program online.

• Metformin: The DPP study found that metformin, the safest first-line therapy for type 2 diabetes, may help delay the onset of type 2 diabetes in people with prediabetes. Participants who took the low-cost generic drug had a 31% reduced risk of developing type 2 diabetes compared to the control group (those not on metformin or intensive lifestyle intervention). Again, 15-year follow up data showed that 17% of those on metformin continued to have a significant reduction in type 2 progression. At this time, metformin (or any other medication, for that matter) is not currently FDA approved for prediabetes, and it is sometimes prescribed “off-label” by a healthcare provider. Your healthcare provider can give you more information and determine whether metformin is a good option for you.

Can prediabetes be “cured”?

In the early stages of prediabetes (and type 2 diabetes), diligent attention to food choices and activity, and most importantly weight loss, can improve blood sugar numbers, effectively “reversing” the disease and reducing the odds of developing type 2 diabetes. However, some people may have underlying factors (such as family history and genetics) that put them at a greater risk of type 2 diabetes, meaning they will always require careful attention to blood sugar levels and lifestyle choices. Returning to old habits will likely put someone back on the road to prediabetes, and eventually, type 2 diabetes.

For more information about prediabetes, visit our resource page on type 2 diabetes and prediabetes, or our resource pages on diet, exercise, and health.