Prediabetes / Diabetes Screening Test
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What is Prediabetes? Symptoms, Treatment & Prevention

Medically reviewed by

Ford Brewer, M.D.


Prediabetes / Diabetes Screening Test

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Key takeaways

Prediabetes is characterized by elevated blood sugar. Patients’ blood sugar may be higher than normal, yet not high enough to meet the standard of Type 2 Diabetes.

Prediabetes is sometimes referred to as “impaired fasting glucose” (IFG) or “impaired glucose tolerance” (IGT).


Every year, over 200,000 Americans receive a tough diagnosis of Diabetes.

This condition used to be known as “Adult-Onset Diabetes” to distinguish it from the related disease; ‘Type 1 Diabetes’, a pancreatic autoimmune disorder some children already have at birth. “Adult-Onset Diabetes” is now a misnomer, since the deteriorating quality of the American diet has led to an epidemic of type 2 diabetes diagnoses among minors too.

In normal bodies, the pancreas produces insulin, a hormone that helps transfer the simple sugar glucose from the blood to muscles, liver, and fat cells. Those cells can then process glucose as energy.

The various forms of diabetes cause the body to become insulin-resistant or insulin-impaired, either by not producing insulin or failing to use it effectively. As a result, glucose never makes it to the cells that need it - starving the cells. This leaves insulin trapped and not utilized in the blood. As the body becomes insulin-resistant, patients experience elevated blood sugar and an increased risk of heart disease, stroke, blindness, and kidney failure.

A diagnosis of Type 2 Diabetes correlates with an average loss of ten years of the patient’s lifespan.

Less well-known, however, is the matter of almost 40% of American adults who are prediabetic. According to the CDC, 90% of people living with this condition don’t even know they have it, or that it represents an urgent window of opportunity to avert Type 2 Diabetes.

Patients with prediabetes exhibit early symptoms of insufficient insulin use within the body. As a result, blood glucose levels begin to rise.

Prediabetes is a significant risk factor for the development of T2D. Whether these prediabetics know they have it or not, most patients diagnosed with T2D do present with prediabetes first.

A CDC study published in JAMA pediatrics revealed a higher prevalence of prediabetes in males vs. females. In a study of 5,800 patients:

  • 22.5% of adolescent boys had prediabetes, compared to 13.4% of adolescent girls
  • 29.1% of young adult males had prediabetes, compared to 8.8% of young adult females.

Prediabetes Risk Factors and Causes

Despite its stealthy nature, prediabetes has a number of well-known risk factors.

Obese or overweight people are likely to be prediabetic, especially people with pronounced belly fat, and body fat in general. Excess fat cells make the body more resistant to insulin. A waist measurement over 40” in a man, or 35” in a woman, correlates strongly with prediabetes, as does a body mass index (BMI) over 25.

A history of gestational diabetes is another risk factor. This type of diabetes occurs in pregnant women when pregnancy changes in the body impede insulin uptake and result in high blood sugar. Gestational diabetes can also affect the baby’s health.

Other risk factors include:

  • Having given birth to a baby over nine pounds in birth weight
  • A lifestyle including little or no exercise
  • Latino, Native American, African American, or Pacific Islander heritage
  • Aged 45 or older
  • High LDL cholesterol
  • Low HDL cholesterol
  • High triglycerides
  • A diet high in sugars, sugary drinks, red meat and/or processed meats
  • A diet low in whole grains, vegetables, fruits, nuts, and unsaturated fats
  • Sleep apnea or other sleep disorders
  • Constant or occasional night shifts

You should definitely get tested for prediabetes if you:

  • Have heart disease
  • Exhibit abnormal blood sugar readings

How to Screen for Prediabetes

Prediabetes can be detected by a blood test. Indicators of prediabetes revealed by examining the blood, and often increase with age, include:

Elevated Hemoglobin A1c

Also known as Glycated Hemoglobin or HbA1c. Hemoglobins are proteins found in the red blood cells that carry iron. A1c is specifically linked to sugars, and is an important part of diabetes testing. According to the American Diabetes Association, HbA1c is still used less frequently than glucose for screening, but is more likely to result in a clinical diagnosis.

  • A blood percentage of 4%-5.6% HbA1c is considered normal.
  • A blood percentage of 6.5% HbA1c is often considered diabetic.
  • A blood percentage of 5.7%-6.4% HbA1c could be considered prediabetic.

HbA1c is quick to test for and requires no fasting before lab appointments. However, some physicians warn that comparing hemoglobin between populations can be different (ex. Genetic differences, anemia, pregnancy, etc.), and thus HbA1c shouldn’t be the definitive diagnosis for prediabetes. 

Elevated Fasting Plasma Glucose Levels

When we talk about “high blood sugar,” we mean the simple sugar glucose and its prevalence in the plasma, the liquid component of blood in which blood cells are suspended.

  • Healthy fasting plasma glucose (FPG) levels will fall below 100 mg/dL.
  • FPG above 126 mg/dL indicates diabetes.
  • Any FPG result between 100 and 126 mg/dL does not meet the clinical definition of diabetes but could indicate prediabetes.

As the name indicates, this lab test requires patients to fast before their lab appointment.

Glucose Tolerance Tests

An Elevated Fasting Plasma Glucose Levels screening may be paired with a glucose tolerance test to determine if the patient is impaired in his/her ability to absorb glucose.

The most common test is the two-hour 75-gram oral glucose tolerance test (OGTT).

After the fasting blood sample is obtained, the patient is then instructed to drink a solution consisting of 75 grams of glucose dissolved in water. Two hours after drinking the glucose solution, another blood sample is taken.

  • If, after two hours, Fasting Plasma Glucose has risen to a range below 140 mg/dL, this indicates a normal uptake of glucose - although 120 is optimal.
  • If FPG has risen above 200 mg/dL, this level is consistent with a diagnosis of diabetes.
  • An FPG range between 120 and 200 mg/dL after the OGTT can indicate prediabetes —an impairment of glucose uptake, but not severe enough to diagnose diabetes yet.

At-Home Blood Tests For Prediabetes

Medicine has adapted to the digital age to bring health screening tools directly into the hands of consumers. This includes home blood screening options like imaware™. The imaware™ home screening kit for prediabetes allows patients to collect their own blood samples quickly, safely, and painlessly.

They then submit the samples to confidential labs and receive results by a secure online portal. imaware™ allows patients to check their HbA1c and Glucose levels to discover if they fall within prediabetic ranges, without making a clinic or lab appointment.

What are the Symptoms of Prediabetes?

Prediabetes goes undiagnosed so often because it often has no obvious symptoms—at least, nothing to cause immediate alarm.

If checked, patients might present with:

  • Higher-than-normal systolic blood pressure
  • Higher-than-normal non-HDL cholesterol
  • Low insulin sensitivity or glucose tolerance.

All of these internal indicators might go completely unnoticed if not tested for.

Particularly sensitive individuals might notice:

  • Excessive thirst
  • Excessive urination
  • Blurry vision
  • Fatigue
  • Difficulty healing from cuts or sores

Associated Conditions with Diabetes

Associated conditions might indicate prediabetic status, even if the ensuing symptoms are related to the associated condition and not to prediabetes. Examples include:

Acanthosis Nigricans

This associated condition manifests as dark, velvety patches of skin, typically grouped around the elbows, knees, armpits, knuckles, and neck. Acanthosis nigricans is associated with insulin resistance.

Polycystic Ovarian Syndrome

Another condition associated with insulin resistance, polycystic ovarian syndrome (PCOS) affects post-pubescent women characterized by an excess of the male hormone androgen and enlarged ovaries surrounded by follicles. These follicles inhibit the release of eggs.

PCOS is also characterized by long menstrual cycles with infrequent periods. While acne can appear for many reasons, if a patient has never had it before and it suddenly shows up, especially in later life, it’s worth discussing PCOS (and the possibility of prediabetes) with a doctor.

What are the Prediabetes Blood Sugar Numbers?

Prediabetes is characterized by the following blood sugar metrics:

  • Fasting plasma glucose (FPG) between 100 and 125 mg/dL.
  • After a 75mg 2-Hour Oral Glucose Tolerance Test, FPG levels of between 120 and 200 mg/dL.
  • Glycated hemoglobin (hemoglobin A1c or HbA1c) between 5.7% and 6.4%. Note that pregnant women or persons with a hemoglobin variant may return inaccurate results on an HbA1c test.

These ranges apply to both adults and children.

How to Reverse Prediabetes

Not everyone who meets the definition of prediabetes will progress to Type 2 Diabetes. However, many patients diagnosed with T2D have probably been prediabetic for years or decades without even knowing it. It is a strong correlative and significant risk factor.

Prediabetic blood sugar and hemoglobin test results should serve as a call to arms. Patients have a rare opportunity to reverse this damaging course and protect themselves from a debilitating, extremely life-shortening condition that brings a plethora of complications. Many diabetics have retinopathy or neuropathy by the time they receive a diagnosis of T2D, and this can be avoided by paying attention to these biomarkers and making lifestyle changes in advance. 

Many prediabetics are overweight or obese. A reduction of body weight (especially body fat) by 5%-7% (usually losing 10-20 pounds) strongly correlates with a reversal of prediabetic blood sugar levels.

The best way to reverse prediabetes is to adopt a healthy lifestyle, including:

Track and Maintain Blood Glucose

Continuous Glucose Monitoring (CGM) is key to maintaining a healthy blood sugar level. A glucose monitor can be obtained through a physician. The Freestyle Libre and Dexcom 6 are the most popular methods for tracking your blood sugar 24 hours a day, 7 days a week. Failure to maintain a proper blood glucose level is like driving on the highway with no speedometer. 

Most of Dr Brewer’s patients, even those with full Type 2 Diabetes, maintain their blood sugar within healthy levels using wise dietary choices. Jenny Ruhl, in her book Blood Sugar 101, coined the term, “Eat to the glucometer.” It’s one of the most powerful keys to prediabetes prevention and reversal. Maintaining a healthy weight and body fat level are the other keys to health. 


Building more physical activity into your daily routine can contribute significantly to the reversal of prediabetes. Physical activity lowers blood glucose levels and reduces body weight.

Thirty minutes of exercise a day, five days a week, is a proactive approach to reversing prediabetes. If this is too much right off the bat, consider starting slowly and building up exercise as a habit before increasing the intensity. Activities to consider include jogging, walking, swimming, cycling, weight training, and yoga. Make sure to check with your doctor before commencing an exercise routine.

Healthy Food Choices

Prediabetics don’t necessarily need to eat less food if they can transition to higher-quality foods, with a slower carb content.

  • Someone with prediabetes can eat as much as they like of non-starchy vegetables like carrots, broccoli, green beans, spinach, and other leafy greens, or at least three servings per day.
  • Fruit, on the other hand, contains a lot of sugar. Try to limit servings of fruit to between one and three, including lower fructose fruits like raspberries, blackberries and strawberries. Fruit can be an appropriate substitute for high-fat or high-sugar snacks like chips or candy, however, as long as intake is limited. Other good snack choices include seeds, nuts, and whole-grain crackers.
  • While many health experts advise eating whole grains, sprouted grains, and brown rice as a substitute for enriched, white grains, they are also high in glycemic value, and should be consumed sparingly. 
  • Vegetables, fruits, and whole grains are excellent sources of fiber, helping to balance the appetite and control cravings for high-calorie, high-fat foods.
  • Limit the amount of red or fatty meats, while emphasizing lean meats like chicken, or meats rich in good fatty acids such as fish or other seafood.
  • Avoid fatty milk and cheeses. Skimmed milk and low-fat cheeses are acceptable.
  • Avoid sugary drinks like soda, fruit juices, sweetened coffee or tea, or sugary sports drinks like Gatorade as much as possible.

Not every food recommendation is appropriate for every person, as body chemistry is quite individual. Consider consulting a nutritionist for more personalized recommendations.


Lack of sleep makes it nearly impossible to lose weight. When the body loses sleep, it responds with overproduction of the hormones leptin and ghrelin. These hormones make you hungry.

Losing sleep also reduces your body’s ability to use insulin effectively, resulting in elevated blood sugar. It can be a vicious cycle, too, because excessive body weight also puts you at risk of sleep disorders like insomnia and sleep apnea.

Certain behavioral habits can help normalize the sleep cycle, even for overweight persons. These habits include:

  • Setting a schedule. Go to bed and wake up at the same time every day to establish a stable circadian rhythm (24-hour physiological cycle)
  • Relaxing before bed. Try lying down and reading an hour before bedtime
  • Avoid caffeine after lunchtime. If you consume caffeinated coffee, tea, or other products, restrict consumption to the morning
  • Turning off all screens. Don’t watch TV, look at your smartphone, or look at your computer screen a full hour before bedtime
  • Sleep in a darkened room. Make sure no lights are on in your sleeping room, including indicator lights on devices. Consider blackout blinds if you live on a lighted street
  • Set the proper temperature for your sleeping room. Between 60 and 67 degrees Fahrenheit is optimal for the sleep cycle. Let in some fresh air if you tend to sleep restlessly in a warmer room.

Other Resources

Many diabetes-prevention resources, both in-person and online, could help patients with prediabetes. The Center for Disease Control (CDC) operates the National Diabetes Prevention Program (NDPP) throughout the US, offering year-long, in-person lifestyle change programs. DPS Health, Noom Health, and Omanda Health also offer year-long lifestyle change programs via their industry-leading online platforms.

Prediabetics should make regular doctor visits, every three to six months at least, to track their progress. For more information on getting help with prediabetes, read our guide to reversing prediabetes.

Please consult with your physician to see if there is a medication that might be right for you. 

What to Do if You Think You Have Prediabetes

If you suspect that you may be prediabetic, take immediate steps to safeguard your health. Type 2 Diabetes is a serious condition, and prediabetes a priceless window of opportunity to nip it in the bud.

1. Get tested to verify

imaware™ offers a do-it-yourself home blood testing kits that screens for prediabetes indicators, including Hemoglobin A1c and fasting plasma glucose levels.

You can submit your test confidentially to a CLIA certified lab and receive your results by a secure online portal. It’s the easiest, most affordable, and most convenient way to confirm if your blood sugar metrics are rising to prediabetic levels.

2. Be proactive—make lifestyle changes

Don’t wait for a diagnosis of diabetes or prediabetes to make changes. As of 2019, 76% of Americans do not get enough exercise. Most Americans also eat too much sugar, fat, and sodium, while eating too few vegetables, fruits, and unsaturated fats.

Take steps now to join the minority with healthy habits. Add exercise, a healthy sleep cycle, and healthy eating choices to your routine. Become educated about the science of fitness, nutrition, and weight loss. 

A reduction of 5-7% pounds of body weight often correlates with a reversal of prediabetes. If you’re unsure how to calculate it, take your total body weight and divide it into 20, for the minimum desired loss to aim for. Especially keep an eye on dangerous excess abdominal fat.

Make a meal plan and an exercise plan. Feel free to start slow—a light walk every other day, or cutting out sugary beverages. If you try to do too much exercise too soon or completely overhaul your diet, you run the risk of burning yourself out. Focus instead on the gradual adoption of manageable, sustainable habits.

If necessary, consult a personal trainer, nutritionist, or sleep specialist.

3. Seek support.

Find out if the National Diabetes Prevention Program (NDPP) has offices near you. If so, stop by. Seek out diabetes support groups, in person or online. Join lifestyle groups like running clubs or fitness groups that align with your lifestyle goals.

Share your concerns with friends, family, colleagues, or therapists if you think it is appropriate. 

Rally them to your cause and stress the importance of them ceasing to encourage your unhealthier eating and drinking habits. This is about avoiding a serious health problem, so if everyone is on board, you’ll get there easier. A strong support group is invaluable in the face of a health challenge.


Prediabetes is both a warning sign and an opportunity. Most people who get diagnosed with Type 2 Diabetes were initially prediabetic, possibly for years (even decades), without ever knowing it.

Discovering you are prediabetic is a cloud with a silver lining—you have an opportunity to make healthy decisions that avoid Type 2 Diabetes with its gamut of severe symptoms and very bleak prognosis.

Prediabetes is characterized by elevated blood sugar metrics like Hemoglobin A1c and fasting plasma glucose levels. These levels are higher than normal, but not high enough to indicate a diagnosis of diabetes.

They do, however, indicate abnormalities in your body’s ability to process insulin, a precursor for Type 2 Diabetes.

Risk factors for prediabetes include:

  • Obesity or excess body weight, particularly an excess of belly fat
  • High LDL cholesterol, low HDL cholesterol
  • High triglycerides
  • Unhealthy habits like lack of exercise or excess calories in the diet
  • Disrupted sleep cycle by night shift work or sleep apnea
  • African American, Native American, Latin, or Pacific Islander heritage.

Prediabetes typically carries no symptoms, though observant patients may notice thirst, frequent urination, fatigue, or blurry vision.

Blood screening for prediabetes can be performed at a clinic or lab, or at home using a home screening kit.

If you suspect or discover that you have prediabetes, the condition can often be reversed before it progresses to T2D. Steps you can take to reverse prediabetes include:

  • Exercise regularly. Join workout buddies, fitness groups, or hire a personal trainer if necessary.
  • Adopt healthy sleep patterns. Go to bed and wake up at the same time; relax and read before sleeping; avoid screens like your TV, computer or phone before bed; sleep in a darkened room, cooled to 60-67 degrees Fahrenheit and with plenty of fresh air if possible.
  • Adopt a healthy diet. Cut out sugary drinks, limit grains, fatty dairy products, and red meats; eat low-fructose fruits in moderation; add fiber, unsaturated fats, and whole grains to your diet. A loss of 5%-7% of total body weight also goes a long way to alleviating the prediabetic condition. Then be sure to keep it off and especially avoid accruing belly fat.
  • Seek support for prediabetes. Check out the CDC’s National Diabetes Prevention Program (NDPP) or the help of online health platforms.
  • Quit smoking
  • Consider medication. Your doctor may prescribe medication to help you control your blood sugar levels.

With effort, determination, support, and the right mindset, patients with prediabetes can reverse the course of the disease and lead a healthy, active life.

Updated on
January 17, 2024
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