Prediabetes: Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 17, 2026
Quick Answer
Prediabetes is a blood sugar level above normal but below the type 2 diabetes threshold [1] [3], often driven by insulin resistance [1] [6]. It usually causes no symptoms [1] [6], though darkened skin patches may appear [1] [5]. A1C, fasting blood sugar and glucose tolerance tests detect it [2]. Treatment includes diet changes, 150 minutes of weekly exercise [2] [3] and 5% to 7% weight loss [2] [3].
What the research says
Lifestyle change cut the risk of developing diabetes by more than half. In the Diabetes Prevention Program, 3,234 adults with elevated blood sugar were randomized to placebo, metformin, or a lifestyle program (at least 7% weight loss and 150 minutes of activity a week). Over an average of 2.8 years, lifestyle change reduced diabetes incidence by 58% and metformin by 31%, and lifestyle was significantly more effective than metformin (Knowler et al., N Engl J Med, 2002) [10].
Returning to normal blood sugar is linked to fewer heart problems. In a meta-analysis of 7 studies with 71,143 participants, people who reverted from prediabetes to normal blood sugar had a 28% lower risk of major cardiovascular events (hazard ratio 0.72) and a 31% lower risk of cardiovascular death (hazard ratio 0.69) than those with persistent prediabetes; the evidence is observational, so the authors urge cautious interpretation (Eisa & Barood, Can J Diabetes, 2026) [11].
Key Facts at a Glance
What Is Prediabetes?
Prediabetes means your blood sugar (glucose) level is higher than normal, but not high enough to be considered type 2 diabetes yet [1] [3]. Think of it as the middle zone between normal blood sugar and diabetes.
The condition has serious implications even in this "early" stage. Without lifestyle changes, adults and children with prediabetes are at high risk of developing type 2 diabetes [1]. Long-term damage to the heart, blood vessels, and kidneys may already be starting even before a diabetes diagnosis arrives [1].
There is genuinely good news. Progression from prediabetes to type 2 diabetes is not inevitable. Healthy eating, daily physical activity, and a stable healthy weight can bring blood sugar back to the normal range, and the same lifestyle changes that protect adults can help children's blood sugar return to normal too [1].
How Insulin Resistance Works
To understand prediabetes, it helps to understand insulin. When you eat, your body converts food into sugars. The pancreas, a gland sitting behind the stomach [1], releases the hormone insulin, which tells your cells to open up and take in that sugar so it can become energy. Insulin also lowers the amount of sugar in your blood. [1]
With insulin resistance, the cells don't react and don't open up. Sugar stays in the bloodstream instead of fueling the cells. The pancreas keeps working harder, producing more and more insulin to regulate blood sugar, until it wears out and can no longer produce enough [3]. At that point, blood sugar climbs into the diabetic range.
The Silent Nature of Prediabetes
Prediabetes usually has no signs or symptoms at all. [1] [6] It is most often picked up during a routine annual exam or routine blood work. This silence is exactly why screening matters: you generally cannot feel your way into a prediabetes diagnosis.
One possible visible clue is darkened skin on certain parts of the body, especially the neck, armpits, and groin [1] [5].
Signs and symptoms that suggest prediabetes has moved on to type 2 diabetes include increased thirst, frequent urination, increased hunger, fatigue, blurred vision, numbness or tingling in the feet or hands, frequent infections, slow-healing sores, and unintended weight loss [1].
When to see a doctor: See your health care provider if you're concerned about diabetes or notice any type 2 diabetes signs or symptoms [1]. Ask about blood sugar screening if you have any risk factors for diabetes.
What Causes Prediabetes?
The exact cause of prediabetes is unknown, but family history and genetics appear to play an important role [1]. What is clear is that people with prediabetes no longer process sugar (glucose) properly.
Most of the glucose in your body comes from the food you eat. When food is digested, sugar enters your bloodstream. Insulin normally allows that sugar to enter your cells, lowering the blood sugar level [1]. The pancreas also slows insulin secretion as blood sugar drops, keeping levels in balance.
In prediabetes, this process breaks down in one or both of two ways: the pancreas may not make enough insulin, or your cells become resistant to insulin and don't let as much sugar in [1]. Either way, sugar builds up in the bloodstream instead of fueling your cells.
What are the risk factors for prediabetes?
The same factors that raise the odds of type 2 diabetes also raise the risk of prediabetes.
Risk factor | What it means |
Weight | Overweight is a primary risk factor: more belly fat means more insulin-resistant cells [1] |
Waist size | Men with waists over 40 inches; women with waists over 35 inches [1] |
Diet | Red meat, processed meat, and sugar-sweetened beverages raise risk |
Inactivity | The less active you are, the greater the risk [1] |
Age | |
Family history | |
Race or ethnicity | |
Gestational diabetes | Diabetes during pregnancy raises risk for both mother and child [1] |
PCOS | |
Sleep | Obstructive sleep apnea increases insulin resistance risk [1] |
Smoking |
Other conditions tied to higher prediabetes risk include high blood pressure, low levels of HDL ("good") cholesterol, and high triglycerides (a type of fat in the blood) [1].
Metabolic Syndrome
When certain conditions occur together with obesity, they point to insulin resistance and raise the risk of diabetes, heart disease, and stroke [7]. A combination of three or more of these conditions is often called metabolic syndrome: high blood pressure, low HDL, high triglycerides, high blood sugar, and a large waist size [1].
What complications can prediabetes cause?
Prediabetes is not a harmless waiting room. It has been linked with long-term damage to the heart, blood vessels, and kidneys [1], even in people who never progress to type 2 diabetes. Prediabetes is also linked to unrecognized (silent) heart attacks [1].
If prediabetes progresses to type 2 diabetes, the condition can lead to high blood pressure, high cholesterol, heart disease, stroke, kidney disease, nerve damage, fatty liver disease, eye damage including vision loss, and amputations [1].
How can you prevent prediabetes?
Healthy lifestyle choices can help prevent prediabetes, and its progression to type 2 diabetes, even if diabetes runs in your family. The core habits are eating healthy foods, getting active, losing excess weight, controlling blood pressure and cholesterol, and not smoking [1].
How Is Prediabetes Diagnosed?
The American Diabetes Association recommends that diabetes screening for most adults begin at age 35 [2]. Screening should start before age 35 if you're overweight and have additional risk factors for prediabetes or type 2 diabetes [2].
If you've had gestational diabetes, your provider will likely check your blood sugar at least once every three years [2].
Three blood tests can diagnose prediabetes.
The A1C Test
The glycated hemoglobin (A1C) test shows your average blood sugar level over the past two to three months [2]. In general, below 5.7% is normal, between 5.7% and 6.4% is diagnosed as prediabetes [2] [6], and 6.5% or higher on two separate tests indicates diabetes [2]. Certain conditions can make the A1C test inaccurate, such as pregnancy or an uncommon form of hemoglobin [2].
The Fasting Blood Sugar Test
A blood sample is taken after you haven't eaten for at least eight hours or overnight [2]. Values below 100 mg/dL are normal, 100 to 125 mg/dL is diagnosed as prediabetes [2] [6], and 126 mg/dL or higher on two separate tests is diagnosed as diabetes [2].
The Oral Glucose Tolerance Test
This test is used less often, except during pregnancy [2]. You fast overnight, then drink a sugary liquid, and blood sugar is tested periodically over the next two hours. Below 140 mg/dL is normal, 140 to 199 mg/dL is consistent with prediabetes [2] [6], and 200 mg/dL or higher after two hours suggests diabetes [2].
If you have prediabetes, your blood sugar is typically checked at least once a year [2].
Testing Children
Type 2 diabetes is becoming more common in children and adolescents [2], likely because of rising childhood obesity. The American Diabetes Association recommends prediabetes testing for children who are overweight or obese [2] and have one or more additional risk factors: a family history of type 2 diabetes, belonging to a higher-risk race or ethnicity, low birth weight, or being born to a mother who had gestational diabetes. The normal, prediabetes, and diabetes ranges are the same for children and adults [2]. Children with prediabetes should be tested annually [2], or more often if their weight changes or symptoms appear.
How can you bring prediabetes blood sugar back to normal?
Healthy lifestyle choices can bring your blood sugar level back to normal, or at least keep it from rising toward type 2 diabetes levels.
Eat healthy foods. A diet rich in fruits, vegetables, nuts, whole grains, and olive oil is associated with a lower risk of prediabetes. Choose foods low in fat and calories and high in fiber [2], and eat a variety of foods so you can hit your goals without sacrificing taste or nutrition.
Be more active. Physical activity helps control weight, uses up sugar for energy, and helps the body use insulin more effectively. Aim for at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity per week [2], or a combination of both.
Lose excess weight. If you're overweight, losing just 5% to 7% of your body weight can significantly reduce type 2 diabetes risk [2] [3]. For a person who weighs 200 pounds (91 kilograms), that is about 14 pounds (6.4 kilograms) [2]. The goal is permanent changes to eating and exercise habits, not drastic or risky weight loss.
Stop smoking. Quitting improves how insulin works, which improves blood sugar [2] [8].
Take medications as needed. If you're at high risk of diabetes, your provider might recommend metformin (Glumetza) [2]. Medications to control cholesterol and high blood pressure might also be prescribed [2].
Treatment for Children
Children with prediabetes should follow the same lifestyle changes recommended for adults: losing weight, eating fewer refined carbohydrates and fats, getting more fiber, reducing portion sizes, eating out less often, and spending at least one hour a day in physical activity [2].
Medication generally isn't recommended for children with prediabetes unless lifestyle changes aren't improving blood sugar [2]. If medication is needed, metformin is usually the drug of choice [2].
What About Supplements and Alternative Therapies?
Many alternative therapies are promoted as ways to treat or prevent type 2 diabetes, but there is no definitive evidence that any alternative treatment works [2]. Options that have been mentioned for type 2 diabetes and are likely to be safe include cassia cinnamon, flaxseed, ginseng, magnesium, oats, soy, and xanthan gum.
Talk to your health care provider before trying dietary supplements or alternative therapies. Some can be harmful when combined with certain prescription medications [2], and your provider can help weigh the pros and cons of specific options.
How should you prepare for a prediabetes appointment?
You will likely start with your primary care provider, who may refer you to an endocrinologist (a diabetes specialist), a dietitian, or a certified diabetes educator [2].
Before your appointment, ask about pre-appointment restrictions. You may need to fast for at least eight hours [2] so your provider can measure your fasting blood sugar. Bring a list of symptoms and how long you've had them, all medications and supplements with doses, and key personal and medical information including recent life changes and stressors.
Helpful questions to ask include: How can I prevent prediabetes from turning into type 2 diabetes? Do I need medication, and what side effects can I expect? How can I best manage my other health conditions alongside this? How much exercise do I need each week? Are there foods I should avoid, and can I still eat sugar? Should I see a dietitian? Are there local programs for preventing diabetes?
Your provider will likely ask whether your weight has changed recently, whether you exercise regularly, and whether you have a family history of diabetes.
Conclusion
Prediabetes is a warning signal, not a life sentence. It usually arrives silently, with no symptoms to feel, which is why routine blood screening from age 35 (or earlier with risk factors) is one of the most valuable habits you can have. The damage that diabetes causes can already be underway in the prediabetes stage, but the same window means the most powerful treatment is also available: food, movement, weight loss, and quitting smoking. For people at high risk, metformin adds a safety net. Check your blood sugar yearly, take the small steps consistently, and you have a strong chance of keeping type 2 diabetes in the "never happened" column.
FAQ: Prediabetes
What is the difference between prediabetes and diabetes?
Prediabetes means blood sugar is higher than normal but below the diabetes threshold. On the A1C test, prediabetes is 5.7% to 6.4%, while diabetes is 6.5% or higher on two separate tests. Prediabetes raises your risk of type 2 diabetes and heart disease but can often be reversed with lifestyle changes.
What are the symptoms of prediabetes?
Prediabetes usually has no signs or symptoms at all, which is why it is often found on routine blood work. One possible visible sign is darkened skin patches on the neck, armpits, or groin. Symptoms such as increased thirst, frequent urination, and fatigue usually mean blood sugar has already reached the type 2 diabetes range.
Can prediabetes go back to normal?
Yes. In many cases prediabetes can be brought back to the normal range with healthy eating, regular physical activity (at least 150 minutes of moderate exercise weekly), modest weight loss of 5% to 7%, and quitting smoking. Medication such as metformin may be recommended for people at high risk.
At what age should I get screened for prediabetes?
The American Diabetes Association recommends screening begin at age 35 for most adults. Screening should start earlier if you are overweight and have additional risk factors such as a family history of diabetes or a history of gestational diabetes.
What foods should I avoid with prediabetes?
Diets high in red meat, processed meat, and sugar-sweetened beverages are associated with higher prediabetes risk. Instead, eat more fruits, vegetables, nuts, whole grains, and olive oil, choosing foods that are low in fat and calories and high in fiber.
Trusted External Resources
Centers for Disease Control and Prevention. Prediabetes: Your Chance to Prevent Type 2 Diabetes. Official overview of prediabetes, screening, and the National Diabetes Prevention Program.
National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance and Prediabetes. Explainer on how insulin resistance develops.
MedlinePlus. Prediabetes. Consumer health library entry from the U.S. National Library of Medicine.
Content reviewed and produced following the Rinnit editorial framework. Last updated: October 13, 2026.
This content is for educational purposes and is not a substitute for professional medical advice. Always consult a qualified health care provider for diagnosis and treatment decisions.
Related Reading
Learn more in our guide to A1C Test: Normal Levels, Prediabetes and Diabetes Ranges and What Affects Results.
Blood Tests: Common Types, How to Prepare, How Blood Is Drawn and What Results Mean explains the common blood tests used to check for and monitor this condition.
Fasting Blood Sugar Test: How to Prepare, Normal Levels and What Your Results Mean explains how a fasting blood sugar of 100 to 125 mg/dL can point to prediabetes.
Learn more in our guide to Physical Exam: What to Expect, What to Bring and How Often You Need One.
Blood Glucose Test: Normal Blood Sugar Levels, Prediabetes and Diabetes Ranges explains normal, prediabetes and diabetes blood sugar ranges.
Glucose Tolerance Test: Types, How to Prepare, What Happens and What Results Mean explains the 2-hour sugar-load test used to diagnose prediabetes, diabetes and gestational diabetes.
References
Mayo Clinic Staff. Prediabetes - Symptoms and causes. Mayo Clinic. September 10, 2026. https://www.mayoclinic.org/diseases-conditions/prediabetes/symptoms-causes/syc-20355278
Mayo Clinic Staff. Prediabetes - Diagnosis and treatment. Mayo Clinic. September 10, 2026. https://www.mayoclinic.org/diseases-conditions/prediabetes/diagnosis-treatment/drc-20355284
Centers for Disease Control and Prevention. Prediabetes – Your Chance to Prevent Type 2 Diabetes. Centers for Disease Control and Prevention. December 26, 2024. https://www.cdc.gov/diabetes/prevention-type-2/prediabetes-prevent-type-2.html
Centers for Disease Control and Prevention. The Surprising Truth About Prediabetes. Centers for Disease Control and Prevention. May 15, 2024. https://www.cdc.gov/diabetes/prevention-type-2/truth-about-prediabetes.html
American Academy of Dermatology. Diabetes: 10 warning signs that can appear on your skin. American Academy of Dermatology. Last updated May 22, 2024. https://www.aad.org/public/diseases/a-z/diabetes-warning-signs
National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance & Prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases. Last reviewed March 2025. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
American Heart Association. What is Metabolic Syndrome? American Heart Association. Last reviewed October 17, 2023. https://www.heart.org/en/health-topics/metabolic-syndrome/about-metabolic-syndrome
U.S. Food and Drug Administration. How Smoking Can Increase Risk for and Affect Diabetes. U.S. Food and Drug Administration. May 15, 2024. https://www.fda.gov/tobacco-products/health-effects-tobacco-use/how-smoking-can-increase-risk-and-affect-diabetes
U.S. Department of Health and Human Services. Current Guidelines. Office of Disease Prevention and Health Promotion. Last updated November 19, 2025. https://odphp.health.gov/our-work/nutrition-physical-activity/physical-activity-guidelines/current-guidelines
Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403. PMID 11832527. https://doi.org/10.1056/NEJMoa012512
Eisa N, Barood O. The association between reversion of prediabetes to normoglycemia and incident cardiovascular disease and mortality: a systematic review and meta-analysis. Can J Diabetes. 2026. PMID 42600933. https://doi.org/10.1016/j.jcjd.2026.08.003
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