--- title: "Prediabetes: A1C and glucose ranges, symptoms, next steps" description: "Prediabetes per the CDC and NIH: A1C 5.7% to 6.4%, fasting 100 to 125 mg/dL. Why it rarely shows symptoms, who gets tested, and what lowers the risk." canonical: https://glucosebench.com/prediabetes alternate_html: https://glucosebench.com/prediabetes language: en-US last_updated: 2026-09-27 type: guia --- # Prediabetes: a number worth acting on, usually without a symptom 1. [Home](https://glucosebench.com/) 2. [Blood sugar basics](https://glucosebench.com/blood-sugar) 3. Prediabetes: a number worth acting on, usually without a symptom Prediabetes is usually found on a lab report, not felt. The steps shown to lower the risk are specific and measured, and none of them comes in a bottle. By **GlucoseBench editorial team**Updated September 27, 2026 ![Prediabetes: a number worth acting on, usually without a symptom](https://glucosebench.com/img/guia-prediabetes-640.webp) Short answer Prediabetes means your blood sugar is higher than normal but not high enough for a type 2 diabetes diagnosis. The ranges are an A1C of 5.7% to 6.4%, a fasting blood sugar of 100 to 125 mg/dL, or 140 to 199 mg/dL two hours into a glucose tolerance test. More than 2 in 5 American adults have it, according to the CDC, and it often causes no clear symptoms for years. A blood test finds it, and modest weight loss plus regular activity lower the odds that it turns into type 2 diabetes. ## The prediabetes range on each test Every value inside a range counts the same way on these charts, whether it's an A1C of 5.7, 5.8 or 6.2, or a fasting result of 110. For the A1C, NIDDK adds one nuance: within 5.7 to 6.4 percent, "the higher the A1C, the greater the risk of diabetes." Test Prediabetes range How the test is done A1C 5.7% to 6.4% No fasting; reflects roughly the past 3 months Fasting plasma glucose 100 to 125 mg/dL After an overnight fast of at least 8 hours Oral glucose tolerance test 140 to 199 mg/dL Measured 2 hours after a glucose drink Sources: NIDDK, "Insulin Resistance & Prediabetes" (last reviewed March 2025), and CDC, "Diabetes Testing" (May 15, 2024), read on September 27, 2026. The quote in the intro is from NIDDK, "The A1C Test & Diabetes." NIDDK also notes that "in people with certain health conditions, the A1C test may miss prediabetes." ## Why most people with prediabetes don't know it The CDC is blunt: "You can have prediabetes for years but have no clear symptoms. It often goes undetected until serious health problems such as type 2 diabetes show up." NIDDK says people with prediabetes usually have no symptoms, though some may have symptoms similar to diabetes. A list of "prediabetes symptoms" can't settle much. A blood test can. So the CDC ties testing to risk factors, not to how you feel. Its list: being overweight; being 45 or older; having a parent, brother or sister with type 2 diabetes; being physically active less than 3 times a week; ever having gestational diabetes; giving birth to a baby who weighed more than 9 pounds; and having polycystic ovary syndrome. African American, Hispanic/Latino American, American Indian, Alaska Native, Pacific Islander and some Asian American people are also at higher risk. The CDC's site has a short risk test if you want a quick read on yours. NIDDK's testing age is lower than the CDC's 45: "Your health care professional may order tests for prediabetes if you're age 35 or older, or if you have overweight or obesity and other risk factors for prediabetes and type 2 diabetes." Prediabetes raises the odds of type 2 diabetes without sealing them. NIDDK says "people with prediabetes have a high chance of developing type 2 diabetes within 5 to 10 years," and also that "not everyone with prediabetes develops type 2 diabetes." ## What lowers the risk, in short The CDC's prevention advice fits in two lines: for people with overweight, lose 5% to 7% of body weight, plus 150 or more minutes a week of brisk walking or something like it. Its National Diabetes Prevention Program, built around those changes, lowers the risk of type 2 diabetes by 58%. NIDDK adds yearly testing for type 2 diabetes once you have prediabetes, and notes that your doctor may prescribe medicine such as metformin. Our prediabetes diet guide covers the program and the eating side in detail. ## Supplements and prediabetes: one finding, with limits NCCIH, the NIH's center for complementary health, reports a single supplement finding on the question that matters most here, whether prediabetes turns into type 2 diabetes. It's vitamin D. A 2020 review of 9 studies (43,559 participants) found that "vitamin D supplementation at moderate-to-high doses (at least 1,000 IU/day) significantly reduced the risk of type 2 diabetes in people with prediabetes." The same review found no reduction in studies of lower doses in the general population. Another 2020 review (8 studies, 4,896 participants) pointed the same way, but suggested "the benefit may be limited to people who do not have obesity." The NIH's Office of Dietary Supplements reads the evidence more cautiously: "clinical trials in people with and without diabetes show that supplemental vitamin D does not improve blood sugar levels, insulin resistance, or hemoglobin A1c levels", and "vitamin D supplements don’t stop most people with prediabetes from developing diabetes." Extra vitamin D carries its own risk. NCCIH says "high levels of vitamin D are almost always caused by consuming excessive amounts of vitamin D from dietary supplements." If you already take vitamin D, tell your doctor before adding more of it from any source. None of this is part of the CDC's program, which works through weight, activity and support. A supplement shouldn't take the place of any of those steps, and if you take medication, check with your doctor before starting one. ## Frequently asked questions **What are the symptoms of prediabetes?** Usually none you'd notice. The CDC says you can have it for years without clear symptoms, and NIDDK says some people have symptoms similar to diabetes. It's found with a blood test. **What A1C is prediabetes?** 5.7% to 6.4%. Below 5.7% is normal, and 6.5% or above is in the diabetes range. **Is an A1C of 5.7 prediabetes?** Yes. 5.7% is the lowest value in the prediabetes range. Within that range, NIDDK says a higher A1C means a greater risk of diabetes, so the bottom of the range is still a reason to talk to your doctor. **What blood sugar level is prediabetes?** A fasting blood sugar of 100 to 125 mg/dL, or 140 to 199 mg/dL two hours into an oral glucose tolerance test. **Does prediabetes always turn into type 2 diabetes?** No. NIDDK says not everyone with prediabetes develops type 2 diabetes. Losing some weight and staying active lower the risk, according to the CDC. **Can supplements help with prediabetes?** The only finding NCCIH reports on preventing type 2 diabetes in people with prediabetes is for vitamin D, in studies that used at least 1,000 IU a day, and it comes with limits. It's no substitute for the steps the CDC lists. Ask your doctor before starting any supplement. ## Related pages Blood sugar basics ### [Eating with prediabetes: a plate borrowed from the CDC's diabetes advice](https://glucosebench.com/prediabetes-diet) The CDC's prediabetes page doesn't give a menu; it sets two targets: lose around 5% to 7% of your body weight if you have overweight, and get at least 150 minutes a week… Read more Blood sugar basics ### [Insulin resistance: the condition a symptom checklist can't find](https://glucosebench.com/insulin-resistance) Insulin resistance is "a condition in which your body doesn't respond to insulin the way it should," according to the NIH's diabetes institute (NIDDK). Read more Blood sugar basics ### [Your A1C result, read against the NIH's cutoffs and the CDC's chart](https://glucosebench.com/a1c-levels) A normal A1C is below 5.7%. Read more Blood sugar basics ### [Fasting blood sugar: three cutoffs and one blood draw](https://glucosebench.com/fasting-blood-sugar) The CDC's cutoffs for fasting blood sugar: 99 mg/dL or below is normal, 100 to 125 mg/dL is prediabetes, and 126 mg/dL or above is diabetes. Read more Updated September 27, 2026. [See our full method](https://glucosebench.com/how-we-choose) --- ## GlucoseBench - GlucoseBench, published by Grupo Marfre Automação e Tecnologia (Contagem, Brazil) - Email: contact@glucosebench.com - Home: https://glucosebench.com/ - llms.txt: https://glucosebench.com/llms.txt · llms-full.txt: https://glucosebench.com/llms-full.txt · sitemap: https://glucosebench.com/sitemap.xml