Most people with prediabetes have no symptoms at all. According to the CDC, 8 in 10 adults with prediabetes don’t know they have it. The only reliable way to find out is through a blood test, but certain risk factors and subtle physical changes can tell you whether it’s time to get tested.
Why You Probably Won’t Feel It
Prediabetes means your blood sugar is higher than normal but not yet high enough to qualify as type 2 diabetes. The tricky part is that this elevated blood sugar rarely causes obvious symptoms. You won’t feel sick. You won’t feel tired in a way that stands out from normal life. Your body is quietly losing its ability to use insulin efficiently, but it compensates well enough that you don’t notice.
That said, there is one visible sign worth checking. A condition called acanthosis nigricans causes dark, thick, velvety patches of skin, most commonly on the back of the neck, in the armpits, or in the groin. These patches develop slowly and may feel itchy or have a slight odor. Skin tags sometimes appear in the same areas. This skin change is strongly linked to insulin resistance, the underlying process behind prediabetes. Not everyone with prediabetes develops it, but if you notice these patches, that’s a strong signal to get your blood sugar checked.
Risk Factors That Should Prompt Testing
The American Diabetes Association publishes a simple risk assessment based on seven factors. Each one adds to your overall likelihood of having prediabetes or early type 2 diabetes:
- Age: Risk increases at 40 and climbs further after 50 and 60.
- Weight: Being overweight or obese is the single biggest modifiable risk factor. For Asian Americans, risk begins at a lower weight, roughly 15 pounds below the threshold for other populations.
- Family history: A parent or sibling with diabetes raises your risk.
- Physical inactivity: A sedentary lifestyle independently increases risk.
- High blood pressure: A current or past diagnosis counts.
- Sex: Men carry slightly higher risk than women at the same age and weight.
- Gestational diabetes: Women who had high blood sugar during pregnancy remain at elevated risk years later.
The U.S. Preventive Services Task Force recommends screening for all adults aged 35 to 70 who are overweight or obese. If you’re Black, Hispanic/Latino, American Indian/Alaska Native, Native Hawaiian, or Pacific Islander, screening should start earlier because these populations develop diabetes at higher rates. Asian Americans should be screened at a lower BMI threshold (23 instead of 25) because metabolic risk begins at a leaner body composition in this group.
The Three Blood Tests That Diagnose It
Your doctor can use any of three tests. Each measures blood sugar in a different way, and the prediabetes ranges are well established.
The A1C test (also called HbA1c) is the most convenient. It measures your average blood sugar over the past two to three months by looking at how much sugar has attached to your red blood cells. No fasting required. A result between 5.7% and 6.4% means prediabetes. Below 5.7% is normal, and 6.5% or higher indicates diabetes.
Fasting plasma glucose requires you to skip food for at least 8 hours before the blood draw. A result between 100 and 125 mg/dL falls in the prediabetes range.
The oral glucose tolerance test measures how your body handles a sugar load. You drink a sugary solution, then have blood drawn two hours later. A result between 140 and 199 mg/dL indicates prediabetes.
Your doctor may use more than one test to confirm. It’s also worth knowing that certain conditions can throw off A1C accuracy. Iron deficiency anemia tends to push A1C readings falsely high, which could make your blood sugar look worse than it is. Conditions that destroy red blood cells faster than normal, like sickle cell disease or significant blood loss, push readings falsely low. Kidney failure can also distort results. If you have any of these conditions, a fasting glucose test or glucose tolerance test gives a more reliable picture.
What Prediabetes Actually Means for Your Future
A prediabetes diagnosis is not a guarantee that you’ll develop type 2 diabetes, but the odds are real. A large study published in BMJ Open Diabetes Research & Care found that among 45-year-olds with prediabetes, about 57% of women and 46% of men will eventually develop type 2 diabetes over their remaining lifetime if nothing changes. In the shorter term, roughly 9% to 14% progress to diabetes within 10 years depending on sex and which diagnostic criteria are used.
Those numbers might sound alarming, but they also mean a substantial portion of people with prediabetes never progress. And the progression rate drops significantly with intervention.
How Much Lifestyle Changes Actually Help
The most encouraging data comes from the Diabetes Prevention Program, a landmark clinical trial that followed over 3,200 adults with prediabetes. Participants who made intensive lifestyle changes, including moderate exercise (about 150 minutes per week) and enough dietary change to lose 5% to 7% of their body weight, reduced their risk of developing type 2 diabetes by 58% compared to a control group. That’s a dramatic reduction from relatively modest changes. For someone weighing 200 pounds, 5% to 7% means losing 10 to 14 pounds.
A medication-only group in the same trial reduced risk by 31%, which is meaningful but roughly half as effective as the lifestyle approach. Follow-up data over 21 years confirmed that these benefits persisted long term. The lifestyle group continued to develop diabetes at lower rates than the control group more than two decades later.
The specific changes that matter most are consistent but not extreme. Walking briskly for 30 minutes five days a week meets the exercise threshold. On the dietary side, reducing refined carbohydrates and added sugars while increasing fiber from vegetables, whole grains, and legumes has the most direct impact on blood sugar regulation. You don’t need to follow a rigid plan. The consistent theme across successful interventions is sustained, moderate change rather than short-term restriction.
How to Get Tested
If you have one or more of the risk factors listed above, request an A1C or fasting glucose test at your next primary care visit. These are routine blood tests covered by most insurance plans, especially when risk factors are present. Many pharmacies and community health centers also offer A1C screening without a doctor’s order, sometimes for free during awareness campaigns.
If your results come back in the prediabetes range, expect your doctor to recheck in three to six months and annually after that. This isn’t a one-time diagnosis. Your numbers can move in either direction depending on what you do next, and regular monitoring lets you see whether changes you’re making are working.