More than one in four Americans with diabetes don’t know they have it. That’s roughly 4.5% of all U.S. adults walking around with blood sugar levels high enough to cause damage, but without a formal diagnosis. The reason: type 2 diabetes often develops so slowly that symptoms are easy to miss or chalk up to something else. Knowing what to look for, who’s at higher risk, and which tests actually confirm a diagnosis can help you catch it early, when it’s most manageable.
Symptoms That Show Up With Both Types
Type 1 and type 2 diabetes share a core set of warning signs, all driven by the same underlying problem: too much sugar in your blood and not enough getting into your cells. The most common symptoms are urinating frequently (especially at night), feeling unusually thirsty, constant fatigue, and losing weight without trying. You may also notice blurred vision, cuts or wounds that heal slowly, increased hunger, and genital itching or recurring thrush infections.
The critical difference is speed. Type 1 symptoms tend to appear over days or weeks and can escalate quickly, sometimes to a medical emergency. Type 2 symptoms creep in over months or years, and many people have no noticeable symptoms at all in the early stages. That slow progression is exactly why type 2 diabetes so often goes undiagnosed.
Physical Signs You Might Not Connect to Diabetes
Some of the earliest visible clues aren’t the classic symptoms listed above. Dark, thick, velvety patches of skin in your armpits, groin, or the back of your neck point to a condition called acanthosis nigricans. It develops slowly, sometimes with itching or small skin tags nearby. This skin change is strongly tied to insulin resistance, the metabolic state that precedes and drives type 2 diabetes. If you notice these patches, it’s worth getting your blood sugar checked even if you feel fine otherwise.
Numbness or tingling in your hands and feet is another sign that often gets overlooked. High blood sugar damages small nerves over time, and by the time you feel it, the damage may have been building for years. Frequent infections, especially urinary tract infections or skin infections, can also signal that your immune system is struggling under the strain of elevated glucose.
Why You Can Have Diabetes and Feel Normal
CDC data from 2021 to 2023 shows that slightly more than one quarter of adults with diabetes had never been diagnosed. The rate of undiagnosed diabetes climbs with age: 1.3% of adults ages 20 to 39, 5.6% of adults 40 to 59, and 6.8% of adults 60 and older. It also rises sharply with body weight, from 1.6% among people at a normal weight to 7.9% among people with obesity.
These numbers exist because blood sugar can be dangerously elevated for years before it produces symptoms you’d notice in daily life. Your body compensates, your threshold for “normal” shifts, and the damage accumulates quietly in your blood vessels, kidneys, and nerves. This is why screening matters even when you feel perfectly healthy.
Who Should Get Screened
Current guidelines from both the U.S. Preventive Services Task Force and the American Diabetes Association recommend screening starting at age 35 for adults who are overweight or obese, with repeat testing every three years. If you have additional risk factors, screening may be recommended even earlier. Those risk factors include a family history of diabetes, physical inactivity, a history of gestational diabetes, or belonging to a racial or ethnic group with higher diabetes rates (including Black, Hispanic, Native American, and Asian American populations).
During pregnancy, screening for gestational diabetes typically happens between weeks 24 and 28. If you have an elevated risk, such as obesity, a previous pregnancy with gestational diabetes, or a strong family history, your doctor may test you at your very first prenatal visit.
The Tests That Confirm a Diagnosis
Three blood tests are used to diagnose diabetes, and all of them require a lab draw for an accurate result.
The A1C test measures your average blood sugar over the past two to three months. It doesn’t require fasting. The ranges are straightforward: below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or higher means diabetes.
The fasting blood sugar test measures your glucose after at least eight hours without eating. A result of 126 mg/dL or higher on two separate occasions confirms diabetes.
The oral glucose tolerance test is more involved. You fast for eight hours, then drink a solution containing 75 grams of sugar. Your blood is drawn one hour and two hours later. A two-hour reading of 200 mg/dL or higher indicates diabetes. This test is commonly used to diagnose gestational diabetes during pregnancy.
In some cases, if you already have classic symptoms like extreme thirst, frequent urination, and unexplained weight loss, a single random blood sugar reading of 200 mg/dL or higher is enough for a diagnosis without fasting or repeat testing.
Home A1C Kits: Useful but Limited
Over-the-counter A1C test kits are widely available at pharmacies, and they can give you a rough idea of where your blood sugar stands. But they aren’t accurate enough to diagnose diabetes. The FDA has specifically stated that home A1C tests should not be used for diagnosis. Studies comparing point-of-care devices to laboratory tests have found that these kits miss roughly 18% of people whose lab results would flag them as having elevated A1C. Their sensitivity simply isn’t precise enough to replace a lab draw.
A home kit showing a result in the prediabetes or diabetes range is a strong signal to get laboratory testing. But a normal-looking result on a home kit doesn’t guarantee you’re in the clear, especially if you have risk factors.
Prediabetes: The Window You Can Act On
If your A1C comes back between 5.7% and 6.4%, you’re in the prediabetes range. This isn’t a waiting room for diabetes. It’s a stage where blood sugar is elevated enough to cause some harm but where lifestyle changes can genuinely reverse course.
The Diabetes Prevention Program, a structured intervention studied extensively in the U.S., targets a weight loss of 5 to 7% of body weight over six months, combined with at least 150 minutes of physical activity per week. For someone weighing 200 pounds, that translates to losing 10 to 14 pounds. The program focuses on calorie tracking, nutrition changes, and building consistent exercise habits. These changes have been shown to significantly reduce the progression from prediabetes to type 2 diabetes.
The key takeaway with prediabetes is that it rarely announces itself. Most people discover it through routine bloodwork, not because they felt something was wrong. If you haven’t had your blood sugar checked in recent years and you’re over 35, carry extra weight, or have a family history of diabetes, a simple lab test can tell you where you stand.