Many people with diabetes, especially type 2, don’t realize they have it. The condition can develop silently over years, sometimes a decade or more, before symptoms become obvious enough to notice. Knowing the warning signs, your personal risk factors, and which tests to ask for are the three keys to catching it early.
Symptoms That Signal High Blood Sugar
The classic signs of diabetes all stem from one problem: too much glucose in your bloodstream. When your body can’t move sugar into cells efficiently, it tries to flush the excess through your kidneys. That leads to frequent urination, which in turn makes you dehydrated and thirsty. Meanwhile, your cells are starved for energy despite all that circulating sugar, so you feel hungrier than usual and may lose weight without trying.
Those four symptoms (thirst, frequent urination, increased hunger, unexplained weight loss) are the most recognized, but they’re not the only ones. High blood sugar also causes blurred vision, fatigue, and slow-healing cuts or sores. One easy-to-miss sign shows up on your skin: dark, velvety patches in body creases like the neck, armpits, or groin. This condition, called acanthosis nigricans, signals insulin resistance and can appear before blood sugar levels are high enough for a diabetes diagnosis. It’s especially common in people with obesity.
Type 1 and Type 2 Feel Different
How quickly symptoms appear depends on which type of diabetes you’re developing. Type 1 tends to come on fast, over weeks, and usually strikes children, teens, or young adults. The symptoms are hard to ignore because they escalate rapidly.
Type 2 is the opposite. It develops slowly, often over years, and the early signs are subtle enough to dismiss as aging, stress, or being out of shape. Some people live with type 2 diabetes for up to 10 years without knowing it. By the time symptoms are obvious, blood sugar levels may have been elevated long enough to cause damage to nerves, kidneys, or eyes. That slow, quiet progression is exactly why screening matters even when you feel fine.
Who Should Get Screened
The U.S. Preventive Services Task Force recommends that adults ages 35 to 70 who are overweight or obese get screened for prediabetes and type 2 diabetes, even without symptoms. But several factors can warrant earlier or more frequent testing:
- Family history: a parent or sibling with type 2 diabetes
- Ethnicity: African American, Hispanic/Latino, American Indian, Alaska Native, Native Hawaiian, Pacific Islander, or Asian American populations face higher risk
- Lifestyle: being physically active fewer than three times a week
- Medical history: gestational diabetes, giving birth to a baby over 9 pounds, polycystic ovary syndrome (PCOS), or non-alcoholic fatty liver disease
For Asian Americans, screening is recommended at a lower body weight threshold (a BMI of 23 rather than 25) because type 2 diabetes develops at lower body weights in this population. For type 1, the main known risk factors are having a close family member with the condition and being younger, though it can occur at any age.
The Tests Your Doctor Will Use
Three blood tests are used to diagnose diabetes, and any one of them can confirm it. Your doctor will typically choose based on convenience and your situation.
The A1C test is the most common starting point because it doesn’t require fasting. It measures your average blood sugar over the past two to three months. A result below 5.7% is normal. Between 5.7% and 6.4% means prediabetes. At 6.5% or higher, you have diabetes.
The fasting blood sugar test requires you to skip food for at least eight hours before a blood draw. Normal is below 100 mg/dL. Prediabetes falls between 100 and 125 mg/dL. Diabetes is diagnosed at 126 mg/dL or higher.
The oral glucose tolerance test is more involved. You fast overnight, drink a sugary solution at the lab, then have your blood drawn two hours later. Normal is below 140 mg/dL. Prediabetes is 140 to 199 mg/dL. Diabetes is 200 mg/dL or higher.
There’s also a random blood sugar test, which can be done at any time without fasting. A result of 200 mg/dL or above, combined with symptoms like excessive thirst or frequent urination, points to diabetes. This test is useful when symptoms are already present and your doctor wants a quick answer.
In most cases, an abnormal result will be confirmed with a second test on a different day before a formal diagnosis is made.
What Prediabetes Means
If your numbers fall in the prediabetes range (A1C of 5.7% to 6.4%, or fasting glucose of 100 to 125 mg/dL), your blood sugar is higher than normal but not high enough to qualify as diabetes. This isn’t a safe zone to ignore. Prediabetes means your body is already struggling with insulin, and without changes, it often progresses to type 2 diabetes.
The good news is that prediabetes is reversible. Losing a moderate amount of weight, increasing physical activity, and improving your diet can bring blood sugar back to normal levels. Addressing insulin resistance at this stage is also the most effective treatment for those dark skin patches associated with the condition.
Screening During Pregnancy
Gestational diabetes is a separate form that develops during pregnancy, typically in the second trimester. Most pregnant people are screened between 24 and 28 weeks. The initial test involves drinking a glucose solution and having blood drawn one hour later. If your blood sugar comes back at 140 mg/dL or higher, you’ll return for a longer fasting version of the test with blood draws at multiple time points. High readings at two or more of those draws confirm gestational diabetes.
Your risk is higher if you had gestational diabetes in a previous pregnancy, have a family history of type 2 diabetes, have obesity, are over 25, or have PCOS. Gestational diabetes usually resolves after delivery, but it significantly raises your risk of developing type 2 diabetes later in life, making follow-up screening important in the years after pregnancy.
What to Do if You Suspect Diabetes
If you recognize symptoms like unusual thirst, frequent trips to the bathroom, blurred vision, or slow-healing wounds, a simple blood test can give you a clear answer. If you don’t have symptoms but carry risk factors, don’t wait for something to feel wrong. The whole point of screening is to catch elevated blood sugar before it causes damage.
A standard blood panel at a routine checkup can include fasting glucose, and an A1C test can be added with a simple request. Many pharmacies also offer A1C testing without a prescription, though a formal diagnosis still requires follow-up with a healthcare provider. The earlier diabetes or prediabetes is identified, the more options you have to manage it effectively and prevent complications.