The most common early signs of diabetes are frequent urination, unusual thirst, and unexplained weight loss. But many people with type 2 diabetes have no obvious symptoms at all and can go up to 10 years without knowing they have it. The only way to know for certain is a blood test, which your doctor can order or you can start with at home.
The Classic Warning Signs
Three symptoms show up so consistently in uncontrolled diabetes that doctors call them the “three Ps.” Frequent urination happens because your kidneys are working overtime to flush excess sugar from your blood. Increased thirst follows naturally, since your body is trying to replace all that lost fluid. And increased hunger kicks in because your body can’t properly use glucose for energy, so it signals you to eat more, even as you may be losing weight.
These three symptoms tend to appear together and feed off each other. You drink more because you’re urinating more, and you eat more because your cells are essentially starving despite high sugar levels in your bloodstream. If you’ve noticed this cycle, it’s a strong signal to get your blood sugar checked.
Subtler Signs You Might Miss
Beyond the classic trio, diabetes affects your body in ways that are easy to dismiss or blame on something else.
- Blurred vision. High blood sugar causes the lens of your eye to swell, temporarily changing your ability to focus. This can come and go.
- Slow-healing cuts and wounds. Elevated blood sugar disrupts the normal repair process. Your body gets stuck in the inflammatory stage of healing and struggles to rebuild tissue, grow new blood vessels, and close the wound.
- Tingling or numbness in your feet. Nerve damage from high blood sugar typically starts in the feet and works upward. Early signs include a “pins and needles” sensation, pain or heightened sensitivity (especially at night), and numbness or weakness.
- Frequent infections. Bacterial infections around the eyelids, hair follicles, and fingernails, as well as fungal infections in warm skin folds, are more common when blood sugar runs high.
- Dry, itchy skin. Poor circulation, which diabetes promotes, can leave your skin persistently dry and uncomfortable.
- Fatigue. When your cells can’t absorb glucose efficiently, you feel drained even after rest.
Skin Changes Linked to Insulin Resistance
One of the most overlooked clues is a skin condition called acanthosis nigricans: dark, velvety patches that appear in body creases like the neck, armpits, or groin. Sometimes they show up on the hands, elbows, or knees. These patches are a direct sign of insulin resistance and can indicate prediabetes or type 2 diabetes. They often appear before blood sugar levels are high enough to cause other symptoms, making them a valuable early warning.
Other skin changes include light brown or reddish round spots on the shins (sometimes called shin spots), small yellow or reddish-brown raised bumps on the hands and feet, and tight, thick, waxy skin on the fingers that makes joints stiff. None of these are guaranteed to mean diabetes, but if you’re seeing them alongside other symptoms on this list, the pattern is worth investigating.
Type 1 vs. Type 2: How Fast Symptoms Appear
If you’re an adult noticing gradual changes over months or years, you’re more likely looking at type 2 diabetes. Type 2 develops slowly, and symptoms can be so subtle in the early stages that many people have no idea anything is wrong. Some people live with it for a decade before getting diagnosed.
Type 1 diabetes is different. Symptoms appear quickly, often over just a few weeks, and tend to be more severe. Type 1 is most commonly diagnosed in children and young adults, though it can occur at any age. If someone who was previously healthy suddenly develops extreme thirst, rapid weight loss, and frequent urination, type 1 should be considered urgently.
How Diabetes Is Diagnosed
Three blood tests are used to diagnose diabetes, and any one of them can confirm it.
- A1C test. Measures your average blood sugar over the past two to three months. Normal is below 5.7%. Prediabetes falls between 5.7% and 6.4%. Diabetes is 6.5% or higher.
- Fasting blood glucose. Taken after you haven’t eaten for at least eight hours. Normal is below 100 mg/dL. Prediabetes is 100 to 125 mg/dL. Diabetes is 126 mg/dL or higher.
- Oral glucose tolerance test. Measures blood sugar two hours after drinking a sugary solution. Normal is below 140 mg/dL. Prediabetes is 140 to 199 mg/dL. Diabetes is 200 mg/dL or higher.
Your doctor will typically confirm the result with a second test on a different day before making a formal diagnosis, unless your symptoms are obvious and your numbers are clearly elevated.
Can You Test at Home?
Over-the-counter A1C test kits exist, but their accuracy varies significantly. A University of Florida study tested 219 people with diabetes using three popular home kits and compared the results to standard lab tests. One kit (Home Access) had 82% of its samples within acceptable accuracy. The other two fell far short, with only 46% and 29% of samples meeting the accuracy benchmark. A home test can give you a rough idea, but if your result is anywhere near the prediabetes or diabetes range, follow up with a lab test.
Quick Risk Check
Even without symptoms, certain factors raise your risk substantially. The National Institute of Diabetes and Digestive and Kidney Diseases publishes a simple scoring tool based on these questions: Are you over 40? Do you have a parent or sibling with diabetes? Have you been diagnosed with high blood pressure? Are you physically inactive? Are you above a healthy weight? For women: were you ever diagnosed with gestational diabetes or did you deliver a baby weighing 9 pounds or more?
Each “yes” adds points, and a score of 5 or higher means you’re at increased risk for type 2 diabetes. But even a lower score doesn’t rule it out, especially if you have prediabetes-range blood sugar without knowing it. If you check several of these boxes, getting a blood test is worthwhile even if you feel fine.
Emergency Signs That Need Immediate Care
In rare cases, undiagnosed diabetes leads to a dangerous condition called diabetic ketoacidosis, which happens when your body starts breaking down fat for energy so rapidly that it floods your blood with acids. This is most common in type 1 diabetes but can occur in type 2. Warning signs include fruity-smelling breath, nausea or vomiting, belly pain, shortness of breath, confusion, and extreme weakness. If you or someone near you has these symptoms alongside a blood sugar reading above 300 mg/dL, that’s a medical emergency.