The most common early signs of diabetes are frequent urination, unusual thirst, and fatigue that doesn’t improve with rest. But here’s the catch: many people with type 2 diabetes or prediabetes have no noticeable symptoms at all. About 8 in 10 adults with prediabetes don’t even know they have it. The only way to know for sure is a blood test, but understanding the warning signs and your personal risk factors can tell you whether it’s time to get one.
Symptoms That Point to Diabetes
Both type 1 and type 2 diabetes share a core set of symptoms driven by high blood sugar. These include urinating more often than usual, feeling thirstier than normal, blurry vision, slow-healing cuts or sores, and persistent tiredness or weakness. You might also notice frequent infections, including urinary tract infections, skin infections, or yeast infections. Some people feel unusually irritable or notice other mood changes they can’t explain.
Feeling hungry even right after eating is another signal. When your body can’t properly use the sugar in your blood for energy, it keeps sending hunger signals despite a full stomach.
How Type 1 and Type 2 Show Up Differently
Type 1 diabetes symptoms tend to develop fast, over a few days to weeks, and they’re usually hard to ignore. Unexplained weight loss is a hallmark of type 1 because the body starts breaking down fat and muscle for energy when it can’t produce insulin. Some people first discover they have type 1 when they develop a dangerous condition called diabetic ketoacidosis, which causes fruity-smelling breath, nausea, vomiting, stomach pain, and difficulty breathing.
Type 2 diabetes is sneakier. Symptoms can develop slowly over several years, and they’re often so mild that people brush them off. Many people don’t find out they have type 2 until they develop complications like numbness or tingling in their feet, vision loss, chest pain, or sexual problems. That’s why screening matters even when you feel fine.
Risk Factors That Should Prompt Testing
The U.S. Preventive Services Task Force recommends diabetes screening for adults aged 35 to 70 who are overweight (a BMI of 25 or higher) or obese (BMI 30 or higher). If you’re Asian American, the recommended BMI threshold is lower, at 23 or above, because diabetes risk rises at a lower weight in this population.
Several factors may warrant screening at a younger age:
- Racial or ethnic background: American Indian/Alaska Native, Black, Hispanic/Latino, Asian American, and Native Hawaiian/Pacific Islander populations have higher rates of diabetes.
- Family history: A parent or sibling with diabetes raises your risk significantly.
- History of gestational diabetes: Diabetes during pregnancy increases your chances of developing type 2 later.
- Polycystic ovarian syndrome (PCOS): This hormonal condition is linked to insulin resistance.
If any of these apply to you and you’re experiencing even mild symptoms, that’s a strong reason to get tested.
The Tests Your Doctor Will Use
There are three main blood tests used to diagnose diabetes, and your doctor may use one or a combination.
The A1C test measures your average blood sugar over the past two to three months. It doesn’t require fasting. A result below 5.7% is normal, 5.7% to 6.4% indicates prediabetes, and 6.5% or higher means diabetes.
The fasting blood sugar test checks your blood sugar after you haven’t eaten for at least eight hours, typically overnight. A result of 126 mg/dL or above indicates diabetes.
The glucose tolerance test involves fasting overnight, then drinking a sugary solution containing 75 grams of sugar. Your blood is drawn two hours later. A reading below 140 mg/dL is normal, 140 to 199 mg/dL suggests prediabetes, and 200 mg/dL or higher points to diabetes.
Doctors typically confirm the diagnosis with a second test on a different day, unless your symptoms and results are very clear-cut.
What About At-Home Tests?
You can buy at-home A1C test kits at most pharmacies, but their accuracy is a real concern. A University of Florida study tested three popular home kits against standard lab results using 219 people with diabetes. To be considered reliable, home test results should land within 5% of lab values at least 90% of the time. The best-performing kit met that standard only 82% of the time. The other two hit the mark in just 46% and 29% of samples.
A home kit might give you a rough idea, but it’s not reliable enough to rule diabetes in or out. If you’re worried, a proper lab test through your doctor is the only result worth trusting.
Emergency Warning Signs
Certain symptoms signal a medical emergency, particularly diabetic ketoacidosis. This is most common in type 1 diabetes but can occur in type 2 as well. Get to an emergency room or call 911 if you notice:
- Breath that smells fruity or sweet
- Rapid, deep breathing or difficulty breathing
- Vomiting that won’t stop, especially if you can’t keep fluids down
- Severe stomach pain combined with nausea
- Blood sugar readings above 300 mg/dL (if you have a meter)
These symptoms can escalate quickly. Diabetic ketoacidosis is treatable, but it requires immediate medical attention.
What to Do Next
If you’re reading this because something feels off, the most useful step is straightforward: ask for a blood sugar screening at your next doctor’s visit, or schedule one specifically. The tests are quick, inexpensive, and widely available. If you don’t have symptoms but match the risk profile (over 35, overweight, family history, or a higher-risk ethnic background), routine screening catches the problem years before complications develop. Prediabetes is reversible with lifestyle changes for many people, so early detection genuinely changes outcomes.