The most common early signs of diabetes are urinating more often than usual, feeling unusually thirsty, and losing weight without trying. But type 2 diabetes, the most common form, often develops so gradually that many people have it for years without noticing anything wrong. The only way to know for sure is a blood test, and understanding which symptoms and risk factors apply to you can help you decide whether it’s time to get one.
Early Symptoms to Watch For
Both type 1 and type 2 diabetes share a core set of symptoms: frequent urination, increased thirst, and increased hunger. These happen because your body can’t move sugar from your blood into your cells effectively. The excess sugar spills into your urine, pulling water with it, which is why you pee more and feel dehydrated. Your cells, starved of fuel despite all that sugar in your bloodstream, send hunger signals even when you’ve eaten enough.
Unexplained weight loss is another hallmark. When your body can’t use blood sugar for energy, it starts breaking down fat and muscle instead. If you’re losing weight without changing your diet or exercise habits, that’s worth paying attention to, especially combined with the symptoms above.
Other signs that often show up early include blurry vision, fatigue that doesn’t improve with rest, numbness or tingling in your hands or feet, and wounds or cuts that heal unusually slowly. None of these on their own confirm diabetes, but a cluster of two or three should prompt a blood test.
Type 1 vs. Type 2: How They Show Up Differently
Type 1 diabetes tends to appear suddenly, especially in children. Symptoms can escalate over just a few weeks, going from mild thirst to severe weight loss and exhaustion quickly. This is because the immune system destroys the cells that make insulin, and once enough are gone, blood sugar rises fast.
Type 2 diabetes is a different story. It develops over years as your body gradually becomes resistant to insulin. Symptoms creep in so slowly that many people chalk them up to aging, stress, or being busy. You might not connect getting up to pee at night with the extra thirst you’ve been feeling during the day. That’s why nearly 1 in 5 people with type 2 diabetes don’t know they have it.
Skin Changes That Signal Insulin Resistance
One physical sign you can actually see is patches of dark, thick, velvety skin in body folds and creases, most commonly the back of the neck, armpits, and groin. This condition, called acanthosis nigricans, develops slowly and is closely tied to insulin resistance. The affected skin might also be itchy, have an odor, or develop small skin tags. People with these skin changes are much more likely to develop type 2 diabetes if they haven’t already. If you notice this on your body, it’s a strong reason to get your blood sugar checked.
Risk Factors That Raise Your Odds
Certain factors make diabetes more likely, even before symptoms appear. For type 2 diabetes and prediabetes, the major ones include:
- Weight: Having overweight or obesity (a BMI of 25 or higher, or 23 or higher for people of Asian descent)
- Age: Being 45 or older
- Family history: Having a parent or sibling with type 2 diabetes
- Activity level: Being physically active fewer than three times a week
- Pregnancy history: Having had gestational diabetes or delivering a baby who weighed over 9 pounds
- Other conditions: Having non-alcoholic fatty liver disease or polycystic ovary syndrome (PCOS)
For type 1 diabetes, the strongest known risk factor is having a parent or sibling with the condition. It’s less predictable than type 2 and isn’t linked to weight or lifestyle.
When to Get Screened
Current guidelines recommend that all adults begin screening at age 35, even without symptoms or risk factors. If your results are normal, repeat testing every three years. But if you’re younger than 35 and carry extra weight plus any of the risk factors listed above, screening should start sooner. People of Asian descent qualify for earlier screening at a lower BMI threshold of 23.
If you’ve already been told you have prediabetes, your doctor will likely want to retest more frequently since prediabetes can progress to full diabetes within a few years without lifestyle changes.
The Blood Tests That Confirm a Diagnosis
Three main blood tests are used to diagnose diabetes, and they each measure blood sugar in a slightly different way.
A1C Test
This measures your average blood sugar over the past two to three months. It doesn’t require fasting. A result below 5.7% is normal. Between 5.7% and 6.4% falls in the prediabetes range. A reading of 6.5% or higher on two separate tests means diabetes.
Fasting Blood Sugar Test
You fast overnight, then have your blood drawn in the morning. A fasting level under 100 mg/dL is normal. Between 100 and 125 mg/dL indicates prediabetes. If it’s 126 mg/dL or higher on two separate tests, that confirms diabetes.
Glucose Tolerance Test
You drink a sugary liquid, then have your blood sugar measured two hours later to see how your body handles a sugar load. A two-hour result of 200 mg/dL or above indicates diabetes. This test is commonly used during pregnancy to check for gestational diabetes.
Doctors typically confirm a diagnosis with at least two abnormal results, either from the same test repeated or from two different tests. A single high reading usually triggers a follow-up rather than an immediate diagnosis.
Vision Changes Can Be a Hidden Clue
Diabetes affects the tiny blood vessels in your eyes, and the earliest stage of damage often produces no symptoms at all. Over time, weakened blood vessels in the retina can leak, causing blurry vision, dark spots, or trouble seeing colors. People with diabetes are also twice as likely to develop glaucoma and more likely to develop cataracts at a younger age, because high blood sugar causes deposits to build up in the eye’s lens.
If you’ve noticed your vision getting blurry or you’re struggling with glare more than you used to, it’s worth mentioning to your doctor, particularly if you have other risk factors for diabetes.
Emergency Warning Signs
In some cases, particularly with undiagnosed type 1 diabetes, blood sugar can spike to dangerous levels and trigger a condition called diabetic ketoacidosis (DKA). This happens when the body, unable to use sugar for fuel, breaks down fat so rapidly that it produces toxic acids called ketones.
Warning signs of DKA include fruity-smelling breath, fast and deep breathing, nausea and vomiting, stomach pain, extreme fatigue, dry skin and mouth, and a flushed face. If your blood sugar is 300 mg/dL or above, your breath smells fruity, or you’re vomiting and can’t keep food or fluids down, that’s a medical emergency. DKA can become life-threatening within hours.
While DKA is more common in type 1 diabetes, it can also occur in type 2 under severe illness or stress. Recognizing these symptoms matters because DKA is sometimes the very first sign that someone has diabetes at all.
What You Can Do Right Now
If you’re reading this because something feels off, the simplest next step is a fasting blood sugar or A1C test. Both are routine, inexpensive, and available at virtually any lab or clinic. Many pharmacies also offer A1C screening without a prescription.
If you don’t have symptoms but your risk factors put you in a higher category, the same tests apply. Catching diabetes early, or catching it at the prediabetes stage, makes a significant difference. At the prediabetes stage, increasing physical activity, eating a healthier diet, and losing even a modest amount of weight can slow or prevent progression to type 2 diabetes.