The most common early signs of diabetes are frequent urination, unusual thirst, and unexplained fatigue. But many people with type 2 diabetes have no obvious symptoms at all, and the condition can go undetected for up to 10 years. Knowing what to look for, and when to get tested even without symptoms, is the key to catching it early.
The Classic Warning Signs
When blood sugar rises above normal levels, your body sends several signals. The most recognizable ones are:
- Frequent urination. Excess sugar in the blood forces the kidneys to work harder to filter it out. When they can’t keep up, the sugar spills into urine and pulls fluid from your tissues along with it.
- Excessive thirst. That fluid loss causes dehydration, which triggers persistent thirst. Drinking more leads to urinating more, creating a cycle that’s hard to break.
- Unexplained weight loss. When your body can’t use sugar for energy properly, it starts breaking down fat and muscle instead. This is especially common in type 1 diabetes.
- Constant fatigue. Without enough sugar getting into your cells, your energy drops noticeably.
- Blurry vision. High blood sugar can cause the lens of the eye to swell, making it harder to focus.
Other signs that develop over time include slow-healing cuts or sores, frequent infections (especially yeast infections or urinary tract infections), tingling or numbness in your hands and feet, and red, swollen gums.
Type 1 and Type 2 Look Different
Type 1 diabetes tends to appear quickly, often over a few weeks. Symptoms come on fast and are hard to ignore: sudden weight loss, extreme thirst, and heavy fatigue that seems to arrive out of nowhere. It’s most often diagnosed in children, teenagers, and young adults, though it can develop at any age.
Type 2 diabetes is the opposite. It develops slowly, sometimes over years, and the symptoms creep in so gradually that many people write them off as normal aging or stress. You might feel a little more tired than usual, need to urinate a bit more often at night, or notice your vision isn’t quite as sharp. None of these feel alarming on their own, which is why type 2 is frequently caught through routine blood work rather than symptoms.
Skin Changes You Might Notice
One visible clue worth knowing about is patches of dark, thick, velvety skin that develop in body folds, most commonly the back of the neck, armpits, or groin. This condition, called acanthosis nigricans, is strongly linked to insulin resistance, the underlying problem in type 2 diabetes. The patches develop slowly and may feel slightly itchy or develop small skin tags. If you notice this kind of skin change, it’s a strong signal to get your blood sugar checked. People with acanthosis nigricans are significantly more likely to develop type 2 diabetes.
How Diabetes Is Actually Diagnosed
Symptoms alone can’t confirm diabetes. A blood test is required. The most common test is the A1C, which measures your average blood sugar over the past two to three months. The results break down into three categories:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or above
Your doctor may also use a fasting blood sugar test or an oral glucose tolerance test, which measures how your body handles sugar after drinking a sugary solution. In most cases, an abnormal result is confirmed with a second test on a different day before a diagnosis is made.
Who Should Get Tested Without Symptoms
Because type 2 diabetes can be silent for so long, screening guidelines exist for people who haven’t noticed anything wrong. The U.S. Preventive Services Task Force recommends that adults aged 35 to 70 who are overweight or obese get screened for prediabetes and type 2 diabetes, even with no symptoms at all.
If you’re from a population with higher diabetes rates, including Black, Hispanic/Latino, American Indian/Alaska Native, or Native Hawaiian/Pacific Islander communities, screening at a younger age is recommended. For Asian Americans, screening is advised at a lower body weight threshold (a BMI of 23 or above rather than the standard 25). A family history of diabetes, a history of gestational diabetes, or a diagnosis of polycystic ovary syndrome also warrants earlier testing.
Gestational Diabetes During Pregnancy
Gestational diabetes develops during pregnancy in people who didn’t have diabetes before. It rarely causes noticeable symptoms, which is why most pregnant women are screened with a glucose test between 24 and 28 weeks. The test involves drinking a sugary solution and having blood drawn to see how your body processes it. If the initial screen comes back high, a longer follow-up test over two or three hours confirms the diagnosis. Gestational diabetes usually resolves after delivery, but it raises your risk of developing type 2 diabetes later in life.
Emergency Signs That Need Immediate Attention
In some cases, diabetes announces itself through a medical emergency called diabetic ketoacidosis, or DKA. This happens most often with type 1 diabetes, though it can occur in type 2. When the body has almost no insulin available, it breaks down fat rapidly for fuel, producing acids called ketones that build up to dangerous levels in the blood.
The warning signs include fruity-smelling breath, nausea and vomiting, stomach pain, fast and deep breathing, dry skin and mouth, a flushed face, and extreme fatigue. If you’re vomiting and can’t keep fluids down, your breath smells fruity, or you’re having difficulty breathing, that’s a 911 situation. DKA can become life-threatening within hours.
Nerve and Vision Changes Over Time
Some people first suspect diabetes because of changes to their vision or sensation in their feet. Persistently high blood sugar damages small blood vessels, and the eyes and nerves in the extremities are particularly vulnerable. Early nerve damage often shows up as tingling, numbness, or a “pins and needles” feeling in the toes or fingers. It can also cause burning pain in the feet, especially at night.
Vision changes can start subtly with occasional blurriness, then progress to floaters (spots or dark strings drifting across your sight), dark areas in your vision, or difficulty seeing at night. These changes sometimes develop before a person even knows their blood sugar is high. Any sudden shift in vision, especially blurriness that comes and goes, is worth investigating with a blood sugar test.