The most common early signs of diabetes are frequent urination, unusual thirst, and unexplained weight loss. But many people, especially those developing type 2 diabetes, have no obvious symptoms at all. The only way to know for sure is through a blood test, and current guidelines recommend screening starting at age 35 for anyone with overweight or obesity.
Symptoms That Point to Diabetes
Type 1 and type 2 diabetes share a core set of warning signs: urinating more often than usual, feeling thirstier than normal, and losing weight without trying. These happen because your body can’t move sugar from your blood into your cells efficiently. The excess sugar spills into your urine, pulling water with it, which drives the thirst and frequent bathroom trips. Your body starts breaking down fat and muscle for energy instead, causing the weight loss.
Beyond those three hallmarks, you may notice:
- Blurry vision that comes and goes
- Cuts or sores that heal slowly
- Tingling or numbness in your hands or feet
- Fatigue that doesn’t improve with rest
- Increased hunger even after eating
In children, new or unexplained bed-wetting can be an early sign of type 1 diabetes, even in kids who have been dry at night for years.
The key difference between the two types is speed. Type 1 symptoms tend to appear suddenly over days or weeks. Type 2 develops so gradually that many people live with elevated blood sugar for years before noticing anything wrong. That slow onset is exactly why screening matters.
Why You Can Have Diabetes Without Knowing It
Prediabetes, the stage where blood sugar is elevated but not yet in the diabetic range, almost never causes noticeable symptoms. Roughly 98 million American adults have prediabetes, and most are unaware. Without lifestyle changes, prediabetes carries a high risk of progressing to full type 2 diabetes. By the time classic symptoms like excessive thirst appear, blood sugar levels have often been damaging blood vessels, nerves, and organs for years.
This is why relying on how you feel is not a reliable strategy. A normal-feeling day doesn’t rule out dangerously elevated blood sugar.
Who Should Get Screened
In 2022, the American Diabetes Association lowered its recommended screening age to 35 for adults with overweight or obesity. The U.S. Preventive Services Task Force made a similar update in 2021, recommending screening for people aged 35 to 70 who carry extra weight. Both organizations recommend repeating the test every three years if results are normal.
The ADA also recommends screening at any age for adults with overweight or obesity who have at least one additional risk factor. Those risk factors include:
- A parent or sibling with type 2 diabetes
- A history of gestational diabetes
- Being physically inactive
- Being African American, Hispanic, Native American, Asian American, or Pacific Islander
- High blood pressure or abnormal cholesterol levels
- A history of polycystic ovary syndrome
If several of these apply to you, screening is worth pursuing even if you feel perfectly healthy.
The Blood Tests That Confirm a Diagnosis
Diabetes is diagnosed with a simple blood draw, not a finger-prick monitor from the pharmacy. The most common test is the fasting plasma glucose test, which measures your blood sugar after you haven’t eaten overnight.
- Normal: 99 mg/dL or below
- Prediabetes: 100 to 125 mg/dL
- Diabetes: 126 mg/dL or higher
A result in the diabetes range is typically confirmed with a second test on a different day. Your doctor may also order an A1C test, which reflects your average blood sugar over the past two to three months and doesn’t require fasting. An A1C of 6.5% or higher indicates diabetes, while 5.7% to 6.4% falls in the prediabetes range.
A third option is the oral glucose tolerance test, where you drink a sugary solution and have your blood drawn two hours later. A reading of 200 mg/dL or above at the two-hour mark confirms diabetes.
Can a Home Glucose Monitor Tell You?
Over-the-counter glucose meters, the kind you prick your finger for, can give you a rough snapshot of your blood sugar. But they are not accurate enough to diagnose diabetes. One study comparing finger-prick meters to laboratory blood draws found the average difference between the two readings was about 17.5 mg/dL. That gap matters when the line between prediabetes and diabetes is a single point (125 vs. 126 mg/dL).
A home meter showing a reading over 200 mg/dL is a strong signal that something is wrong and worth immediate follow-up. But a normal-looking reading on a home device doesn’t guarantee your levels are actually normal. These meters are designed to help people who already have a diagnosis manage their daily blood sugar, not to replace lab testing.
Emergency Warning Signs
In some cases, diabetes announces itself as a medical emergency. This is most common with type 1 diabetes and is called diabetic ketoacidosis (DKA). It happens when the body has almost no insulin and starts rapidly breaking down fat, producing acids called ketones that make the blood dangerously acidic.
Signs of DKA include:
- Breath that smells fruity or sweet
- Fast, deep breathing
- Nausea, vomiting, or stomach pain
- Extreme fatigue or confusion
- Dry mouth and flushed skin
If you or someone around you has fruity-smelling breath combined with vomiting or difficulty breathing, call 911. DKA can become life-threatening within hours. It sometimes occurs as the very first sign of type 1 diabetes in people who didn’t know they had it, including children and young adults who appeared healthy days earlier.
What a Prediabetes Result Means
A fasting blood sugar between 100 and 125 mg/dL puts you in the prediabetes category. This isn’t a diagnosis of diabetes, but it’s not a clean bill of health either. It means your body is already struggling to regulate blood sugar, and the trajectory points toward type 2 diabetes without intervention.
The practical upside of catching prediabetes is that it responds well to lifestyle changes. Losing 5% to 7% of your body weight (about 10 to 14 pounds for someone who weighs 200) and getting 150 minutes of moderate activity per week, like brisk walking, has been shown to cut the risk of progressing to type 2 diabetes by more than half. These changes don’t have to be dramatic. Consistent, modest adjustments to diet and movement make a measurable difference at this stage, which is exactly why early screening is so valuable.