Prediabetes symptoms may not show up until you've been tested.

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During your latest doctor’s appointment, your physician breaks the news that you have prediabetes. It means your blood-sugar levels are elevated, but not high enough to be considered type 2 diabetes. You’re surprised not only by the diagnosis, but also by the fact that you experienced no prediabetes symptoms. After all, you reason, if you have a medical condition, wouldn’t you know it?

But with prediabetes symptoms, they aren’t a reliable indicator of your condition because most of the time prediabetes offers up no telltale warning signs. Once you do experience symptoms, there’s a good chance you’ve already progressed to type 2 diabetes.

To thwart this progression and safeguard your cardiovascular health, take action now by changing your lifestyle, improving your overall health (a diabetic diet will help), and, if necessary, following your doctor’s recommendations regarding medical therapy.

Prediabetes Symptoms Are Silent

Some 15 to 30 percent of people with prediabetes symptoms progress to type 2 diabetes within five years if they fail to make appropriate lifestyle changes, according to the Centers for Disease Control and Prevention (CDC).

Prediabetes and type 2 diabetes are diagnosed based on the following test results:

Test Results to Diagnose Prediabetes

• Fasting glucose test: 100–125 milligrams per deciliter (mg/dL)
• Oral glucose tolerance test: 140–199 mg/dL
• Hemoglobin A1c: 5.7–6.4 percent

Test Results to Diagnose Type 2 Diabetes

• Fasting glucose test: 126 mg/dL or higher
• Oral glucose tolerance test: 200 mg/dL or higher
• Hemoglobin A1c: 6.5 percent or higher

Trouble is, unless you see your doctor and get tested, there’s no way to know for certain if you’re on the path to type 2 diabetes. That’s because prediabetes symptoms are virtually nonexistent. Rather, symptoms aren’t likely to occur until your blood-sugar levels fall into the realm of type 2 diabetes. At that point, you may experience one or more of the following symptoms:

• Frequent urination
• Extreme thirst
• Hunger (despite eating)
• Severe fatigue
• Vision problems
• Slow-healing wounds
• Tingling, pain, or numbness in the extremities

Cause for Concern

Type 2 diabetes is a leading risk factor for cardiovascular disease, heart attack, and stroke, as well as chronic kidney disease. Diabetes causes painful diabetic nerve damage (neuropathy), and diabetic retinopathy (a leading cause of blindness), and in men it can contribute to erectile dysfunction. Also, several research investigations have identified a link between diabetes and dementia.

Even if you haven’t advanced to type 2 diabetes, there’s still cause for concern: Some research suggests that the risk of these diabetes complications may already be elevated in people with prediabetes

Understand Your Risk

Although you’re unlikely to recognize prediabetes symptoms, there are plenty of factors to suggest you’re at higher risk of prediabetes. You should be particularly on the lookout for prediabetes if you have a parent or sibling who had type 2 diabetes, you’re physically inactive, or if you’re obese, especially if your waist circumference (measured at the navel) is greater than 40 inches for men and 35 inches for women. You also should watch out for pre-diabetes if you have high blood pressure, low levels of high-density lipoprotein (HDL, “good”) cholesterol, and high levels of triglycerides (a type of fat in the blood).

Talk to your physician about screening for prediabetes. The American Diabetes Association (ADA) recommends screening for adults of any age who are overweight and have risk factors such as a family history of type 2 diabetes, a sedentary lifestyle, high blood pressure, low HDL cholesterol, and high triglycerides. If you have prediabetes, you should be checked for type 2 diabetes every year or two, according to the ADA.

Take Action

If you have prediabetes symptoms, losing 5 to 7 percent of your body weight with a healthful diet and exercise can reduce your risk of progressing to type 2 diabetes over the next three years by 31 percent, suggest results from the landmark Diabetes Prevention Program (DPP) study. In comparison, the study participants who received the diabetes drug metformin reduced their risk of progression by 31 percent.

Based on the DPP results, experts generally recommend that people with prediabetes reduce their risk of type 2 diabetes by lowering their intake of fat and calories, following a heart-healthy diet, and engaging in 30 minutes of moderate-intensity physical activity (such as walking) a day at least five days a week. (See also “Type 2 Diabetes Symptoms and Oral Medications.”) The ADA also recommends that doctors consider adding metformin to these lifestyle habits as an extra safeguard.

For further reading, see these University Health News posts:

• “What Causes Diabetes?“
• “Diabetes Symptoms: Do You Have Risk Factors?“
• “Prediabetes: Diet Advice That Can Keep You Healthy“

Originally published in 2016 and updated.