About 12% of the U.S. population, or 40.1 million people, currently have diabetes. That figure includes both diagnosed and undiagnosed cases, based on 2023 estimates from the CDC’s National Diabetes Statistics Report. Roughly 1 in 12 Americans is living with the condition, and more than a quarter of them don’t know it.
The Full Count: Diagnosed and Undiagnosed
Of the 40.1 million Americans with diabetes, 29.1 million have been formally diagnosed. The remaining 11 million are undiagnosed, meaning they have blood sugar levels that meet the threshold for diabetes but haven’t received a diagnosis from a healthcare provider. That works out to about 27.6% of all adults with diabetes walking around unaware of their condition.
Undiagnosed diabetes is a serious concern because chronically elevated blood sugar damages blood vessels, nerves, kidneys, and eyes over time, even when a person feels fine. Many people discover they have diabetes only after a complication surfaces, like blurry vision, slow-healing wounds, or kidney problems. A simple blood test can catch it years earlier.
How Diabetes Is Defined
Doctors use several blood tests to diagnose diabetes, all measuring how well the body handles sugar. A fasting blood glucose level of 126 mg/dL or higher qualifies as diabetes. So does a reading of 200 mg/dL or higher on an oral glucose tolerance test, which measures blood sugar two hours after drinking a sugary liquid. A random blood sugar check of 200 mg/dL or higher, combined with symptoms like extreme thirst or frequent urination, also meets the bar.
The most commonly used screening tool is the A1C test, which reflects average blood sugar over the previous two to three months. An A1C between 5.7% and 6.4% indicates prediabetes. At 6.5% or above, the diagnosis is diabetes.
Type 1 vs. Type 2
The vast majority of cases are type 2 diabetes, which accounts for roughly 90 to 95% of all diabetes in the U.S. In type 2, the body still produces insulin but can’t use it efficiently, a problem that develops gradually and is closely tied to weight, physical activity, and genetics. Type 1 diabetes, where the immune system destroys the cells that make insulin, represents the remaining 5 to 10% and typically appears in childhood or early adulthood, though it can develop at any age.
Age Makes a Major Difference
Diabetes rates climb sharply with age. Among adults 65 and older, 28.8% have diabetes, nearly 1 in 3. That’s a dramatic jump compared to younger adults and reflects decades of gradual decline in the body’s ability to regulate blood sugar, compounded by weight gain and reduced physical activity over time.
Prediabetes follows a similar pattern. About 36% of adults aged 18 to 44 already have prediabetes, meaning their blood sugar is elevated but not yet in the diabetic range. That number rises to nearly 49% among adults 45 to 64, and crosses 52% in adults 65 and older. When you combine diabetes and prediabetes in the senior population, the majority of older Americans have some form of blood sugar dysregulation.
Prediabetes: The Larger Hidden Problem
The 12% figure for diabetes is striking on its own, but the broader picture is more alarming. Tens of millions of additional Americans have prediabetes, a condition where blood sugar is elevated enough to cause damage but hasn’t crossed the diagnostic line for diabetes. Most people with prediabetes have no symptoms and are unaware of their status.
Prediabetes is not a guaranteed path to diabetes. With changes to diet, exercise, and body weight, many people can bring their blood sugar back into a normal range. Losing just 5 to 7% of body weight, roughly 10 to 14 pounds for someone who weighs 200, significantly lowers the risk of progression. Without those changes, prediabetes converts to type 2 diabetes at a rate of about 5 to 10% per year.
Why the Numbers Keep Growing
Diabetes prevalence in the U.S. has risen substantially over the past two decades. Several forces are driving the increase simultaneously. Obesity rates have climbed, and excess body fat, particularly around the midsection, is the single strongest modifiable risk factor for type 2 diabetes. The population is also aging, which pushes more people into higher-risk age brackets. Improved screening has likely contributed too, catching cases that would have gone undetected in earlier decades.
The 12% prevalence figure today represents a condition that affects every corner of American life: workplace productivity, healthcare costs, and quality of life for millions of families. Diabetes remains one of the top 10 leading causes of death in the U.S. and the primary driver of kidney failure, lower-limb amputations, and adult-onset blindness.