Nearly one in three American teenagers already has prediabetes or type 2 diabetes, according to a new study analyzing federal health data.
Researchers reviewed data from the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey between 2021 and 2023. They found that 30.8% of adolescents ages 10 to 19 had blood sugar levels in the prediabetes or type 2 diabetes range.
The findings were published in PLOS Global Public Health.
The vast majority of cases were prediabetes. Only five out of 1,998 teens studied had confirmed type 2 diabetes.
But health experts warn that prediabetes in teenagers is serious. It means blood sugar levels are higher than normal but not yet high enough for a diabetes diagnosis. Left untreated, it often progresses to full type 2 diabetes.
Type 2 diabetes in young people tends to move faster than in adults. It can lead to kidney damage, nerve problems, and vision loss earlier in life.
The new study shows a sharp rise over the past two decades.
An earlier review of federal survey data from 1999 to 2002 found that about 9% of adolescents ages 12 to 19 had prediabetes or diabetes. Today, that number stands at nearly 31%.
Researchers attribute the increase to rising childhood obesity, sedentary behavior, and diets heavy in processed foods.
Among adolescents with elevated blood sugar, 62% were boys and 38% were girls.
Researchers suggest biological factors may play a role. Boys are more likely to accumulate visceral fat, which settles around internal organs and is more strongly linked to metabolic problems.
Younger adolescents also showed somewhat higher risk than older teens, a finding that surprised some clinicians.
One of the most significant findings involves how doctors screen for risk.
Body mass index, or BMI, has long been used to measure whether someone is overweight. But once researchers accounted for other measurements, BMI was no longer an independent predictor of prediabetes.
Instead, waist-to-height ratio proved to be a much stronger indicator.
This measurement divides waist circumference by height. A ratio of 0.5 or higher signals central obesity, meaning excess fat concentrated in the abdomen.
Teens with a waist-to-height ratio at or above 0.5 were 146 times more likely to have prediabetes or type 2 diabetes, according to the study. Researchers caution that the figure reflects a wide statistical range due to the small number of confirmed diabetes cases. Still, the overall pattern was clear.
About 40.8% of adolescents in the study met that central obesity threshold.
The study acknowledged that unhealthy habits likely contribute to fat accumulation and rising blood sugar.
Nearly 89% of teens reported spending two or more hours per day on screens. Only about 21% met recommended physical activity guidelines.
However, after adjusting for body composition, lifestyle factors such as sedentary time, physical activity, calorie intake, and sugar consumption did not remain independent predictors of prediabetes.
The study stated: “Interestingly, lifestyle and dietary variables, including sedentary behavior, physical activity, total energy intake, and sugar consumption, did not persist as independent predictors of prediabetes/T2DM after multivariate adjustment.”
“This finding contrasts with prevailing narratives linking the global rise in obesity to adverse lifestyle factors such as physical inactivity and the overconsumption of energy-dense, ultra-processed foods.”
Researchers suggest pediatricians begin measuring waist-to-height ratio during routine checkups.
The test takes less than a minute and may identify high-risk teens that BMI alone would miss.
The findings come as policymakers continue debating how to combat rising obesity rates.
The Trump administration previously reached an agreement with drug manufacturers Eli Lilly and Novo Nordisk to make certain weight-loss drugs more affordable.
Health and Human Services Secretary Robert F. Kennedy Jr. praised the move at the time as part of a broader effort to address obesity nationwide.
With nearly one in three American teens now showing early signs of metabolic disease, researchers say early detection and prevention may be more urgent than ever.