Picture a classroom of thirty teenagers. Statistically, according to a study published on February 25, 2026, ten of those children are walking around right now with blood sugar levels in the prediabetes or type 2 diabetes range. Most of them have no symptoms. Neither they nor their parents have any idea. That is not a worst-case scenario. That is the current national average, drawn from the federal government’s own data.
A new analysis of the National Health and Nutrition Examination Survey (NHANES), covering 1,998 adolescents aged 10 to 19 years from 2021 through 2023, found that 30.8% of American teenagers (nearly one in three) met the laboratory criteria for prediabetes or type 2 diabetes. The definition used was straightforward and conservative: a hemoglobin A1c of 5.7% or higher, or a fasting plasma glucose of 100 mg/dL or higher. These are the same thresholds used by every major diabetes organization in the country.
Let that sink in. Not one in ten. Not one in five. One in three!
When NHANES last examined a comparable group two decades ago, the figure was approximately 9%. The number has more than tripled in a generation. If that trajectory continues, the diabetes-related complications we now associate with middle age (kidney disease, cardiovascular disease, nerve damage, blindness) will arrive far earlier in the lives of millions of Americans who are today in middle school.
The good news, and it is critical that you hear this clearly: prediabetes is reversible. When caught early and addressed aggressively, the metabolic clock can be turned back. But you cannot reverse what you do not know is there. And right now, most parents do not know.
The Measurement Your Doctor Is Almost Certainly Not Taking
Here is where the study becomes genuinely startling, not just for its prevalence numbers, but for what it reveals about the inadequacy of how we currently assess risk in children.
Body mass index (BMI) is the standard tool pediatricians use to flag weight-related health concerns. You have almost certainly heard your child’s BMI discussed at a well-child visit. The problem, according to this new research, is that BMI is the wrong tool for identifying prediabetes risk.
When the researchers ran their statistical models adjusting for all the relevant variables simultaneously, BMI lost its significance entirely. It was no longer a meaningful predictor of prediabetes. What remained, and remained with extraordinary force, was waist-to-height ratio, a simple measurement that takes about thirty seconds with a tape measure and requires no laboratory equipment whatsoever.
Adolescents with an elevated waist-to-height ratio had 146 times the odds of having prediabetes or type 2 diabetes compared to those without it (adjusted odds ratio 146.19; 95% CI: 5.39 to 3,976; p = 0.004). This is not a modest association. This is an overwhelming one. Waist-to-height ratio not only outperforms BMI in this analysis; it essentially replaces it.
The reason matters. BMI measures overall body mass relative to height. Waist-to-height ratio measures central adiposity (the accumulation of fat around the abdomen and internal organs). It is visceral fat, not subcutaneous fat, that drives insulin resistance, inflammation, and metabolic disease. A teenager can have a technically normal BMI while carrying dangerous amounts of fat around the organs, and a standard pediatric visit will miss it entirely.
This finding is consistent with a growing body of evidence. Brambilla and colleagues demonstrated that the waist-to-height ratio explained 64% of the variance in% body fat among children and adolescents, compared to only 32% for BMI. That predictive power increased to 80% after adjusting for age and sex. We have known for years that this measurement is superior. What this new study adds is the direct link to prediabetes risk in a nationally representative American sample, with an odds ratio so large it should prompt an immediate rethinking of routine pediatric screening.
Boys Are at Far Greater Risk Than Girls
The second major finding of this study is the dramatic sex disparity in risk. Of the adolescents identified with prediabetes or type 2 diabetes, 62% were male, and 38% were female. After adjusting for all other variables, being female was independently associated with roughly half the odds of having the condition (adjusted odds ratio 0.52; 95% CI: 0.36 to 0.78).
This is not a statistical artifact. The biological underpinnings are well established. Adolescent males tend to accumulate more visceral fat during puberty than females, and androgens (the male sex hormones surging during this developmental period) independently drive insulin resistance. If you are the parent of a teenage boy, the numbers in this study apply to your son with particular force.
Younger age was also associated with a higher risk, meaning the problem is not confined to older teenagers. Early adolescents aged 10 to 14 appear at least as vulnerable as their older peers.
The 30-Second Test You Can Do Tonight
You do not need a laboratory, a specialist, or an expensive screening to get a first read on your child’s risk. You need a tape measure.
Measure your child’s waist circumference at the level of the navel (the belly button) while they are standing relaxed and breathing normally. Write down that number in inches. Then measure their height in inches. Divide the waist number by the height number.
If the result is less than 0.5, their waist-to-height ratio is in the healthy range. If it is 0.5 or greater, they have abdominal obesity by the research definition used in this study, and their risk of prediabetes, already elevated in the general population of teenagers, climbs steeply.
As a practical example: a 5’4” teenager (64 inches tall) with a 33-inch waist has a waist-to-height ratio of 0.516, placing them in the elevated-risk category. That same teenager with a 31-inch waist has a ratio of 0.484, placing them in the healthy range. The difference is two inches of waist circumference. This is a measurement worth taking.
This is a screening tool, not a diagnosis. An elevated waist-to-height ratio tells you that a conversation with your physician and appropriate laboratory testing are warranted. It does not tell you that your child has diabetes. But it tells you something a BMI number may not: where fat is being stored, and whether that pattern places your child at metabolic risk.
Five Steps to Take Right Now
1. Ask for the right laboratory tests
At your child’s next well-visit, or sooner if their waist-to-height ratio is elevated, ask specifically for a fasting plasma glucose and a hemoglobin A1c. These are the two tests used in this study and by the American Diabetes Association to define prediabetes. Do not assume they are automatically ordered. In many pediatric practices, they are not, unless the physician has a specific concern about diabetes risk. You may need to be the one who raises it.
2. Reduce liquid sugar and ultra-processed carbohydrates
While this study found that dietary variables did not persist as independent predictors of prediabetes after adjusting for body fat distribution, that does not mean diet is irrelevant; it means that diet’s effect on prediabetes risk operates largely through its effect on fat accumulation, particularly visceral fat. Sugar-sweetened beverages (sodas, sports drinks, fruit juices, flavored coffees, energy drinks) are the single most efficient way to drive central adiposity in adolescents. Eliminating them is the highest-leverage dietary change a family can make.
3. Prioritize resistance training over cardio alone
Aerobic exercise improves cardiovascular fitness. Resistance training (lifting weights, bodyweight exercises, resistance bands) builds skeletal muscle, and skeletal muscle is the primary site of glucose disposal in the body. More muscle means more capacity to clear blood sugar from the circulation. Teenagers who engage in regular resistance training are building metabolic infrastructure that will serve them for decades. Aim for two to three sessions per week of progressive resistance work, in addition to general physical activity.
4. Address screen time as a metabolic issue, not just a behavioral one
In this study, 88.5% of adolescents spent two or more hours per day in sedentary screen-based activity. Sedentary behavior did not independently predict prediabetes in the multivariate model, because its effect operates through fat accumulation and the displacement of physical activity. But that is precisely the point. Hours spent motionless in front of a screen are hours not spent moving, and the metabolic cost accumulates silently. The target should be no more than 2 hours of recreational screen time per day, with physical breaks built into longer periods of sitting.
5. Make the waist-to-height ratio a routine household measurement
Annual or semi-annual measurement of the waist-to-height ratio costs nothing and takes thirty seconds. It gives you information that a bathroom scale and a BMI chart do not. A child’s weight can remain stable while their waist-to-height ratio climbs, a sign that fat is redistributing from subcutaneous to visceral depots, even at a constant total body weight. Tracking this number over time provides an early warning system that no standard pediatric metric currently offers.
The Window Is Open, But It Will Not Stay Open
Prediabetes in a teenager is not a life sentence. The pancreatic beta cells are not yet destroyed. Insulin sensitivity can be restored. The metabolic trajectory can be reversed. Research consistently shows that lifestyle intervention (not medication, not surgery, but real changes to how we eat, move, and sleep) is the most powerful tool available for preventing the progression from prediabetes to type 2 diabetes.
But the window for intervention is not infinite. Youth-onset type 2 diabetes is more aggressive than adult-onset disease. Complications arrive earlier. The beta cells deplete faster. The longer prediabetes goes undetected and unaddressed in an adolescent, the more difficult reversal becomes, and the more likely complications are to materialize before the age of thirty.
One in three. That is the number we are living with right now. It is not acceptable, and it is not inevitable. What it is, is knowable, if we are willing to look. Get a tape measure. Ask for the lab work. And take this seriously, because the data leave no room for reassurance that everything is probably fine.
