A study of 802 teens raises questions about school breakfast and blood sugar

by · News-Medical

Could school breakfast habits reveal something about teenage metabolic health? Researchers examine how school meals, everyday food choices, and obesity relate to early signs of impaired glucose regulation.

Study: School Meal Participation, Overall Dietary Intake, and Prediabetes Prevalence Among U.S. Adolescents: Insights From the National Health and Nutrition Examination Survey (2017–2023). Image Credit: New Africa / Shutterstock

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In a recent cross-sectional study published in the journal Diabetes, Obesity, and CardioMetabolic CARE, researchers investigated associations between school meal participation, dietary intake, and prediabetes prevalence among American adolescents.

The team analyzed data from 802 adolescents (ages 12 to 18 years) enrolled in the National Health and Nutrition Examination Survey (NHANES; 2017-2023 survey cycles) to examine relationships between school nutrition programs, dietary factors, and markers of impaired glucose regulation.

School breakfast participation (at least once per week) was associated with a 30% higher prediabetes prevalence compared with nonparticipation. The association was no longer statistically significant after correction for multiple comparisons. School lunch participation showed no statistically significant relationship with adolescent prediabetes.

Background

Prediabetes is increasingly recognized among adolescents, whose diet, physical activity, and sleep habits may affect metabolic health.

Recent national estimates from the United States (US) indicate that approximately 33% of adolescents aged 12 to 17 years had prediabetes in 2023.

Adolescence is a metabolically vulnerable period characterized by transient physiological insulin resistance as hormonal changes during puberty temporarily reduce cellular sensitivity to insulin. Poor dietary quality may also contribute to impaired glucose regulation and later type 2 diabetes risk.

Schools provide around half of daily calories for many school-aged children, particularly those from lower-income households, making institutional meal quality a public health concern. School menus may also feature ultra-processed foods (UPFs) and nutrient-poor items, prompting questions about their possible metabolic effects.

Previous research has often relied on older datasets or overlooked whether dietary associations vary by obesity status, leaving limited recent evidence on school meal participation, overall diet, and prediabetes prevalence.

About the study

To investigate these relationships, the researchers examined associations between school meal consumption, overall nutrient intake, and laboratory markers of prediabetes among adolescents.

The researchers pooled nationally representative data from the 2017–2020 and 2021–2023 NHANES waves. The adolescents had a mean age of 14.5 years; approximately half were male, and all had complete fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) measurements.

The study compared adolescents with normal-range and prediabetes-range laboratory results after excluding those with reported diabetes or laboratory values in the diabetes range, based on the American Diabetes Association (ADA) criteria.

Prediabetes-range results included an impaired FPG of 100 to 125 mg/dL, an HbA1c of 5.7% to 6.4%, or both. Because classification relied on a single assessment, these results indicate laboratory values within the prediabetes range rather than a clinical diagnosis.

The researchers examined school breakfast and lunch participation (none versus at least once weekly), along with overall dietary intake assessed through two 24-hour recalls. The dietary assessment covered major food groups and nutrients, including carbohydrates, total sugars, dietary fiber, different types of fat, and selected vitamins.

The researchers used survey-weighted statistical models to assess associations, accounting for demographic and socioeconomic characteristics. Additional adjustments considered energy intake, physical activity, or school meal participation, depending on the analysis.

The analysis also assessed whether the associations differed by obesity status, defined as a body mass index (BMI) at or above the age- and sex-specific 95th percentile.

Study findings

The analysis found that 33.8% of adolescents had laboratory results within the prediabetes range, while 20.96% had obesity. After multivariable adjustment, participation in school breakfast at least once weekly was associated with a 30% higher prevalence of prediabetes-range laboratory results than nonparticipation. Nonparticipation in school breakfast did not necessarily mean that adolescents skipped breakfast altogether.

Sensitivity analyses suggested that sporadic breakfast participation (1 to 3 days weekly) was associated with the highest relative prediabetes prevalence, while participation on 4 to 5 days showed no statistically significant association.

The analysis found no statistically significant association between school lunch participation and prediabetes. In initial analyses, higher intakes of vitamin E and vitamin B6 were each associated with lower prediabetes prevalence. Total sugar intake was not significantly associated with prediabetes, and the researchers could not assess added sugar consumption separately.

Higher fruit consumption was associated with lower prediabetes prevalence only among adolescents with obesity. Across the analyses, none of the reported associations remained statistically significant after correction for multiple comparisons.

Conclusions

The findings suggest that school breakfast quality warrants further investigation as a possible factor in adolescent metabolic health, alongside the dietary factors examined.

The authors hypothesize that morning school offerings may contain more added sugars, juice, and ultra-processed foods than lunch menus, but the study did not directly assess school meal composition. They recommend that future school nutrition policies consider balanced, nutrient-dense breakfast options, while their effects on metabolic health remain uncertain.

The cross-sectional design, reliance on self-reported dietary data, possible unmeasured confounding, and pandemic-related disruptions to school meals limit interpretation. The findings do not show that school breakfast causes prediabetes. Longitudinal and intervention studies are needed to establish whether improving school meal quality influences adolescent metabolic outcomes.

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