Long-Term Cardiometabolic Outcomes in Children With Metabolically Healthy and Unhealthy Obesity.

Importance: Metabolically healthy obesity (MHO) in children has been considered a low-risk phenotype, potentially not requiring treatment. However, their long-term cardiometabolic outcomes remain unclear. Objective: To compare the occurrence of type 2 diabetes, hypertension, dyslipidemia, and mortality up to young adulthood in children with metabolically healthy obesity (MHO), metabolically unhealthy obesity (MUO), and general population peers, and to investigate the association between obesity treatment response and disease risk. Design, Setting, and Participants: This was a prospective cohort study including children undergoing obesity treatment recorded in the Swedish Childhood Obesity Treatment Register (BORIS) between 1997 and 2020 and their general population comparators, linked with national registers. Children in the cohort with obesity were aged 7 to 17 years at obesity treatment initiation and had complete cardiometabolic data. General population comparators were matched (ratio 1:5) based on sex, birth year, and residential area. Study data were analyzed from February to March 2025. Exposures: Exposures included metabolically healthy obesity (MHO), defined as the absence of high blood pressure, impaired fasting glycemia, elevated transaminases, elevated triglycerides, and low high-density lipoprotein cholesterol; otherwise, children were categorized as having metabolically unhealthy obesity (MUO). Main Outcomes and Measures: Type 2 diabetes, hypertension, dyslipidemia, and mortality up to age 30 years. Results: A total of 7275 children (median [first quartile {Q1}-third quartile {Q3}] age, 11.1 [9.1-13.5] years; 4004 male [55.0%]) were included, along with 35 636 general population comparators (median [Q1-Q3] age, 11.1 [9.1-13.5] years; 19 596 male [55.0%]). MHO at baseline was present in 3626 children (49.8%; median [Q1-Q3] age, 10.6 [8.8-12.8] years; 1981 male [54.6%]), and MUO was present in 3649 children (50.2%; median [Q1-Q3] age, 11.6 [9.4-14.0] years; 2023 male [55.4%]). By age 30 years, cumulative incidences were as follows: type 2 diabetes (MHO, 9.1%; MUO, 16.8%; general population, 0.5%), hypertension (MHO, 10.8%; MUO, 18.3%; general population, 3.7%), and dyslipidemia (MHO, 5.3%; MUO, 12.7%; general population, 0.9%). A reduction of at least 0.25 body mass index (BMI) z score was associated with reduced incidence rate ratio (IRR) of type 2 diabetes (IRR, 0.22; 95% CI, 0.14-0.35), hypertension (IRR, 0.56; 95% CI, 0.34-0.93), and dyslipidemia (IRR, 0.28; 95% CI, 0.14-0.57), with similar risk reduction for MHO and MUO. Conclusions and Relevance: Results of this cohort study reveal that a reduction in BMI z score of at least 0.25 was associated with similar risk reductions for both MHO and MUO. Children with MHO face a substantially increased cardiometabolic disease risk already as young adults compared with the general population. Hence, obesity treatment should be recommended for all children with obesity, regardless of initial metabolic status.