Is Obesity a Universal Phenotype in Children with Type 2 Diabetes?
What is the global prevalence of obesity in children and adolescents suffering from type 2 diabetes mellitus (T2DM)? Does the occurrence of obesity in pediatric T2DM correlate with gender or race? And how is obesity in T2DM under 18 years of age associated with glycemic control and dyslipidemia? These questions have been addressed by Canadian authors in their recently published systematic review and meta-analysis, which deals with various issues related to childhood obesity.
The Challenge – Unknown Prevalence of Obesity in Children with T2DM
Pediatric obesity is a serious health problem and is still globally on the rise. In children and adolescents, similar to adults, obesity is associated with a higher risk of developing type 2 diabetes and often increased cardiovascular (CV) risk. In children, T2DM represents an aggressive disease, whose treatment often fails, leading to early comorbidities and complications, including non-alcoholic fatty liver disease (NAFLD), dyslipidemia, polycystic ovary syndrome, and nephropathy.
The complex factors in the pathogenesis of T2DM development before 18 years of age are not fully defined, and the unknown prevalence of obesity in the pediatric population with T2DM remains a primary issue. The authors of the cited work highlight that only obese children are typically screened and subsequently diagnosed with T2DM. If obesity is not a universal phenotype of this disease, children with body weight within the reference range may have T2DM caused by other factors than obesity. This could affect the treatment and its outcomes. Estimating the prevalence of obesity in the T2DM pediatric population could significantly impact screening recommendations for this disease.
Evaluated Studies and Analyzed Parameters
The aim of the systematic review and meta-analysis was to evaluate the global prevalence of obesity in children and adolescents with T2DM and assess any association of obesity within this population with gender and race. Additionally, the study evaluated the association of obesity with T2DM-related metabolic profile, including glycemic control and lipid homeostasis. For this purpose, the authors used information from studies published in the databases MEDLINE, Embase, CINAHL, Cochrane Library, and Web of Science up to June 16, 2022. Observational studies investigating the prevalence of obesity in pediatric T2DM patients, which included at least 10 participants, were selected. Following the recommended procedure for meta-analyses of observational studies in epidemiology, two independent reviewers extracted data, assessed the risk of bias, and rated the evidence level. The meta-analysis was conceived using a random-effects model.
The primary parameter was the combined prevalence of obesity in children with T2DM. Secondary parameters included the combined prevalence of obesity by gender and race and the relationship between obesity, glycemic control, and dyslipidemia.
Findings
Fifty-three studies with a total of 8942 participants were included in the final meta-analysis:
- The overall prevalence of obesity among pediatric patients with type 2 diabetes was 75.27% (95% confidence interval [CI] 70.47–79.78%), and the prevalence of obesity at the time of T2DM diagnosis (in 4688 participants from 30 studies) was 77.24% (95% CI 70.55–83.34%).
- Boys with T2DM had a higher prevalence of obesity (78.65%) than girls with T2DM (59.2%, odds ratio [OR] 2.10; 95% CI 1.33–3.31).
- From an ethnic perspective, Asian children and adolescents with T2DM had the lowest prevalence of obesity (64.50%; 95% CI 53.28–74.99%), while the highest prevalence of obesity was observed in the white pediatric population with T2DM (89.86%; 95% CI 71.50–99.74%).
- The reported prevalence of overweight varied from 0–43.4%.
- A wide heterogeneity across studies was found in the assessment of glycemic control and dyslipidemia. The HbA1c level ranged from 4.5 to 12.6% (25.7–114.2 mmol/mol), and a meta-regression analysis did not show a significant correlation between obesity and HbA1c levels. The prevalence of dyslipidemia across 31 studies was 4.0–87.5%. In the meta-regression analysis, an association was found between obesity and low HDL cholesterol levels.
Conclusion and Discussion
The authors concluded that according to the systematic review and meta-analysis, obesity is not a universal phenotype in children with type 2 diabetes. They emphasized the need for further studies to elucidate the potential role of obesity and other mechanisms in the pathogenesis of T2DM in the pediatric population. “Although obesity was an important risk factor for T2DM development in children in this study, it was not present in all T2DM patients. From the perspective of T2DM screening and diagnosis, obesity can be considered a risk factor but not a prerequisite for screening if other risk factors are present. Understanding the causes of T2DM in non-obese children is crucial for defining the etiology of their diabetes and developing effective management strategies for this cohort. Further research is needed to evaluate the gender, race, and ethnicity associations of diabetes with obesity and to explore other factors that may influence the risk of T2DM development in children,” they concluded.
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Source: Cioana M., Deng J., Nadarajah A. et al. The prevalence of obesity among children with type 2 diabetes: a systematic review and meta-analysis. JAMA Netw Open 2022 Dec 1; 5 (12): e2247186, doi: 10.1001/jamanetworkopen.2022.47186.
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