Clinical characteristics of paediatric-onset type 2 diabetes: a comparison by weight status in the Hong Kong childhood diabetes registry 2008 to 2023

Abstract Objectives Although obesity is a major risk factor for paediatric type 2 diabetes (T2DM), many Asian youths present without obesity. This phenotype remains under-recognised and poorly described. This study aimed to compare the clinical and metabolic characteristics of children newly diagnosed with T2DM, stratified by weight status, in Hong Kong. Methods We conducted a retrospective cross-sectional study using data from the Hong Kong Childhood Diabetes Registry (2008–2023). We compared the clinical and metabolic features of children with and without obesity who were newly diagnosed with T2DM. Results A total of 689 children (96 % Chinese) were included and 35 % were children without obesity. While age at diagnosis was similar between groups, children without obesity exhibited a higher prevalence of family history of T2DM (80.6 % vs. 67.5 %; p<0.0001), more frequent presentations of classical symptoms and diabetic ketoacidosis with or without hyperosmolar hyperglycaemia state (4.6 % vs. 1.6 %, p=0.0262), and higher HbA 1c and blood glucose levels at diagnosis, with lower HOMA-%B, suggesting greater β-cell dysfunction. Conversely children with obesity had higher insulin resistance. They also had higher prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), hypertension, hyperuricaemia, obstructive sleep apnoea, and polyendocrine metabolic ovarian syndrome (PMOS). Insulin therapy was more frequently required at diagnosis in children without obesity (16.3 % vs. 8 %, p=0.001). Conclusions These results highlight a distinct T2DM phenotype in Chinese children without obesity, marked by severe hyperglycaemia and a higher rate of insulin requirement at diagnosis. Increased clinical vigilance for this under-recognised group is warranted to optimise management at diagnosis, with long term outcomes to be address in future longitudinal studies.