Objectives. To compare the prevalence of diabetic complications in young-onset type 2 diabetes (T2DM) with type 1 diabetes (T1DM) patients and to examine the relationship between clinical or metabolic parameters with diabetic complications.Methodology. This is a retrospective, cross-sectional comparative study based on electronic medical records review. Young-onset T2DM patients were defined as those with disease onset before the age of 40 and T1DM patients were included. Data were collected on demographic and clinical parameters, cardiovascular risks factors, macrovascular and microvascular complications.Results. There were 194 young-onset T2DM and 45 T1DM subjects. Despite similar glycaemic profile, more subjects in the T2DM group had unfavourable cardiovascular risk factors and developed complications than the T1DM group (22 vs. 0%, p<0.001 for macrovascular, 68 vs.Ê 27%, p<0.001 for microvascular). After adjustment of the confounders including age, gender, disease duration, HbA1c, obesity, blood pressure and lipid levels; young-onset T2DM instead of T1DM, hypertension, raised HbA1c and longer disease duration were independently associated with occurrence of diabetic complications.Conclusion. Young-onset T2DM appeared to be a more aggressive disease compared to T1DM. An aggressive approach should be adopted in treating young-onset T2DM to optimise the cardiovascular risk factors and glycaemic control to prevent premature mortality and morbidity.