Background: Non-communicable diseases (NCDs), also known as chronic diseases, now constitute a major proportion of ill-health across most adult and older populations including in people with intellectual disability. The current paper is a comparative analysis of prevalence of NCDs across mid-aged and older-aged people with mild intellectual disability. Method: Comparative data comes from two cross-sectional surveys using similar methodology and timeframes. The analysis sample comprises mid-aged group (30-50 years, N = 291) and older-aged group (=60 years, N = 391). Results: People with mild intellectual disability start developing NCDs in early to mid-adulthood and increases with age. The mean number of NCDs in mid-aged group was 0.86 (SD, 0.84) compared to 3.82 in older group (SD, 2.67). Conclusion: There needs to be early identification and management of NCDs using relevant health promotion and preventative measures at optimal intervention points. The training of healthcare professionals needs improvement.