Comparison of mortality in people with type 2 diabetes between different ethnic groups: systematic review and meta-analysis of longitudinal studies

People of South Asian and Black ethnicity have a higher prevalence of type 2 diabetes (T2D) compared to people of White ethnicity. T2D is a leading cause of mortality worldwide, however, rigorous investigation including the most recent studies comparing mortality in different ethnic groups has not been conducted. This systematic review and meta-analysis aim to compare mortality risk in people with T2D between different ethnic groups. This systematic review follows PRISMA guidelines (PROSPERO:CRD42022372542). Nine databases were searched for community-based studies among T2D adults from ≥2 ethnicities. Studies published between January, 2000 and May, 2024 and containing ≥100 participants in each reported ethnic group were included. Two independent reviewers undertook title/abstract and full-text screening, data extraction, quality assessment (using Newcastle-Ottawa Scale) and data synthesis with group consensus to resolve any conflicts. The primary outcome compared all-cause mortality rates between ethnic groups (hazard ratio [HR] with 95% confidence intervals). From 33 922 records screened, 13 studies met inclusion criteria and 7 were meta-analysed. The 13 studies incorporated 593 058 T2D participants and 12/13 were of good quality. Overall mortality risk was lower amongst people with T2D from South Asian (HR 0·68 [95% CI 0·65–0·72]; 4 studies), Black (0·82 (0·77–0·87]; 5 studies) and Chinese (0·57 [0·46–0·70]; 2 studies) ethnicity compared to people of White ethnicity. Narrative synthesis corroborated quantitative findings and highlighted that people of indigenous Māori ethnicity had greater mortality risk compared to people of European ethnicity. People with T2D of South Asian, Black and Chinese ethnicity have a lower risk of all-cause mortality compared to those of White ethnicity, whilst Māori ethnicity have higher mortality risk. Risk factors or clinical management could explain differences in T2D mortality risk especially when comparing T2D complications by ethnicity, thus need further scrutiny to improve overall diabetes outcomes. No funding was received.