Ethnic disparities in the association of impaired fasting glucose with the 10-year cumulative incidence of type 2 diabetes

Evidence of ethnic disparities in the conversion of prediabetes to type 2 diabetes is scarce. We studied the association of impaired fasting glucose (IFG) and fasting plasma glucose (FPG) with the 10-year cumulative incidence of type 2 diabetes in three ethnic groups. We analyzed data for 90 South-Asian Surinamese, 190 African-Surinamese, and 176 ethnic Dutch that were collected in the periods 2001-2003 and 2011-2012. We excluded those with type 2 diabetes or missing FPG data. We defined baseline IFG as FPG of 5.7-6.9 mmol/L. We defined type 2 diabetes at follow-up as FPG ≥ 7.0 mmol/L, HbA1c ≥ 48 mmol/mol (6.5%), or self-reported type 2 diabetes. 10-Year cumulative incidences of type 2 diabetes were: South-Asian Surinamese, 18.9%; African-Surinamese, 13.7%; ethnic Dutch, 4.5% (p <0.05). The adjusted association of baseline IFG and FPG with the 10-year cumulative incidence of type 2 diabetes was stronger for South-Asian Surinamese than for African-Surinamese and ethnic Dutch. The IFG (compared to normoglycaemia) ORs were 11.1 [3.0-40.8] for South-Asian Surinamese, 5.1 [2.0-13.3] for African-Surinamese, and 2.2 [0.5-10.1] for ethnic Dutch. The 10-year cumulative incidence of type 2 diabetes was higher and associations with baseline IFG and FPG were stronger among South-Asian Surinamese and African-Surinamese than among ethnic Dutch. Our findings confirm the high risk of type 2 diabetes in South-Asians and suggest more rapid conversion in populations of South-Asian origin and (to a lesser extent) African origin than European origin