Fasting plasma glucose and variation in cardiometabolic risk factors in people with high-risk HbA1c-defined...

Variation in cardiometabolic risk in prediabetes and any impacts of ethnicity on such variation have been little studied. In an ethnically diverse dataset, selected according to a high-risk HbA1c-based definition of prediabetes, we have investigated relationships between glycaemia and cardiometabolic risk factors and the influence of ethnicity on these relationships.

We undertook a cross-sectional analysis of baseline data from a diabetes prevention study in the UK and a chronic care clinic in Thailand, selected for people without diabetes (fasting plasma glucose <7.0 mmol/l) with HbA1c 6.0-6.4% (42-47 mmol/mol). Thai (n=158) and UK White (n=600), South Asian (n=112), Black (n=70) and other/mixed (n=103) groups were distinguished and measurements included fasting plasma glucose (FPG), blood pressure (BP), lipids and insulin resistance-related risk factors (IRFs).

Independently of individual characteristics including ethnicity, only systolic BP was weakly associated with FPG (beta coefficient 1.76 (95%CI 0.10-3.42), p 0.03) and only LDL-c with IFG (FPG 5.6 to <7) (adjusted -0.14 (-0.27, -0.003) p 0.04). There were no significant independent associations with cardiometabolic risk factors when categories of impaired fasting glucose (FPG ≥ 6.1 to <7.0 mmol/L) were considered. Relative to White, South Asian ethnicity was independently associated with lower systolic and diastolic BP, Black with lower triglycerides, cholesterol/HDL-c ratio and having 2 or more IRFs, and Thai with lower cholesterol/HDL-c ratio and all three non-white ethnicities with lower total and LDL cholesterol.

In high-risk HbA1c-defined prediabetes additional measurement of FPG will add little to evaluation of cardiometabolic risk. Additionally, UK Whites tend to have the most adverse cardiometabolic profile of any ethnic group.