Ethnic differences in cross‐sectional associations between impaired glucose regulation, identified by oral glucose tolerance test or HbA_1c values, and cardiovascular disease in a cohort of European and South Asian origin

Abstract

AimsWe contrasted impaired glucose regulation (prediabetes) prevalence, defined according to oral glucose tolerance test or HbA1c values, and studied cross‐sectional associations between prediabetes and subclinical/clinical cardiovascular disease (CVD) in a cohort of European and South Asian origin.MethodsFor 682 European and 520 South Asian men and women, aged 58–85 years, glycaemic status was determined by oral glucose tolerance test or HbA1c thresholds. Questionnaires, record review, coronary artery calcification scores and cerebral magnetic resonance imaging established clinical plus subclinical coronary heart and cerebrovascular disease.ResultsPrediabetes was more prevalent in South Asian participants when defined by HbA1c rather than by oral glucose tolerance test criteria. Accounting for age, sex, smoking, systolic blood pressure, triglycerides and waist–hip ratio, prediabetes was associated with coronary heart disease and cerebrovascular disease in European participants, most obviously when defined by HbA1c rather than by oral glucose tolerance test [odds ratios for HbA1c‐defined prediabetes 1.60 (95% CI 1.07, 2.39) for coronary heart disease and 1.57 (95% CI 1.00, 2.51) for cerebrovascular disease]. By contrast, non‐significant associations were present between oral glucose tolerance test‐defined prediabetes only and coronary heart disease [odds ratio 1.41 (95% CI 0.84, 2.36)] and HbA1c‐defined prediabetes only and cerebrovascular disease [odds ratio 1.39 (95% CI 0.69, 2.78)] in South Asian participants. Prediabetes defined by HbA1c or oral glucose tolerance test criteria was associated with cardiovascular disease (defined as coronary heart and/or cerebrovascular disease) in Europeans [odds ratio 1.95 (95% CI 1.31, 2.91) for HbA1c prediabetes criteria] but not in South Asian participants [odds ratio 1.00 (95% CI 0.62, 2.66); ethnicity interaction P = 0.04].ConclusionsPrediabetes appeared to be less associated with cardiovascular disease in the South Asian than in the European group. These findings have implications for screening, and early cardiovascular prevention strategies in South Asian populations.

Low concordance between HbA1c and OGTT to diagnose prediabetes and diabetes in overweight or obesity

“…It should be considered that HbA1c levels in subjects with impaired glucose tolerance or T2D and its relationship with cardiovascular risk might differ by race and ethnicity, as reported by Eastwood et al This finding may be affected, almost in part, by genetic traits influencing erythrocyte turnover, or alternatively, by nutritional or metabolic factors. Accordingly, some studies showed an increase in the prevalence of subjects with pre‐T2D diagnosed by HbA1c test, whereas others reported a decreased prevalence of subjects with pre‐T2D compared to that obtained according to the OGTT criteria . As suggested by Kanat et al the two tests may highlight different aspects of dysglycaemia and identify different subjects with glucose intolerance.…”

“…It should be con- TA B L E 3 Cardiovascular risk factors in subjects with overweight/obesity according to the positivity to the different tests profile. 8,11 Conversely, several prospective data suggest that a significant percentage of subjects developing T2D did not present an altered OGTT. 12 It could therefore exist in the group with normal OGTT, a subgroup at higher risk that the HbA1c test could help to identify.…”

Utility of HbA1c and fasting plasma glucose for screening of Type 2 diabetes: a meta‐analysis of full ROC curves

“…For sensitivity analyses, we estimated the SROC curves separately for Asian and non‐Asian countries because we assume that different genetic factors influence the diagnostic test threshold . The complete results are given Table .…”

Noncommunicable disease in rural India: Are we seriously underestimating the risk? The Nallampatti noncommunicable disease study

“…[14] It is unclear at this point whether the greater prevalence of HbA1c defined prediabetes in Asian Indian population translates into cardiovascular risk with some studies from the United Kingdom suggesting that prediabetes defined by HbA1c in South Asian population showed significantly weaker associations with cardiovascular risks compared to western counterparts. [1516]…”