Diagnosis of hyperglycemia in a cohort of Brazilian subjects: fasting plasma glucose- and oral glucose tolerance test-based glycemic status are associated with different profiles of insulin sensitivity and insulin secretion

High rate of abnormal glucose tolerance in Brazilian individuals undergoing coronary angiography

INTRODUCTION

Undiagnosed hyperglycemia is common in high cardiovascular risk individuals, especially in those with coronary artery disease (CAD). There is no consensus about the optimal method for the screening of hyperglycemia in this population.

SUBJECTS AND METHODS

Five hundred and fourteen Brazilian individuals undergoing coronary angiography, without previously known diabetes mellitus (DM), had their glycemic status evaluated by both fasting plasma glucose (FPG) and HbA1c, being classified in normal (N), prediabetes (PD), and DM according to American Diabetes Association criteria. Concordance between both methods was assessed by Cohen's κ. Accuracy of FPG and HbA1c to diagnose CAD was evaluated as proof-of-concept.

RESULTS

Among individuals screened by FPG, 41.2% had PD and 6% had DM. Among those screened by HbA1c, 52.7% had PD and 12.7% had DM. Concordance for a positive screening of PD occurred in 125 individuals (κ = 0.084). Eighteen individuals had a concordant positive screening of DM (κ = 0.310). As a predictor of CAD, accuracy of FPG was 0.554 (p = 0.009) and of HbA1c 0.557 (p = 0.006).

CONCLUSION

a high frequency of hyperglycemia, between 47 and 65%, was found in individuals submitted to coronary angiography without previously known glucose disturbances, using FPG and HbA1c as screening methods respectively.HbA1c detected significantly more individuals with both PD and DM than FPG. Concordance between both methods is low. The question of which is the gold-standard method to diagnose hyperglycemia in this population is still open.

Individuals with prediabetes identified by HbA1c undergoing coronary angiography have worse cardiometabolic profile than those identified by fasting glucose

BACKGROUND

Type 2 diabetes mellitus has well known deleterious effects on coronary artery disease (CAD). The role of milder hyperglycemic states such as prediabetes (PD) on CAD is debatable. Glycated hemoglobin (HbA1c) has recently been advocated as a diagnostic tool for diabetes mellitus (DM) and PD. This study aims to assess the cardiometabolic risk profile and coronary lesions of patients with PD undergoing coronary angiography identified either by fasting plasma glucose (FPG) or HbA1c levels.

METHODS

We studied 514 individuals without previously known glucose disturbances. Their glycemic status was assessed by FPG and HbA1c (HPLC) and classified according to ADA guidelines, using each parameter independently, as having normal glucose tolerance (N), PD, or DM. CAD was defined as stenosis greater than 50% in one major coronary vessel or branch. Framingham score was calculated.

RESULTS

Subjects with PD had a similar frequency of CAD compared do N individuals by both FPG (61 vs. 59.3%) and HbA1c (55.4 vs 61.2%) (p non-significant for linear-by-linear association). PD individuals identified by FPG had worse HOMA2B (mean [95% CI] 65.4 [60.9-69.9] vs. 76.6 [71.4-81.9]) and HOMA2-IR (1.10 [0.98-1.22] vs. 0.80 [0.72-0.89]) when compared to N controls. PD individuals identified by HbA1c had higher frequency of Framingham risk above 20% (25.4 vs 11.8%), arterial hypertension (87.8 vs 72.6%), and dyslipidemia (83.8 vs 72%) compared to N individuals. PD associated with an increased number of coronary lesions only when diagnosed by HbA1c (median [interquartile interval] 2 [0-4] PD versus 1 [0-3.75] N, p = 0.03 for trend).

CONCLUSIONS

HbA1c was more effective than FPG in identifying individuals with PD associated with high cardiovascular risk profile in a sample of individuals undergoing coronary angiography.