Funding Acknowledgements Type of funding sources: None. Background Extensive coronary artery disease (CAD) is common in diabetes mellitus. This relation between the extent of CAD and prediabetes (pDM)is less well established. Purpose To explore whether non-diabetic hyperglycaemia, assessed by HbA1c, is associated with extent of angiographic CAD, independent of traditional cardiovascular risk factors. Methods Retrospective cohort analysis of consecutive patients, without known DM undergoing coronary angiography for stable angina, who were screened for hyperglycaemia over 18 months. HbA1c was measured; pre-diabetes was defined as HbA1c 5.7-6.4%.Extent of CAD was assessed using the SYNTAX score. Presence of CAD was defined as visually estimated ≥50% luminal obstruction in arteries ≥1.5 mm diameter. Age, BMI, risk factors for CAD, HbA1c, total and LDL-cholesterol were recorded. The pre-diabetes and normal groups were compared using Mann-Whitney test for continuous variables and chi-squared test for categorical variables. Multiple logistic and linear regressions were used to assess the effect variables on SYNTAX score. Spearman rank correlation was used to assess the relation between HbA1c and SYNTAX score. Results 1071 patients had angiograms done. 207 had DM, 19 had new diagnosis of DM and 181 missed the screening leaving 664 who had HbA1c measured. 51 poor quality angiograms were excluded from SYNTAX calculation. Data was analysed for 613 (306 normal, 307 pDM) patients. The patients with prediabetes were older, had higher prevalence of risk factors, BMI, fasting glucose and SYNTAX score. HbA1c (OR 2.07, 95% CI 1.32 to 3.25, p=0.002) and the presence of pDM (OR 1.89, 95% CI 1.32 to 2.69, p<0.001) independently predicted the presence of CAD. HbA1c (Coefficient 2.42, SE 1.09, p=0.027) and the presence of pDM (Coefficient 2.25, SE 0.92, p=0.015) independently predicted the SYNTAX score. The correlation between HbA1c and SYNTAX score was weak but significant (Spearman's coefficient 0.206, 95% CI 0.129 to 0.281, p<0.0001). Conclusion HbA1c predicts the extent of CAD as measured by SYNTAX score in patients without known diabetes. Presence of pre-diabetes is an independent predictor of extent of CAD.

LV LA bpm Figure 1. Transthoracic echocardiogram in para-sternal long axis showing coaptation deficit of the mitral valve. LA: left atrium, LV: left ventricle.

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