Background Endothelial dysfunction is an early feature of vascular disease. Left ventricular (LV) diastolic reserve is the ability of the left ventricle to augment diastolic function with exercise and may be impaired in patients with diabetes mellitus (DM). It is unclear if endothelial dysfunction is related to impaired LV diastolic reserve and diminished exercise capacity.

Methods 96 patients with type 2 DM and 10 controls had brachial artery reactivity testing, followed by exercise echocardiography. The brachial artery diameter was measured at rest and during reactive hyperaemia. LV diastolic reserve was measured as Δe′ with exercise and diastolic reserve index (Δe′/rest e′). Exercise capacity was calculated by metabolic equivalents (METs).

Results Compared with controls, patients with DM had lower rest e′ (7 vs 9 cm/s, p=0.002), lower Δe′(1 vs 4 cm/s, p=0.023), lower Δe′/rest e′ (0.20 vs 0.47, p=0.003) and reduced flow mediated dilation (FMD, 5 vs 15%, p<0.001). FMD was correlated with Δe′ (r=0.65, p<0.001), diastolic reserve index (r=0.61, p<0.001) and post-exercise septal E/e′ (r=−0.50, p<0.001), but not with rest e′ (r=0.13, p=0.177). FMD was an independent predictor of Δe′ (β=0.002, p<0.001, R²=0.47) and diastolic reserve index (β=0.030, p<0.001, R²=0.41). Younger age (p<0.001), male gender (p=0.014), lower body mass index (p<0.001), lower rest E/e′ (p=0.042) and higher FMD (p=0.025) were independent predictors of higher METs (R²=0.52, p<0.001).

Conclusions Patients with DM had impaired endothelial function and LV diastolic dysfunction. LV diastolic reserve and exercise capacity are linked to endothelial function. Targeting vascular risk factors to improve endothelial function may improve LV diastolic reserve and exercise capacity.