Cardiac dysfunction in type II diabetes: a bittersweet, weighty problem, or both?

AIMS: Weight loss in obese patients leads to improved left ventricular (LV) function. It is unclear whether improving glycaemic control has additional benefits to weight loss alone in patients with type 2 diabetes, or if benefits of weight loss are mediated through improving glycaemic control. This case-control study examined the incremental impact of these approaches on LV function. METHODS: Three groups of age, gender, and baseline HbA1c-matched patients with type 2 diabetes and suboptimal glycaemic control were followed-up for 12 months. Group 1 patients did not improve HbA1c ≥ 1 % (10.9 mmol/mol) or lose weight. Group 2 improved HbA1c ≥ 1 % but did not lose weight. Group 3 improved HbA1c ≥ 1 % (10.9 mmol/mol) and lost weight. All patients underwent transthoracic echocardiogram at baseline and at follow-up. RESULTS: At baseline, three groups were comparable in all clinical and metabolic parameters except Group 3 had highest body mass index. The three groups had similar echocardiographic parameters except Group 3 had the worst LV systolic function [global longitudinal strain (GLS)]. At follow-up, LV ejection fraction and diastolic function improved with a reduction in filling pressures in Group 2 and more so in Group 3. LV filling pressures in Group 1 increased. There was a significant improvement in GLS in Group 2 and more so in Group 3. Despite GLS being the worst in Group 3 at baseline, this was comparable between Groups 2 and 3 at follow-up. CONCLUSIONS: In overweight patients with type 2 diabetes, weight loss and improved glycaemic control had additive beneficial effects on improving LV systolic and diastolic function.

Left ventricular diastolic reserve in patients with type 2 diabetes mellitus.

AIMS: Diastolic reserve is the ability of left ventricular filling pressures to remain normal with exercise. Impaired diastolic reserve may be an early sign of diabetic cardiomyopathy. We aimed to determine whether diastolic reserve differs in type 2 diabetes (DM) compared with non-DM, and to identify clinical, anthropological, metabolic and resting echocardiographic correlates of impaired diastolic reserve in patients with DM. METHODS AND RESULTS: 237 patients (aged 53±11 years, 133 DM, ejection fraction 68±9%) underwent rest and exercise echocardiography. Mitral E and septal e' were measured at rest, immediately post, and 10 min into recovery. Analysis of covariance (ANCOVA) and binary regression with continuous outcomes were used to model e' and E/e' changes with exercise to identify impaired diastolic reserve defined as post-exercise E/e' ≥15. After adjusting for baseline differences, patients with DM immediately post-exercise had a lower septal e', a lower Δe' (1.2 vs 2.3 cm/s, p=0.006) and a higher Δ septal E/e' (1.7 vs 0.08, p<0.001) than patients without DM. In patients with normal resting E/e' of ≤8 (n=130), DM had a significantly higher post-exercise septal E/e' and a higher Δseptal E/e' (2.63 vs 0.50, p<0.001). E/e' in patients with DM remained significantly elevated up to 10 min post-exercise. Hypertension, longer duration of insulin therapy, poorer glycaemic control, worse renal function, larger left atrial volume and lower septal e' were independent correlates of impaired diastolic reserve in patients with DM. CONCLUSIONS: Patients with DM have impaired diastolic reserve manifest as a blunted e' response with exercise, persisting into recovery. Clinical, anthropometric, metabolic and echocardiographic correlates of impaired diastolic reserve in patients with DM were identified. An impaired LV diastolic reserve may be the underlying pathophysiological mechanism in patients with DM with unexplained exertional dyspnoea and may allow earlier detection of DM cardiomyopathy.

Endothelial function and left ventricular diastolic functional reserve in type 2 diabetes mellitus.

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' (ß=0.002, p<0.001, R(2)=0.47) and diastolic reserve index (ß=0.030, p<0.001, R(2)=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 (R(2)=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.