Mandatory oral glucose tolerance tests identify more diabetics in stable patients with chronic heart failure: a prospective observational study

Postprandial increase in glucagon-like peptide-1 is blunted in severe heart failure

The relationship between disturbances in glucose homeostasis and heart failure (HF) progression is bidirectional. However, the mechanisms by which HF intrinsically impairs glucose homeostasis remain unknown. The present study tested the hypothesis that the bioavailability of intact glucagon-like peptide-1 (GLP-1) is affected in HF, possibly contributing to disturbed glucose homeostasis. Serum concentrations of total and intact GLP-1 and insulin were measured after an overnight fast and 15 min after the ingestion of a mixed breakfast meal in 49 non-diabetic patients with severe HF and 40 healthy control subjects. Similarly, fasting and postprandial serum concentrations of these hormones were determined in sham-operated rats, and rats with HF treated with an inhibitor of the GLP-1-degrading enzyme dipeptidyl peptidase-4 (DPP4), vildagliptin, or vehicle for 4 weeks. We found that HF patients displayed a much lower increase in postprandial intact and total GLP-1 levels than controls. The increase in postprandial intact GLP-1 in HF patients correlated negatively with serum brain natriuretic peptide levels and DPP4 activity and positively with the glomerular filtration rate. Likewise, the postprandial increases in both intact and total GLP-1 were blunted in HF rats and were restored by DPP4 inhibition. Additionally, vehicle-treated HF rats displayed glucose intolerance and hyperinsulinemia, whereas normal glucose homeostasis was observed in vildagliptin-treated HF rats. We conclude that the postprandial increase in GLP-1 is blunted in non-diabetic HF. Impaired GLP-1 bioavailability after meal intake correlates with poor prognostic factors and may contribute to the establishment of a vicious cycle between glucose disturbance and HF development and progression.

Long-term mortality is increased in patients with undetected prediabetes and type-2 diabetes hospitalized for worsening heart failure and reduced ejection fraction

Background

We assessed the prevalence of newly diagnosed prediabetes and type-2 diabetes mellitus (T2DM), and their impact on long-term mortality in patients hospitalized for worsening heart failure with reduced ejection fraction (HFrEF).

Methods

We included patients hospitalized with HFrEF and New York Heart Association (NYHA) functional class II–III. Baseline two-hour oral glucose tolerance test was used to classify patients as normoglycaemic or having newly diagnosed prediabetes or T2DM. Outcomes included post-discharge all-cause and cardiovascular mortality during the median follow-up of 2.1 years.

Results

At baseline, out of 150 patients (mean-age 57 ± 12 years; 88% male), prediabetes was diagnosed in 65 (43%) patients, and T2DM in 29 (19%) patients. These patients were older and more often with NYHA class III symptoms, but distribution of comorbidities was similar to normoglycaemic patients. Taking normoglycaemic patients as a reference, adjusted risk of all-cause mortality was significantly increased both in patients with prediabetes (hazard ratio, 2.6; 95% confidence interval (CI), 1.1–6.3; p = 0.040) and in patients with T2DM (hazard ratio, 5.3; 95% CI, 1.7–15.3; p = 0.023). Likewise, both prediabetes (hazard ratio, 2.9; 95% CI, 1.1–7.9; p = 0.041) and T2DM (hazard ratio, 9.7; 95% CI 2.9–36.7; p = 0.018) independently increased the risk of cardiovascular mortality compared with normoglycaemic individuals. There was no interaction between either prediabetes or T2DM and heart failure aetiology or gender on study outcomes (all interaction p-values > 0.05).

Conclusions

Newly diagnosed prediabetes and T2DM are highly prevalent in patients hospitalized for worsening HFrEF and NYHA functional class II–III. Importantly, they impose independently increased long-term risk of higher all-cause and cardiovascular mortality.

Exercise training improves insulin release during glucose tolerance testing in stable chronic heart failure patients

PURPOSE

Chronic heart failure (CHF) patients often present with (pre)diabetes, which negatively influences prognosis. Unlike the proven effect of exercise on glucose regulation in the general population, its effect in CHF is unclear. Therefore, this study aimed at investigating the effect of exercise training on glucose regulation in stable CHF patients.

METHODS

Twenty-two CHF patients were randomized into training (EX, n = 15) and control (CON, n = 7) groups. Before and after a 12-week training intervention involving endurance and resistance training, glucose tolerance (2-hour oral glucose tolerance test), exercise tolerance (cardiopulmonary exercise test), muscle strength (isokinetic dynamometer), heart function (echocardiography), glycated hemoglobin, body composition (dual-energy x-ray absorptiometry), and quality of life (EQ5D) were assessed.

RESULTS

At baseline, glucose levels 2 hours after glucose intake were elevated in both groups. Whereas area under the glucose curve did not change, area under the insulin curve decreased following training (EX, -13 ± 23% vs CON, +22 ± 33%; P < .05). Changes in the ratio of mitral peak velocity of early filling/early diastolic mitral annular velocity and waist-to-hip fat mass ratio were related to changes in the insulin curve. Exercise training resulted in improved oxygen uptake at the second ventilatory threshold (EX, +10 ± 5% vs CON, -8 ± 5%; P < .05) and isokinetic strength endurance of the upper leg (EX, +25 ± 9% vs CON, -6 ± 5%; P < 0.05). Lean body tissue was increased by 2.2 ± 0.5% in EX versus 0.2 ± 0.6% in CON (P < .05).

CONCLUSION

Our data suggest that exercise training attenuates worsening of glucose regulation typically seen in a stable CHF population.