Left ventricular diastolic dysfunction (DD) may lead to heart failure and is found in approximately 50% of asymptomatic patients with type 2 diabetes mellitus (T2DM). Little is known about the effect of exercise on DD in T2DM (1), but moderate-intensity exercise (MIE) seems insufficient to improve myocardial function. Studies indicate that high-intensity interval exercise (HIIE) is more effective than MIE in reducing cardiovascular risk factors in T2DM and in reversing left ventricular remodeling in patients with postinfarction heart failure. The aim of this study was to compare the effect of HIIE (4 Â 4–min interval, 90% to 95% maximal heart rate, 40 min/bout, 3/week) and MIE according to current guidelines ($10 min/bout, 210 min/week) on DD, defined as peak early diastolic tissue Doppler velocity (e0)< 8 cm/s (2), and other cardiovascular risk factors in patients with T2DM and DD. Our hypothesis was that HIIE, more than MIE, would improve these measures. We prescreened 83 patients for DD who had T2DM for< 10 years and no known cardiovascular disease. A total of 47 patients (55.9 Æ 6.0 years; 36% female; duration of T2DM: 3.6 Æ 2.5 years) met the inclusion criteria (e0< 8 cm/s). The subjects were randomized to home-based MIE (n ¼ 23) and supervised HIIE (n ¼ 24) and tested at baseline, 12 weeks (MIE, n ¼ 17; HIIE, n ¼ 20), and 1 year (MIE, n ¼ 16; HIIE, n ¼ 16). The patients in the MIE group were younger than those in the HIIE group (mean 54.7 Æ 5.3 vs. 58.6 Æ 5.0 years) but did not differ by sex (35.3% vs. 40.0% female) or duration of T2DM (3.0 Æ 2.6 vs. 4.2 Æ 2.3 years). After 12 weeks, exercise was home based in both groups. Repeated-measures analysis of variance models (generalized linear model, linear mixed model) were applied to compare intervention groups with respect to mean change in outcome variables. Results from baseline to 12 weeks are shown in Table 1. Both groups showed improved diastolic function (e0) at rest, but HIIE showed more improvement than MIE. Only HIIE improved transmitral peak early diastolic velocity (E), diastolic filling pressure (E/e0), and E/A ratio. A higher proportion of patients in the HIIE group had improved diastolic function to e0> 8 cm/s during the 12-week period (80.0% vs. 41.2%; p ¼ 0.02, chi-square test). During exercise, only HIIE improved diastolic function (E). Lack of improvement in e0 during exercise may be explained by the use of different echocardiographic methods at rest and during exercise.

A nonsignificant decrease in e0 at rest was seen from 12 weeks to 1 year (À0. 45 and À0. 24 cm/s for HIIE and MIE, respectively). However, in contrast to the MIE group, the HIIE group still had improved diastolic function (e0) compared with baseline. Improvement in E was sustained in the HIIE group after 1 year.