QT interval prolongation in type 2 (non-insulin-dependent) diabetic patients with cardiac autonomic neuropathy.

QT interval alterations were measured in 41 non-insulin-dependent (type 2) diabetic patients and 14 age- and sex-matched control subjects. Cardiac autonomic neuropathy (CAN) was assessed by noninvasive tests (deep breathing, Valsalva maneuver and lying-to-standing) and diabetics were divided into three groups according to the results of these tests: diabetics with definitive (n = 14), early (n = 13) and without (n = 14) CAN. The corrected values of QT intervals (QTc) at rest were significantly longer in diabetics with definitive (447 +/- 5 ms; p less than 0.001), early (426 +/- 5 ms; p less than 0.05) and without (424 +/- 5 ms; p less than 0.05) CAN than in controls (407 +/- 5 ms). Moreover, QTc intervals at rest were significantly (p less than 0.01) longer in diabetics with definitive CAN than in diabetics with early and without CAN. QTc intervals at maximum tachycardia, induced by Valsalva maneuver, were considerably longer in diabetics with definitive CAN (451 +/- 6 ms) than in controls (407 +/- 6 ms; p less than 0.001) and in diabetics with early (434 +/- 6 ms; p less than 0.05) or without (422 +/- 6 ms; p less than 0.01) CAN. Furthermore, QTc intervals at maximum tachycardia were significantly (p less than 0.01) longer in diabetics with early CAN than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)