Submitted to: American Heart Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/27/2004
Publication Date: 1/15/2005
Citation: Vrtovec, M., Vrtovec, B., Briski, A., Kocijancic, A., Anderson, R.A., and Radovanevic, B. 2005. Chromium supplementation shortens QTc interval duration in patients with type 2 diabetes. American Heart Journal. 149(4): 632-639. Interpretive Summary: The incidence of type 2 diabetes, one of the leading causes of morbidity and mortality, is increasing at an alarming rate. Experimental and clinical studies demonstrate that chromium supplementation often improves the signs and symptoms of diabetes including elevated blood sugar, fats and insulin. Because these factors have potential roles in the development of atherosclerosis, chromium deficiency may represent a risk factor for cardiovascular diseases. We measured changes in heart function, similar to those that are measured during a routine electrocardiogram, to determine if the heart function of people with diabetes improves when chromium nutrition improves. We demonstrated that QTc interval prolongation, which has been shown to be a powerful predictor of total mortality, cardiac death, and future stroke in patients with type 2 diabetes mellitus, improved when chromium nutrition improved. This work will be of importance to the medical community involved in diabetes and cardiovascular diseases but also the lay public for improved health.
Technical Abstract: We investigated the potential effects of chromium supplementation on QTc interval duration in patients with type 2 diabetes. Sixty patients with type 2 diabetes mellitus were randomly assigned to two groups. Group A received 1000 'g of chromium as chromium picolinate (CrPic) daily for 3 months, followed by placebo for 3 months; group B was treated with placebo for the first 3 months and CrPic in the next 3 months. At each visit, QT interval was measured on a standard electrocardiogram by averaging 3 consecutive beats in leads II and V4 and corrected for heart rate with Bazett formula. Although baseline QTc interval was similar in both groups (422 ± 34 milliseconds in group A vs 425 ± 24 milliseconds in group B, P = .77), QTc interval at 3 months was shorter in group A (406 ± 35 milliseconds) than in group B (431 ± 26 milliseconds, P = .01). In the following 3 months, QTc interval shortened in group B but not in group A, which resulted in a comparable QTc interval duration of both groups at the end of the study (414 ± 28 milliseconds in group A vs 409 ± 22 milliseconds in group B, P = .50). Apart from body mass index (31.4 ± 4.2 kg/m2 in patients with QTc shortening vs 28.7 ± 4.2 kg/m2 in patients without QTc shortening, P = .03), none of the clinical and laboratory variables predicted QTc interval shortening in our patient cohort. In conclusion, short-term chromium supplementation shortens QTc interval in patients with type 2 diabetes mellitus.