Influence of Caffeine on Heart Rate Variability in Patients With Long-Standing Type 1 Diabetes

Influence of Caffeine on Heart Rate Variability in Patients With Long-Standing Type 1 Diabetes Tristan Richardson , MRCP 1 , Adrian Rozkovec , FRCP 2 , Peter Thomas , PHD 3 , Jacqueline Ryder 1 , Candy Meckes , BSC 2 and David Kerr , FRCP 1 1 Bournemouth Diabetes & Endocrine Centre, Bournemouth, U.K 2 Department of Cardiology, Royal Bournemouth Hospital, Bournemouth, U.K 3 Dorset Research and Development Unit & Bournemouth University, Bournemouth, U.K Address correspondence and reprint requests to Dr. Tristan Richardson, Bournemouth Diabetes & Endocrine Centre, Royal Bournemouth Hospital, Castle Lane East, Bournemouth, BH7 7DW, U.K. E-mail: tristan.richardson{at}rbch-tr.swest.nhs.uk Abstract OBJECTIVE —The effect of caffeine on cardiovascular health remains controversial. Patients with long-standing type 1 diabetes are at risk of autonomic failure and sudden cardiac death. We investigated the effects of caffeine on autonomic dysfunction (as assessed by heart rate variability [HRV]) in this high-risk group and in a control population. RESEARCH DESIGN AND METHODS —Using a randomized blinded, placebo-controlled, crossover design trial, we examined 2 weeks of caffeine consumption (250 mg twice daily) on HRV in 20 type 1 diabetic patients and 10 matched healthy volunteers. RESULTS —Baseline HRV was blunted in the diabetic patients ( P < 0.0005 vs. control subjects) and markedly increased by caffeine in both groups (+103% in the group with diabetes [ P = 0.009] and +38% in control subjects [ P = 0.002]). The caffeine-associated increase in HRV was not statistically different between the control and the type 1 diabetes groups ( P = 0.16). CONCLUSIONS —Modest amounts of caffeine improved autonomic function in diabetic patients and healthy volunteers. For individuals with abnormal HRV, regular caffeine use may have the potential to reduce the risk of cardiovascular events. CGMS, continuous glucose monitoring system ECG, electrocardiogram HF, high frequency HRV, heart rate variability LF, low frequency sNN50, sum of mean RR intervals >50 ms/h Footnotes Accepted February 10, 2004. Received November 20, 2003. DIABETES CARE