INTRODUCTION: Diabetes mellitus is frequently accompanied by cardiac rhythm 
disorders. On the other hand, atrial fibrillation is the most frequent cardiac 
arrhythmia in adult population [1, 2]. According to some of the large 
epidemiological studies diabetes mellitus is among independent risk factors for 
development and persistence of atrial fibrillation [3]. Both diabetes mellitus 
and atrial fibrillation independently increase the risk of thromboembolism, 
especially of stroke [3-5]. It is obvious that rhythm control, i.e. restoration 
and maintenance of sinus rhythm, may be essential for prevention of 
thromboembolism in these patients.
THE AIM OF THE STUDY: The aim of this study is to analyse the impact of diabetes 
mellitus on rhythm control in patients with persistent atrial fibrillation.
METHODS: We analysed the impact of diabetes mellitus and other clinical and 
echocardiographic parameters (age, gender, current arrhythmia duration, presence 
of previous episodes of persistent atrial fibrillation, cardiac and/or 
noncardiac diseases, left atrial diameter and left ventricular ejection 
fraction) on outcome of attempted cardioversion in patients with persistent 
atrial fibrillation admitted to Cardiologic Department of the Institute of 
Cardiovascular Diseases, Clinical Centre of Serbia, between January 1992 and 
December 1999. We also analysed retrospectively the impact of diabetes mellitus 
and other parameters listed above on the presence of previous episodes of atrial 
fibrillation in our patients, that at our opinion reflected the possibilities of 
sinus rhythm maintenance in these patients. All continuous parameters were 
expressed as mean value and standard deviation. Statistical significance of 
differences between variables was examined using Chi-square test. For 
identification of independent predictors of examined outcomes we used multiple 
logistic regression model with 95% of confidence interval. Statistical analysis 
was performed using Statistical Package for Social Sciences (SPSS) programme.
RESULTS: Of 378 patients with currently persistent atrial fibrillation, aged 
mean 53.98 +/- 11.69 years, there were 266 (70.4%) men. Diabetes mellitus was 
previously diagnosed in 27 (7.1%) patients, cardiac diseases in 223 (59.0%), 
noncardiac diseases in 47 (12.4%) and 140 (37.0%) patients had "lone" atrial 
fibrillation. Left atrial enlargement was noted in 224 (59.3%) patients, and 
reduced left ventricular ejection fraction in 82 (21.7%). Atrial fibrillation 
lasted 48 hours to 9 years, mean 8.5 +/- 18.14 months before cardioversion. 
While 43 patients had previous episodes of persistent AF for last 1-30 years, 
mean 10.5 +/- 7.3,335 patients never experienced AF before. There was a 
statistically significant difference in percent of diabetic patients (18.6%/43 
vs. 5.7%/335, value of Chi-square test = 7.759, p < 0.01) in these two groups. 
We analysed the impact of diabetes mellitus on outcome of attempted 
cardioversion and on presence of previous episodes of AF reflecting the success 
in maintaining sinus rhythm. Multiple logistic regression models for all of 378 
patients, with dependent variable being present in previous recurrent atrial 
fibrillations and independent variables of clinical and echocardiographic 
parameters as listed, identified diabetes mellitus to be an independent 
predictor of repeated atrial fibrillations with relative risk of 4.6 (CI 95%). 
When dependent variable in the same model was outcome of cardioversion (sinus 
rhythm is restored in 281/378 patients--74%) diabetes mellitus was not among 
independent predictors of successful cardioversion.
DISCUSSION: The relationship between atrial fibrillation and diabetes mellitus 
is not completely understood, including the impact of known complications of 
diabetes mellitus on electrophysiological properties of atrial myocardium and 
development of atrial fibrillation [6]. Besides being the independent risk 
factor for occurrence of atrial fibrillation, diabetes mellitus, according to 
our results, appears to influence the possibilities of maintaining sinus rhythm 
after cardioversion of permanent atrial fibrillation in diabetic patients. We 
found that patients with diabetes mellitus and persistent atrial fibrillation 
may be successfully converted to sinus rhythm like any other group of patients, 
but the presence of diabetes mellitus increases the risk of arrhythmia 
recurrence for 4.6 times compared to patients without diabetes mellitus. 
Obviously, diabetic patients need to be treated with more efficacious 
antiarrhythmics from the very beginning, including amiodarone, which 
successfully prevents recurrent atrial fibrillation in the majority of patients 
[7, 8].
CONCLUSION: We concluded that diabetes mellitus independently predicts the 
presence of recurrent atrial fibrillation but does not influence the possibility 
of sinus rhythm restoration. The relationship between atrial fibrillation and 
diabetes mellitus needs further investigation.