Hypoglycemic effect of cibenzoline in patients with abnormal glucose tolerance and frequent ventricular arrhythmias

While some antiarrhythmic agents have potential hypoglycemic effects and in deed some reports of hypoglycemic adverse effect of those drugs, no systema tic reports have been issued. We studied the hypoglycemic effects of cibenz oline, a class I antiarrhythmic agent. Cibenzoline succinate (150-300 mg/da y) was given orally for 12 weeks to 10 patients who had ventricular prematu re complexes (VPCs) of >1000 per 24 hours and abnormal glucose tolerance be fore treatment with cibenzoline. Abnormal glucose tolerance, judged by a 75 -g oral glucose tolerance test (OGTT), was defined as the response designat ed as "diabetic" or "borderline" type according to the criteria specified b y the Japan Diabetes Society. In OGTT, the insulinogenic index (defined as the ratio of the increment of IRI [immunoreactive insulin] to that of plasm a glucose at 30 minutes after a glucose load) and the sum of IRI (Sigma IRI ) were also determined. Holter ECG recordings, OGTT, and measurements of fa sting plasma glucose IRI, and HbA(1c) were performed before and during cibe nzoline treatment. Cibenzoline caused VPC reduction of > 70% in 6 of the 10 patients. The drug significantly decreased fasting plasma glucose and HbA( 1c) (mean +/- SD) 12 weeks after treatment, from 6.18 +/- 0.92 mM/L to 5.54 +/- 1.08 mM/L and from 6.17 +/- 1.03% to 5.83 +/- 0.96%, respectively (P < 0.05). While it significantly increased fasting IRI from 4.99 +/- 1.50 to 6.51 +/- 1.47 <mu>U/mL (P < 0.01), the insulinogenic index from 0.33 +/- 0. 26 to 0.65 +/- 0.38 (P < 0.05), and Sigma IRI from 168 +/- 67 muU/mL to 199 +/- 46 (P < 0.05). Cibenzoline exerted a hypoglycemic effect, facilitating insulin secretion in patients with abnormal glucose tolerance and ventricu lar arrhythmias.