Vectocardiographic "bites" as possible early findings of cardiac involvement in diabetic patients without clinical evidence of heart disease.

We performed a standard vectorcardiogram (VCG) in 87 diabetics, aged 20-77 years, orally- or insulin-treated, and in 41 normal subjects. None had cardiac history or symptoms. Among diabetics, 31 had no vectocardiographic abnormalities, 23 had various VCG changes, 33 showed electrical "bites" of various length (6-22 msec) and voltage (0.05-0.3 mV). In 8 normal subjects (19.4%) we found "bites" of similar voltage and length as in diabetic patients. A significantly positive linear relation was found between "bites" length and diabetes duration, in insulin-dependent diabetics only. By step-wise regression analysis we detected, in all diabetic patients with "bites," at a fixed value of diabetes duration, a significantly negative relation between "bites" length and patients' age. Moreover, the insulin treated patients showed a metabolic regulation index significantly worse than orally-treated diabetics; also diabetes duration was significantly higher in insulin-treated subjects. If "bites" may reflect an early heart involvement in diabetes, insulin-dependent patients seem to have a more severe cardiac damage in dependence of the diabetes duration. Finally, in the younger diabetics the heart diseases seems to be earlier and more advanced.