A long-term diabetic autonomic nervous abnormality. Reduced variations in resting heart rate measured by a simple and sensitive method.

Three types of variation in resting pulse rate were measured, using simple and reproducible methods, in 44 young juvenile diabetics and 11 controls. Diabetics with few years duration of the disease showed normal values of both long-term and cyclic fluctuations, as well as of non-systematic, random variation from beat-to-beat. All three types of variation were reduced in long-term diabetics, and the reduction was in all cases correlated with the duration of diabetes. The decrease in non-systematic, beat-to-beat variation attained statistical significance after 5 to 10 years duration of diabetes. It is concluded that reduced variation in resting pulse rate is a long-term diabetic manifestation and that the decrease of non-systematic, beat-to-beat variations in diabetics is a useful indicator of functional abnormalities of the autonomic nervous system.