Follow-up Study on Peripheral Neuropathy in Insulin-dependent Diabetes Mellitus in Childhood

Lee, Eun Sil; Lee, Young Hwan; Moon, Han Ku; Park, Yong Hoon; Hah, Jung Sang

Abstract

PURPOSE: Peripheral neuropathy is the most common chronic complication of insulin- dependent diabetes mellitus, which is one of the most frequent endocrine metabolic disorders in children. However, there are very few long-term follow-up studies on the condition in publication and none in Korean literature. In order to find out the correlation between the severity of peripheral neuropathy and glycosylated hemoglobin level, an indicator of diabetes control, a follow-up study was conducted on cases of insulin- dependent diabetes mellitus.
METHODS
The study was conducted on 37 patients with insulin-dependent diabetes mellitus (12 males, 25 females, aged 7-21 years) who were diagnosed and were being treated in general hospitals in the Taegu-Kyungpook area from 1994 to 1998. They were also subject to nerve conduction velocity test at least two times with an interval of one or more years. Nerve conduction velocity was measured by using type MEM-3102 apparatus of Nihon Kohden (on motor and sensory component of left ulnar nerve and median nerve, motor component of left and right peroneal, posterior tibial nerve, sensory component of left and right sural nerve) and medical history was taken, neurological examination was done and glycosylated hemoglobin levels were measured with each test.
RESULTS
The total number of nerve conduction velocity tests was 89 and the results were divided into 5 groups [normal : 14 cases (15.7%); borderline: 35 cases (39.3%); mononeuropathy : 2 cases (2.2%); mild polyneuropathy : 22 cases (24.7%); severe polyneuropathy : 16 cases (18.0%)] by the number and distributions of nerves that were found abnormal. Ten of the 26 cases, belonging to the normal or borderline group in the first test, showed signs of peripheral neuropathy in later tests, and of the 11 cases with peripheral neuropathy in the first test, none improved to be included in the normal or borderline group in the follow-up study. The mean glycosylated hemoglobin level was 9.2+/-2.5% in normal group, 11.9+/-3.2% in borderline group, 13.0+/-0.3% in mononeuropathy group, 12.0+/-3.7% in mild polyneuropathy group and 14.8+/-4.0% in severe polyneuropathy group, and glycosylated hemoglobin level rose with the severity of the neuropathy (r=0.372, p< 0.01). In the 9 cases that had shown improvement of peripheral neuropathy, glycosylated hemoglobin levels decreased significantly by an average of 3.5+/-1.3% with each level of improvement (t-test, p<0.05), but in 20 cases with deteriorating nerve conduction velocity, there was no significant correlation with increase in glycosylated hemoglobin levels.
CONCLUSION
Peripheral neuropathy complicating insulin-dependent diabetes mellitus can occur during diabetes treatment and does not improve easily once it occurs. In this study, the glycosylated hemoglobin level was shown to have a high degree of correlation with the occurrence and progression of neuropathy, which means that control of hyperglycemia is difficult and also that stricter control of blood glucose during early stages of diabetes is necessary to prevent neuropathy. Follow-up studies with bigger samples and longer time will be needed for a more detailed look.