IMPROVED VISUAL-EVOKED POTENTIAL LATENCIES IN POORLY CONTROLLED DIABETIC-PATIENTS AFTER SHORT-TERM STRICT METABOLIC CONTROL

OBJECTIVE- To determine whether short-term strict control of blood glu cose can improve abnormal visual evoked potentials (VEPs) in poorly co ntrolled diabetic patients with no overt diabetic complications. RESEA RCH DESIGN AND METHODS- VEPs (P100 wave latencies) were recorded in 12 poorly controlled diabetic patients (7 with insulin-dependent diabete s mellitus and 5 with non-insulin-dependent diabetes mellitus) before and after at least 3 days of near normoglycemia obtained by continuous subcutaneous insulin infusion (CSII). Exclusion criteria were overt d iabetic neuropathy or retinopathy. The control subjects were 12 health y subjects matched for age and sex. Fifty-two other subjects formed a reference control population. The intra-individual coefficient of vari ation for P100 latency was <3%. RESULTS- The P100 latencies were longe r in diabetic patients than in control subjects (means of both eyes +/ - SD: 116.8 +/- 10.1 vs. 106.2 +/- 4.5 ms, P < 0.01), and 4 of the 12 diabetic patients had abnormal VEPs. After 3 days of close blood gluco se control (mean blood glucose profile fell from 13.7 +/- 2.2 mmol/l t o 6.8 +/- 1.2 mmol/l, P < 0.01), the mean P100 latencies were signific antly shorter (112.5 +/- 7.6 ms, P < 0.01) but were still significantl y longer than control values. The longer the initial P100 latency, the greater the decrease after CSII. There was no correlation between the fall in blood glucose and improvement in VEPs. CONCLUSIONS- Short-ter m blood glucose normalization is associated with improved P100 wave la tency in uncomplicated diabetic patients. These data suggest that abno rmal VEPs are partly reversible and include functional disturbances re lated to glucose metabolism.