Does Diabetes Alter CSF Total Protein Levels? A Retrospective Cohort Study

Background and Purpose: Elevation of total protein level in cerebrospinal fluid (CSF-TP) in diabetic patients is often disregarded by clinicians. However, existing studies on the topic have significant limitations, and therefore we aimed to explore the relationship between diabetes and CSF-TP in a large database of CSF samples. Methods: Retrospective review of all diagnostic lumbar punctures at the Ottawa Hospital between 1996-2016. Patients were excluded if they had elevated CSF cell counts, or a condition known to elevate CSF-TP. Multivariate linear regression modeling considered the effects of age, sex, and diabetes. Results: Among 6124 patients (746 with diabetes, 5378 without), mean CSF-TP did not differ significantly between groups (0.39 and 0.35 mmol/L, p = 0.2). When controlled for age and sex, there was no significant effect of diabetes on CSF-TP and no significant correlation between mean serum glucose and CSF-TP (R-2 = 0.12). Conclusions: CSF-TP did not differ significantly between diabetic and non-diabetic groups, once the influence of age and sex was controlled. Elevated CSF-TP should be regarded as pathologic, even in the setting of diabetes.