Introduction: Optic nerve sheath diameter (ONSD) measurement accurately detects elevated intracranial pressure and may facilitate early recognition of diabetic ketoacidosis-related cerebral edema (DKA-CE). Our objective was to assess how ONSD measurement varies during T1D-related illness, in order to determine the potential of this tool for discrimination of subclinical DKA-CE.

Methods: We prospectively enrolled patients aged 7–18 years into three study arms: 1) well-controlled type 1 diabetes; 2) type 1 diabetes with hyperglycemia; 3) DKA. Exclusion criteria included >10 mL/kg of intravenous fluid or insulin prior to transfer, or conditions predisposing to increased intracranial or intraocular pressure. ONSD measurements were obtained within 4h of arrival. One-way ANOVA and multivariable linear regression were used to assess ONSD between groups and association with known DKA-CE risk factors, respectively. Reliability measures were assessed and target enrollment was 36 patients per arm based on sample size calculations.

Results: We enrolled 108 patients. No patients had clinically overt DKA-CE. The between group difference in mean ONSD (mm ± SD) among patients with well-controlled type 1 diabetes (5.2 ± 0.85), T1D with hyperglycemia (5.0 ± 0.91), and DKA (5.2 ± 0.92) was not significant (p=0.79). Mean ONSD was not independently associated with presenting laboratory parameters, known DKA-CE risk factors, or time to ultrasound. There was good agreement between sonographers (88.9% agreement; intraclass correlation coefficient 0.71).

Conclusion: ONSD measurements did not vary significantly based on T1D-related illness severity, and thus, may not sufficiently discriminate subclinical DKA-CE.