It is not clear whether blood glucose (BG) affects the risk of peripherally inserted central catheter (PICC)-related upper extremity venous thrombosis (PRUEVT). A case-control study was conducted comparing patients with PRUEVT versus patients with PICCs who did not develop PRUEVT. BG on admission was significantly higher among cases with PRUEVT than controls. No significant differences were found between the groups in hemoglobin A1c or BG on the third day of hospitalization. PRUEVT cases were more likely to be diabetic, but this did not reach statistical significance. The time that a PICC was in place before PRUEVT was diagnosed was longer for diabetic patients, but the authors believe this result must be viewed with caution.