Objective: Many stroke patients make a partial recovery in function during the first 3 months, partially through promoting insulin-like growth factor-1 (IGF-1) function. A prognostic biomarker that associates with IGF-1 function may predict clinical outcome and recovery of stroke. This study evaluated plasma concentrations of IGF-1, IGF binding protein (IGFBP)-3 and cyclic-glycine-proline (cGP) and their associations with clinical outcome in stroke patients. Methods: Thirty-four patients were recruited within 3 days of stroke. Clinical assessments included the National Institutes of Health Stroke Scale (NIHSS) within 3 days (baseline), and at days 7 and 90; the modified Rankin Scale (mRS) and FuglMeyer Upper-Limb Assessment Scale (FM-UL) at days 7 and 90. Plasma samples were collected from the patients at the baseline, days 7 and 90. Fifty age-matched control participants with no history of stroke were also recruited and provided plasma samples. IGF-1, IGFBP-3, and cGP concentrations were analyzed using ELISA or HPLC-MS. Results: Baseline concentrations of IGFBP-3, cGP, and cGP/IGF-1 ratio were lower in stroke patients than the control group. The neurological scores of stroke patients were improved and plasma cGP and cGP/IGF-1 ratio increased over time. Baseline cGP/IGF-1 ratio was correlated with the NIHSS scores at day 90 and the changes in NIHSS scores from the baseline to 90 days. Interpretation: Low cGP concentrations and cGP/IGF-1 ratio in stroke patients suggest an impaired IGF-1 function. The cGP/IGF-1 ratio at admission maybe further developed as a prognostic biomarker for stroke recovery.