Lastly, GLP-1 did not correlate with body mass index (BMI) for PD subjects (n = 18, p = 0.72, r = 0.09, r2 = 0.01) nor for PD and control subjects when combined (n = 26, p = 0.34, r = 0.20, r2 = 0.04) (data not shown). Here, GCG is linked to Parkinson disease.