Newer studies however, do not support the contention of a generalized defect in nutrient-related GLP-1 secretory responses in people with T2D, but rather suggest that the inter-individual differences in GLP-1 secretion, age of patients, duration of diabetes, concomitant drug therapy, and other variables play a role, and preclude definitive conclusions that diabetes is invariably associated with reduced GLP-1 secretion [22]. This evidence concerns the gene GCG and type 2 diabetes mellitus.