Measurement of serum CP concentrations during a standardized mixed meal tolerance test (MMTT) is a well-established, practical method of assessing nutrient stimulated beta cell secretory function [6], with peak CP concentrations > 0.2 nmol/L being associated with improved glycemic control, less hypoglycemia and fewer microvascular complications in individuals living with T1D [7,8]. The gene discussed is CP; the disease is type 1 diabetes mellitus.