Figure 4.

(A) β cell response to an increase in glucose during a hyperglycemic clamp, and (B) α cell response to insulin-induced hypoglycemia during a hypoglycemic clamp in individuals with T1D by peak C-peptide during a mixed-meal tolerance test (negative, <0.02 ng/mL; low, 0.05–0.60 ng/mL; intermediate, >0.60–1.20 ng/mL; and high, >1.20 ng/mL). An increase in C-peptide in response to hyperglycemia and an increase in glucagon in response to hypoglycemia were observed only in the group with the highest residual C-peptide production that may represent a minimal functional islet reserve. Data are from Ref. 89.