In the absence of SST, 20 or 30 mmol/L glucose stimulates glucagon release. In the absence of SST, 20 or 30 mmol/L glucose stimulates glucagon release. A, C, and E: Islets from Sst+/+ or Sst−/− mice were perifused with MixAA 6 (A) or MixAA 2 (C and E). The glucose concentration was changed between 1 (G1), 7 (G7), 20 (G20), and 30 (G30) mmol/L as indicated. For one series of experiments shown in C, 23 mmol/L of sucrose (Suc 23) was added to a medium containing G7 when indicated. At the end of the perifusion, diazoxide (Dz; 250 µmol/L for Sst+/+ islets) or SST14 (100 nmol/L for Sst−/− islets) was added to have a basal secretion. Traces are means ± SE for three to four experiments with islets from different preparations. B, D, and F: Univariate scatter plots showing individual data and means ± SE of the average glucagon secretion calculated from the experiments shown on the left (G7, mean of 20–40 min and 120–140 min; G20, G30, or G7 + Suc 23, mean of 48–100 min). *P < 0.05 and **P < 0.01 for comparison between different conditions or islets of different mouse models. The y-axis labels for A–F are at the top of each column of panels. Bao-Khanh Lai et al. Diabetes 2018;67:2239-2253 ©2018 by American Diabetes Association