GCG and type 1 diabetes mellitus: The mean islet glucagon-positive area was increased in donors with type 1 diabetes (22.94 ± 1.61% vs 41.61 ± 3.41% vs 39.79 ± 2.81% for non-diabetic donors vs donors with short-duration type 1 diabetes vs long-duration type 1 diabetes, respectively) (Fig. 5b), yet glucagon expression in islets was highly heterogenous, and the median islet fluorescence intensity of glucagon was comparable among donor groups (Fig. 5c).