However, another study published around the same time identified a very minor subpopulation (2–5%) of islet cells in a small cohort of established T1D donors that were double-positive for glucagon and insulin, but lacked canonical alpha cell identity markers Aristaless related homeobox (ARX) and DNA methyltransferase 1 (DNMT1) [117]. This evidence concerns the gene GCG and type 1 diabetes mellitus.