Diabetes was still an untreatable fatal disease in 1922

Evidence

For Weil, Gerlach would have been the ideal candidate: he was young, with a solid university career behind him, an `upper-class communist’; but Gerlach died in October 1922 at the age of thirty-six from diabetes, a disease against which medicine then was still powerless. — Rolf Wiggershaus, The Frankfurt School, 73