This technology has been available for decades – but it’s not available. I was told sometime in the 1980s.
Dead person donates their islets of Langerhans (insulin producing cells). These are cloned and injected into a small plastic ‘teabag’ somewhere with good blood flow with bag holes big enough for red blood cells to take the glucose to those islets but too small for white blood cells to attack them as foreign cells. One inexpensive, small operation and diabetes is solved.