In her early 20s, Karisa Hunt learned the hard lesson of what happens when someone rations life-preserving medication. Hunt was diagnosed with Type 1 diabetes as a 4-year-old and has been on insulin since then to help control her blood sugar levels. But while in college and feeling guilty for saddling her parents with high copays for the insulin, she started lowering her prescribed dosage. “It was a little less here, a little less there,” she recalled recently. It proved a life-altering decision, one that resulted in two surgeries in each eye and, ultimately, the complete loss of vision in her…