George Minot gets his first insulin in January 1923

The US government’s contract price for 100 units of insulin dropped sharply from 1923 to 1925. The data is from congressional records authorizing the Veterans Bureau procurement to purchase Ileting (Lilly’s brand of insulin).
The relative price of insulin, compared to the Consumer’s Price Index. (From “The Discovery and Manufacture of Insulin” by Gene E. McCormick)

Insulin first reached George Minot in January 1923, fifteen months after the onset of his diabetes.  According to the statistics, about 40% of patients died within the first 15 months after diagnosis.  His restrictive diet undoubtedly pushed the odds in his favor.  Still, the diet was not a long term solution to diabetes.  Insulin was.  At the time, his weight was down to 120 pounds and his blood sugar was up to 240 mg/dl.  He kept working on his research, but he was constantly tired and irritable [inquisitive phys, p 128]. He was then on a diet of 1675 calories per day, slightly more than before but still not enough to sustain a person.  The higher calorie diet was meant to reduce the rate at which he was losing weight, but it came at a cost of higher blood sugar.  On January 12, 1923, George Minot had his first insulin injections, he got 6 units.  (His dose would be up to 40 units a few years later when insulin was plentiful.)  Within three
months, he had gained five pounds and kept his blood sugar under control.

The isoelectric precipitation process dramatically increased yields.  The yield of insulin, from isoelectric precipitation, is about 1600 units per pound of pancreas. The team of engineers at Eli Lilly had started off with a yield of 0.5 unit per pound, within a few months had raised the yield to 100 units per pound, and then finally arrived at 1600 units per pound.  (Two tons of pancreases provide about 8 ounces of pure insulin [Collection of Pancreas Glands by MV Williams, CSL.])  In a less than a year, an ox’s pancreas went from providing enough insulin for one person for one day to enough to provide for one person for several months.