By late December 1921, Banting was ready for experimenting with insulin in human patients. He first gave some insulin orally to a friend and medical school classmate of his, Dr Joseph Gilchrist. Just as in the dogs, oral delivery had no effect. No change in the blood sugar was noted. Gilchrist had developed diabetes in 1917, and had been on a starvation diet for four years. His life expectancy was less than a year at the time.
Other patients were even closer to death. Leonard Thompson, a 12 year old boy had been in the Toronto General Hospital for a month. He was in the final stages of diabetes. He couldn’t walk, he weighed only 65 pounds. He probably had no more than a month or two to live.
Leonard Thompson had been a healthy boy until December 1919. His parents noticed that he was wetting the bed at night, a problem he didn’t previously experience. Clinically, this is known as polyuria. A month later, a urine test showed the presence of sugar (glycosuria). He began to lose weight. He had to urinate more and more frequently. Finally, his doctor recommended that he be admitted to the hospital.
Upon admission to the hospital, his examination showed that he weighed only 65 pounds. His hair was falling out, his breath smelled of acetone, and his blood sugar was at 580 mg/dL. All classic signs of diabetes.
Banting and Best made their second human attempt on January 11, 1922 with Leonard Thompson. They injected a crude extract that Best prepared from fetal cow pancreases. They first tested part of the batch on a dog to gauge its potency, then gave the boy half the dose the dog would need. This solution was not very pure. They needed to inject Leonard with 15 ml of the extract. 15 ml is a lot of liquid to inject into a person. They split it into two, and injected equal amounts in each buttock.
The results were not spectacular. Thompson’s blood sugar dropped slightly from 440 mg/dL to 320 mg/dL, but it was still dangerously high. They also noted side effects. One of the injection sites developed an abscess, caused by impurities in the insulin. Diabetic patients would eventually need to take multiple shots per day, and abscesses were a problem that plagued them for decades.