Driving from California through Arizona on the way home to Texas in August 1938, we made frequent stops because my 8-year-old brother said he had to go to the toilet. “Go see what is going on,” my mother directed me, then age 12. “We are stopping too often.”

I reported back that Johnny was peeing a lot, and it was like water. “Oh! I hope it's not diabetes like my cousin Norman,” my Mom replied. This was the first time I had heard the word diabetes. Later, she told us a brief story of 16-year-old cousin Norman, who had diabetes and had died in a coma in Connecticut while on the way to see a famous doctor in Boston, Mass., in 1919.

The day after we arrived home, my mother and brother visited our family doctor.

After Johnny came home from the hospital in Dallas, I learned to test his urine for sugar.

I was the resident chemist at our house because I had an amateur chemistry set from which I had made invisible ink, a chemical that smelled like rotten eggs, and some handsome dyes for cloth. I would put a teaspoon of a blue liquid called Benedict's solution into a test tube and add 10 drops of urine. Then, I'd place it in boiling water for 5 minutes. The solution might stay blue or it might turn green, yellow, orange, or brick red. Rarely, the solution stayed blue but had a red sediment at the bottom of the tube. Later, I became skilled enough to skip the boiling water and just hold the tube over a gas flame until a color developed. Rarely did it boil over; after all, I was a chemist. I learned that our favorite color was blue, for that meant no sugar in …