After age 30, the body does not create any new beta cells.

Some fascinating information on Beta cells and how above ground nuclear bomb testing played a part in diabetes knowledge.

"Beta cells, which make insulin in the human body, do not replicate after the age of 30, indicating that clinicians may be closer to better treating diabetes. Type 1 diabetes is caused by a loss of beta cells by auto-immunity while type 2 is due to a relative insufficiency of beta cells. Whether beta cells replicate after birth has remained an open issue, and is critically important for designing therapies for diabetes.

By using radioactive carbon-14 produced by above-ground nuclear testing in the 1950s and '60s, researchers have determined that the number of beta cells remains static after age 30.

Lawrence Livermore National Laboratory scientist Bruce Buchholz, with collaborators from the National Institutes of Health, used two methods to examine adult human beta cell turnover and longevity.

Using LLNL's Center for Accelerator Mass Spectrometry, Buchholz measured the amount of carbon 14 in DNA in beta cells and discovered that after age 30, the body does not create any new beta cells, thus decreasing the capacity to produce insulin as a person ages. Carbon 14 atmospheric concentration levels remained relatively stable until the Cold War, when above-ground nuclear bomb tests caused a sharp increase, or peak, which decreased slowly after the end of above-ground testing in 1963. This spike in carbon 14 in the atmosphere serves as a chronometer of the past 57 years.

Type 2 diabetes (often called adult onset diabetes) is common in older people whose ability to secrete sufficient insulin to regulate blood sugar deteriorates as they age and is often due to increased demand in obese people.

"It could be due to loss of beta cells with age," Buchholz said. "The body doesn't make new ones in adulthood and there might not be enough cells to control blood sugar."

Information from here. https://www.llnl.gov/news/insulin-creating-cell-research-may-lead-better-diabetes-treatment

Interesting - but I've also read some competing information - that a major difference between nondiabetics and diabetics or future diabetics is that the former can regrow beta cells more effectively while the latter can't.

This explains obese nondiabetics and pregnant women who don't suffer from gestational diabetes because they *can* grow more beta cells to deal with the increased demand for insulin, and the fact that gestational diabetics are prone to become full time diabetics later in lfe.

There's little doubt that pancreases wear out earlier than many other tissues, and there's a theory that everyone will become diabetic eventually - but at age 150 after they already died from something else - but I strongly suspect genetic factors dictate how soon and how quickly this occurs. Maybe some people can and some can't continue this process after 30.

Off topic-ish, I used to know someone who'd worked at Ground Zero in some of the original nuclear tests. He ended up with a weird kind of adult onset Type 1, almost certainly due to radiation damage, where he alternated between massive hypos requiring ambulance runs to the hospital and equally massive liver dumps where his liver emitted every scrap of glycogen it contained non-stop until it was exhausted.

Despite this I think he lasted into his seventies.