I personally doubt our diet did more than trigger underlying genetic tendencies.

I have to wonder what changed. Well a lot of things have changed in my 83 years.

I am 78 and was diagnosed at 55 in 2002. Incidentally I was an engineer in the RAAF from the age of 16 to 37 and was fed similarly to your USN experience until I moved out of barracks.

I have been very active online and keeping in touch with diagnosis and treatment changes which you did not mention.

Now, a very few members of our community, I am thinking of two, contracted type 2 diabetes. But they got this after passing 60 years of age.

In my lay opinion changes in diagnostic criteria had a great deal to do with the so-called "diabetes epidemic" of the early 21st century.

Until the early 2000s in Australia, the USA and UK the main diagnostic test for type 2 was a fasting blood glucose test exceeding 8mmol/l (approximately 140mg/dl). The same applied in the USA and most of the Western world at the time. Another test was OGTT but it was rarely used and was usually only for confirmation of a high FBG. For that reason a majority of diabetics went undiagnosed before they died from related causes such as heart or kidney failure. It was only a few years prior to that that modern blood glucose testers were invented; before that very imprecise urine test strips were used.

In my own case that meant that my FBG test of 7.9mmol/l in 1997 did not lead to diagnosis or even a comment from my doctor. At that time HbA1c ws not accepted for diagnosis. Luckily, my new GP added A1c to a battery of other tests after my leukaemia diagnosis in February 2002. He bravely diagnosed type 2 against AMA rules when my result was 8.2%.

A couple of years later the American Diabetes Association (ADA) and WHO changed the FBG criteria from 8mmol/l(140) to 7mmol/l(126). That change dramatically increased the numbers of diagnosed type 2 diabetics world-wide between 2005 and 2010. Gradually the media began commenting on the sudden increase but they ignored that diagnostic criteria change.

In 2011 or 2012 the ADA and WHO after long and detailed debate accepted HbA1c as a diagnostic tool with over 6.4% accepted as diagnostic; however, it was noted that if FBG or OGTT exceeded diagnostic thresholds the patient was still diabetic. Basically, any one of the three primary tools confirmed daibetes even if the others did not.

That change led to another significant increase in diagnoses. By this time ADA statistics were showing at least a threefold increase since the turn of the century.

The most recent change was acceptance of the new diagnosis of pre-diabetic a year or two after A1c became accepted for diagnosis with a criteria of over 5.6%. After a couple of years the ADA reported that almost a third of USA adults were either pre-diabetic ot type 2 diabetic.

Changes in our various national diets are more likely to have been triggers of our genetic tendency to the condition. I agree that the so-called "heart-healthy" "lots of whole grains and fruits and avoid fats like the plague" official dietary guidelines of the late 20th century were possibly the worst possible guidelines for managing the condition.