So many points that need addressing!
Contamination of food. In the US there is a big difference in the way food is produced, hormones, antibiotics, GM, also big differences in environmental, welfare regulation and certainly traceability. However Americans do survive all this, my own observation is that the main problem is obesity.
I too remember when chicken was a luxury, since the 1950s poultry and pigs have been hybridized so that separate bloodlines have been developed for meat and eggs. This enables chickens to convert food much more efficiently and grow faster, and therefore meat much more affordable.
The poultry and pig industries have become integrated, in many cases the farmer is paid a few pence per chicken or pig to manage the unit the supplying company does everything else, including marketing. There is no chance of flooding the market or poor conditions ( in the UK) everything is very strictly controlled.
The general public has no idea of the scale of the industry, the units are often in secluded places with strong security for disease control and because of action by animal rights lunatics.
Diabetes. That is certainly not specific to meat eating, the big risk is obesity, if you eat too much food, take too little exercise, become fat and lazy, you are a prime candidate for diabetes. If you eat a moderate quantity of a good quality mixed diet, diabetes is a very low risk, count your calories for yourself and your loved ones..