Red meat consumption — whether processed or not — was linked to onset of type 2 diabetes in the U.S. according to a 2023 article in American Journal of Clinical Nutrition. The research was a long-term observational study by mostly Harvard-based scientists. Among the authors that might be familiar to you are Walter Willett, Frank Hu, and Frank Sacks. Click the link for the deets.
This doesn’t prove that red meat consumption causes diabetes. But if you enjoy a fair or high amount of red meat, you might benefit by cutting back, especially if diabetes runs in your family. I’d also suggest regular exercise and avoiding overweight and obesity to reduce your risks of type 2 diabetes. The author suggest red meat alternatives: nuts, legumes, dairy foods.
In the same journal issue is a commentary by Daan Kremer. Some snippets:
The current observational study is unlikely to end the discussion on whether red meat intake increases risk of type 2 diabetes and even less likely to end the epistemological debates on how to grade quality of observational evidence when many efforts are made to reduce bias and confounding.
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All in all, the study by Gu et al. may arguably be the best evidence to date on the relation between red meat intake and type 2 diabetes. Yet somehow, I feel that the books have not been closed.
Steve Parker, M.D.
Paleo Diabetic 
It’s an observational study which means it’s interesting and maybe useful but shouldn’t be taken as the truth.
I’m doing an observational study of myself because I’m a Type 2 Diabetic and it’s quite difficult to spot strong correlations between what I eat, the time I eat, the exercise (or not) I do and so on. This is not surprising as Diabetes is a syndrome.
As was pointed out above there are confounding factors to any observational study but that doesn’t mean we can’t garner some useful information as a springboard to further studies.