A diet rich in red meat is associated with an increased risk of type 2 diabetes. In three long-standing cohorts from the US, adults who increased their intake by half a serving a week in a four year period had an increased risk of diabetes over the next four years (pooled hazard ratio 1.48, 95% CI 1.37 to 1.59).
Cutting intake took longer to make a difference, but risk of diabetes fell by 14% over 12-16 years of follow-up (hazard ratio 0.86, 0.80 to 0.93).
Eating more red meat tends to increase body weight, and this explained some but not all of the association between red meat and diabetes in this study. All analyses were adjusted for other changes in lifestyle and quality of diet.
If red meat does cause diabetes directly (still a big if), saturated fat is one potential culprit. Adipocytes stuffed with saturated fat are pro-inflammatory, and this has a knock-on effect on insulin resistance through oxidative stress.
The colour of meat, which is determined by the content of myoglobin and haemoglobin, is probably irrelevant to the risk of diabetes, and we should move away from classifying meat as red or otherwise.
It would seem that fatty meat, not red meat, is the problem.
Source: JAMA Intern Med 2013; doi:10.1001/jamainternmed.2013.6633.