Meat consumption and incident type 2 diabetes: an individual-participant federated meta-analysis of 1·97 million adults with 100 000 incident cases from 31 cohorts in 20 countries, The Lancet Diabetes and Endocrinology, September 2024

Findings: Greater consumption of each of the three types of meat [unprocessed red meat, processed meat, poultry] was associated with increased incidence of type 2 diabetes.

Interpretation: The consumption of meat, particularly processed meat and unprocessed red meat, is a risk factor for developing type 2 diabetes across populations. These findings highlight the importance of reducing meat consumption for public health and should inform dietary guidelines.

Possible mechanisms:

Meat consumption could affect type 2 diabetes risk through different causal mechanisms that worsen insulin sensitivity, pancreatic β-cell function, or both.33

For example, red meat is rich in saturated fatty acids but low in polyunsaturated fatty acids, and switching from a diet rich in saturated fatty acids to one rich in polyunsaturated fatty acids was found to be associated with improved insulin resistance in a meta-analysis of short-term trials.43

Additionally, meat is characterised by its high protein content, and some research has indicated a potential association between a high intake of animal proteins and increased risk of type 2 diabetes.44–46

Another potential mechanism could be via trimethylamine N-oxide, a gut microbiota-dependent metabolite generated during the digestion of choline and l-carnitine, which are abundant in red meat, although the exact mechanism is yet to be established.47

Nitrate or nitrite additives and the formation of N-nitroso compounds during meat processing are associated with a higher risk of type 2 diabetes.48

Small-scale trials have indicated that advanced glycation end products—compounds generated when cooking meat products at high temperatures, such as frying or grilling—could contribute to oxidative stress, pro-inflammatory response, and subsequently insulin resistance.49–51

Meat can be a major source of iron in many populations, but long-term iron intake has been implicated in an increased risk of type 2 diabetes in observational studies52 and in Mendelian randomisation analysis.53