Meat consumption, particularly of processed meat and unprocessed red meat, is associated with a higher type 2 diabetes risk, suggests an analysis of data from 1.97m participants.
Global meat production has increased rapidly in recent decades and meat consumption exceeds dietary guidelines in many countries. Earlier research indicated that higher intakes of processed meat and unprocessed red meat are associated with an elevated risk of type 2 diabetes, but the results have been variable and not conclusive.
Poultry such as chicken, turkey, or duck is often considered to be an alternative to processed meat or unprocessed red meat, but fewer studies have examined the association between poultry consumption and type 2 diabetes.
To determine the association between consumption of processed meat, unprocessed red meat and poultry and type 2 diabetes, the team – led by researchers at the University of Cambridge – used the global InterConnect project to analyse data from 31 study cohorts in 20 countries. Their extensive analysis took into account factors like age, gender, health-related behaviours, energy intake and body mass index.
They found that the habitual consumption of 50 grams of processed meat a day, equivalent to two slices of ham, is associated with a 15% higher risk of developing type 2 diabetes in the next 10 years.
Eating 100 grams of unprocessed red meat a day – equivalent to a small steak – was associated with a 10% higher risk of type 2 diabetes.
Habitual consumption of 100 grams of poultry a day was associated with an 8% higher risk, but when further analyses were conducted to test the findings under different scenarios, the association for poultry consumption became weaker, whereas the associations with type 2 diabetes for each of processed meat and unprocessed meat persisted.
Professor Nita Forouhi of the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, and a senior author on the paper, said: “Our research provides the most comprehensive evidence to date of an association between eating processed meat and unprocessed red meat and a higher future risk of type 2 diabetes. It supports recommendations to limit the consumption of processed meat and unprocessed red meat to reduce type 2 diabetes cases.
“While our findings provide more comprehensive evidence on the association between poultry consumption and type 2 diabetes than was previously available, the link remains uncertain and needs to be investigated further.”
InterConnect uses an approach that allows researchers to analyse individual participant data from diverse studies, rather than being limited to published results.
This enabled the authors to include as many as 31 studies in this analysis, 18 of which had not previously published findings on the link between meat consumption and type 2 diabetes.
By including this previously unpublished study data the authors considerably expanded the evidence base and reduced the potential for bias from the exclusion of existing research.
Lead author Dr Chunxiao Li, also of the MRC Epidemiology Unit, said: “Previous meta-analysis involved pooling together of already published results from studies on the link between meat consumption and type 2 diabetes, but our analysis examined data from individual participants in each study. This meant that we could harmonise the key data collected across studies, such as the meat intake information and the development of type 2 diabetes.
“Using harmonised data also meant we could more easily account for different factors, like lifestyle or health behaviours, that might affect the association between meat and diabetes.”
Professor Nick Wareham, director of the MRC Epidemiology Unit, and a senior author on the paper said: “InterConnect enables us to study the risk factors for obesity and type 2 diabetes across many different countries and continents, helping to include populations that are under-represented in traditional meta-analyses.”
Most research studies on meat and type 2 diabetes have been conducted in USA and Europe, with some in East Asia. This research, published in The Lancet Diabetes & Endocrinology, included additional studies from the Middle East, Latin America and South Asia, and highlighted the need for investment in research in these regions and in Africa.
“Using harmonised data and unified analytic methods across nearly 2m participants allowed us to provide more concrete evidence of the link between consumption of different types of meat and type 2 diabetes than was previously possible,” added Wareham.
Study details
Meat consumption and incident type 2 diabetes: an individual-participant federated meta-analysis of 1.97 m adults with 100 000 incident cases from 31 cohorts in 20 countries.
Tom Bishop, Fumiaki Imamura, Soren Brage et al.
Published in The Lancet Diabetes & Endocrinology on 2024
Abstract
Summary
Background
Meat consumption could increase the risk of type 2 diabetes. However, evidence is largely based on studies of European and North American populations, with heterogeneous analysis strategies and a greater focus on red meat than on poultry. We aimed to investigate the associations of unprocessed red meat, processed meat, and poultry consumption with type 2 diabetes using data from worldwide cohorts and harmonised analytical approaches.
Methods
This individual-participant federated meta-analysis involved data from 31 cohorts participating in the InterConnect project. Cohorts were from the region of the Americas (n=12) and the Eastern Mediterranean (n=2), European (n=9), South-East Asia (n=1), and Western Pacific (n=7) regions. Access to individual-participant data was provided by each cohort; participants were eligible for inclusion if they were aged 18 years or older and had available data on dietary consumption and incident type 2 diabetes and were excluded if they had a diagnosis of any type of diabetes at baseline or missing data. Cohort-specific hazard ratios (HRs) and 95% CIs were estimated for each meat type, adjusted for potential confounders (including BMI), and pooled using a random-effects meta-analysis, with meta-regression to investigate potential sources of heterogeneity.
Findings
Among 1 966 444 adults eligible for participation, 107 271 incident cases of type 2 diabetes were identified during a median follow-up of 10 (IQR 7–15) years. Median meat consumption across cohorts was 0–110 g/day for unprocessed red meat, 0–49 g/day for processed meat, and 0–72 g/day for poultry. Greater consumption of each of the three types of meat was associated with increased incidence of type 2 diabetes, with HRs of 1·10 (95% CI 1·06–1·15) per 100 g/day of unprocessed red meat (I2=61%), 1·15 (1·11–1·20) per 50 g/day of processed meat (I2=59%), and 1·08 (1·02–1·14) per 100 g/day of poultry (I2=68%). Positive associations between meat consumption and type 2 diabetes were observed in North America and in the European and Western Pacific regions; the CIs were wide in other regions. We found no evidence that the heterogeneity was explained by age, sex, or BMI. The findings for poultry consumption were weaker under alternative modelling assumptions. Replacing processed meat with unprocessed red meat or poultry was associated with a lower 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.
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