Red Meat Intake and Glycemic and Insulinemic Risk Factors for Type 2 Diabetes: A Systematic Review and Meta-Analysis

Abstract

Abstract Objectives Results from observational studies have suggested an association of red meat intake with increased risk of type 2 diabetes (T2D). However, results from randomized controlled trials (RCTs) have not shown clear evidence to support a mechanistic link between red meat intake and T2D risk factors. The objective of this systematic review and meta-analysis was to evaluate the impact of red meat intake on markers of glucose tolerance, including fasting glucose and insulin, postprandial glucose and insulin, insulin sensitivity and glycated hemoglobin (HbA1c). Methods A systematic review and meta-analysis was conducted on RCTs evaluating the effect of red meat intake, compared to lower or no red meat intake, on markers of glucose tolerance in adults. A search of PubMed yielded 17 relevant RCTs. Pooled estimates were expressed as standardized mean differences (SMD) between the red meat intervention and the control intervention with less or no red meat. Results Compared to diets with little or no red meat intake, there was no significant impact of red meat intake on insulin sensitivity (SMD: −0.12; 95% CI: −0.43, 0.19), insulin resistance (SMD: 0.23; 95% CI: −0.22, 0.68), fasting glucose (SMD: 0.12; 95% CI: −0.06, 0.30), fasting insulin (SMD: 0.16; 95% CI: −0.10, 0.42) or HbA1c (SMD: 0.00; 95% CI: −0.42, 0.43). Red meat intake modestly, but significantly, reduced postprandial glucose (SMD: −0.46; 95% CI: −0.77, −0.16; P < 0.003) compared to diets with little or no red meat intake in a small number of studies (n = 3). However, there was no effect on postprandial insulin (SMD: −0.74; 95% CI: −1.64, 0.16). Conclusions The results of this meta-analysis suggest red meat intake does not impact several glycemic and insulinemic risk factors for T2D. Thus, it is unclear whether there is a causal relationship with red meat intake and T2D risk or if other confounding lifestyle factors may be driving the observed association. Further investigations are needed, particularly on other markers of glucose tolerance, such as pancreatic beta-cell function, to better understand whether a causal relationship exists between red meat intake and risk of T2D. PROSPERO Registration: CRD42020176059 Funding Sources This research was funded by Beef Checkoff.