Glucagon-like peptide-1 receptor agonists (GLP-1RAs, incretin mimetics) and dipeptidyl peptidase-4 inhibitors (DPP-4is, incretin enhancers) are glucose-lowering therapies with proven cardiovascular safety, but their effect on microvascular disease is not fully understood. Both therapies increase GLP-1 receptor agonism, which is associated with attenuation of numerous pathological processes that may lead to microvascular benefits, including decreased reactive oxygen species (ROS) production, decreased inflammation and improved vascular function. DPP-4is also increase stromal cell-derived factor-1 (SDF-1), which is associated with neovascularisation and tissue repair. Rodent studies demonstrate several benefits of these agents in the prevention or reversal of nephropathy, retinopathy and neuropathy, but evidence from human populations is less clear. For nephropathy risk in human clinical trials, meta-analyses demonstrate that GLP-1RAs reduce the risk of a composite renal outcome (doubling of serum creatinine, eGFR reduction of 30%, end-stage renal disease or renal death), whereas the benefits of DPP-4is appear to be limited to reductions in the risk of albuminuria. The relationship between GLP-1RAs and retinopathy is less clear. Many large trials and meta-analyses show no effect, but an observed increase in the risk of retinopathy complications with semaglutide therapy (a GLP-1RA) in the SUSTAIN-6 trial warrants caution, particularly in individuals with baseline retinopathy. Similarly, DPP-4is are associated with increased retinopathy risk in both trials and meta-analysis. The association between GLP-1RAs and peripheral neuropathy is unclear due to little trial evidence. For DPP-4is, one trial and several observational studies show a reduced risk of peripheral neuropathy, with others reporting no effect. Evidence in other less-established microvascular outcomes, such as microvascular angina, cerebral small vessel disease, skeletal muscle microvascular disease and autonomic neuropathies (e.g. cardiac autonomic neuropathy, gastroparesis, erectile dysfunction), is sparse. In conclusion, GLP-1RAs are protective against nephropathy, whereas DPP-4is are protective against albuminuria and potentially peripheral neuropathy. Caution is advised with DPP-4is and semaglutide, particularly for patients with background retinopathy, due to increased risk of retinopathy. Well-designed trials powered for microvascular outcomes are needed to clarify associations of incretin therapies and microvascular diseases. Graphical Abstract

Purpose of the Review: Glucagon-like peptide 1 (GLP-1) receptor agonists (RA) have transformed obesity and type 2 diabetes (T2D) management. Tirzepatide, the first dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) RA approved for both conditions, has paved the way for next-generation incretin-based therapies. Among these, triple agonists targeting GLP-1, GIP, and glucagon receptors represent a promising next step. This review outlines the rationale for their development and summarizes clinical trial data, focusing on retatrutide, the most advanced candidate. Recent Findings: Retatrutide is the first triple agonist (acting on GLP-1/GIP/glucagon receptors) with published phase 2 data in people with obesity as well as in people with T2D. Retatrutide achieved up to 24.2% mean weight loss after 48 weeks in individuals with obesity and 16.9% in those with T2D after 36 weeks. In the T2D study, HbA1c improved by 2.2%, with 82% of participants reaching HbA1c ≤ 6.5%. Retatrutide also improved multiple cardiometabolic parameters, including blood pressure, lipids, waist circumference, and liver fat (82% reduction in hepatic steatosis). Gastrointestinal symptoms were the most common side effects; no major safety concerns were observed. A comprehensive phase 3 program is ongoing to evaluate efficacy, safety, and cardiovascular/renal outcomes in people with obesity and/or T2D. Other unimolecular triple agonists and combination regimens involving tirzepatide with additional mono agonists are also in development. Summary: Retatrutide, a triple agonist now in phase 3 trials, has the potential to become the most effective pharmacological treatment for obesity while also offering substantial benefits in T2D management and other cardiometabolic risk factors.

To investigate the relationship between age at diagnosis of type 2 diabetes and the risk of macrovascular disease, heart failure, and microvascular disease. In August 2022, PubMed/EMBASE were searched for articles reporting (i) coronary artery disease, cerebrovascular disease, peripheral vascular disease, amputation; (ii) heart failure; and (iii) retinopathy, neuropathy, nephropathy (albuminuria, chronic kidney disease [CKD], end-stage renal disease) by age at diagnosis of type 2 diabetes. Random effects, non-linear dose-response meta-analysis was undertaken for each outcome to assess the association with age at diagnosis (40 years = reference), using both crude and maximally adjusted odds ratios separately, with and without adjustment for current age (age at sampling). We identified 42 articles (230,003 to 3,465,590 participants; 1035 to 391,140 events). Age at diagnosis was positively associated with the risk of macrovascular diseases, heart failure, and CKD, independent of current age, and negatively associated with retinopathy. For other microvascular outcomes, when adjusting for current age, a "reverse U" relationship was observed (peak risk = 55-60 years). Retinopathy was negatively associated with age at diagnosis, highlighting the importance of retinopathy screening in early-onset type 2 diabetes. The implications of other associations were unclear due to the heterogeneity in methodologies and findings.

To investigate associations of self-reported walking pace (SRWP) with relative and absolute risks of cause-specific mortality. In 391,652 UK Biobank participants recruited in 2006-2010, we estimated sex- and cause-specific (cardiovascular disease [CVD], cancer, other causes) mortality hazard ratios (HRs) and 10-year mortality risks across categories of SRWP (slow, average, brisk), accounting for confounders and competing risk. Censoring occurred in September 30, 2021 (England, Wales) and October 31, 2021 (Scotland). Over a median follow-up of 12.6 years, 22,413 deaths occurred. In women, the HRs comparing brisk to slow SRWP were 0.74 (95% CI: 0.67, 0.82), 0.40 (0.33, 0.49), and 0.29 (0.26, 0.32) for cancer, CVD, and other causes of death, respectively, and 0.71 (0.64, 0.78), 0.38 (0.33, 0.44), and 0.29 (0.26, 0.32) in men. Compared to CVD, HRs were greater for other causes (women: 39.6% [6.2, 72.9]; men: 31.6% [9.8, 53.5]) and smaller for cancer (-45.8% [-58.3, -33.2] and - 45.9% [-54.8, -36.9], respectively). For all causes in both sexes, the 10-year mortality risk was higher in slow walkers, but varied across sex, age, and cause, resulting in different risk reductions comparing brisk to slow: the largest were for other causes of death at age 75 years [women: -6.8% (-7.7, -5.8); men: -9.5% (-10.6, -8.4)]. Compared to slow walkers, brisk SRWP was associated with reduced cancer (smallest reduction), CVD, and other (largest) causes of death and may therefore be a useful clinical predictive marker. As absolute risk reductions varied across age, cause, and SRWP, certain groups may particularly benefit from interventions to increase SRWP.