Diabetes mellitus (DM) is one of the most prevalent diseases encountered by the primary care physician on a daily basis. Complications associated with DM can include nephropathy, neuropathy, and retinopathy ("microvascular complications"), along with cardiovascular disease (CVD), which can include myocardial infarction (MI) and strokes ("macrovascular complications"). In the 1990s, landmark clinical trials demonstrated that intensive glycemic control can reduce the risk of developing microvascular complications, but reduction in macrovascular complications with intensive glycemic control was not clearly demonstrated. At this point, intensive glycemic control became the standard of care (SOC). In the 2000s, additional trials evaluating the effect of intensive glycemic control in patients with type 2 diabetes mellitus (T2D) and established CVD, or risk factors for CVD, subsequently failed to identify a macrovascular benefit from intensive glycemic control, and one of the trials was terminated early because of an increase in the risk of mortality observed among patients assigned to receive intensive glycemic control. These results led to less strict glycemic targets being recommended in older patients, particularly those with established CVD. In 2007, everything changed after a report surfaced suggesting that rosiglitazone was associated with a significant increase in the risk of MI, as well as an increase in the risk of cardiovascular death that was of borderline significance. As a result, in 2008, the FDA mandated that all new diabetes medications must exclude an unacceptable level of risk for atherosclerotic cardiovascular disease (ASCVD) prior to drug approval, and thus undergo additional cardiovascular safety trials. Accordingly, through these trials, some of the newer agents, particularly sodium-glucose cotransporter-2 inhibitors (SGLT-2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA), were demonstrated to reduce the risk of major adverse cardiovascular events (MACEs), independent of their effect on glycemic control. These findings subsequently led to further trials to evaluate the effects of some of these therapies on the risk of chronic kidney disease (CKD) progression, as well as adverse heart failure-related outcomes. SGLT-2 inhibitors have been demonstrated to reduce the risk of CKD progression, as well as a reduction in the risk of cardiovascular death or hospitalization secondary to heart failure in patients with both reduced ejection and preserved ejection fractions. A trial evaluating the effects of GLP-1RA on CKD outcomes is ongoing. The aim of this narrative review article, compiled by identifying relevant studies via the utilization of PubMed, is to provide a broad overview over the various clinical trials and analyses that have led to current diabetes management guidelines, and ultimately, help guide primary care physicians in selecting therapies that will not only improve glycemic control and reduce the risk of microvascular complications, but also reduce the risk of macrovascular disease in their patients with T2D.
