Does background metformin therapy influence the cardiovascular outcomes with SGLT-2 inhibitors in type 2 diabetes?

Sodium-Glucose Co-transporter 2 Inhibitors Versus Metformin as the First-Line Treatment for Type 2 Diabetes: Is It Time for a Revolution?

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as a promising therapeutic option for hyperglycemia and its complications. However, metformin remains the first-line pharmacological treatment in most algorithms for type 2 diabetes (T2D). Although metformin is generally believed to exert positive effects on cardiovascular (CV) outcomes, relevant data are mainly observational and potentially overinterpreted. Yet, it exerts numerous pleiotropic actions that favorably affect metabolism and diabetes comorbidities. CV outcome trials have demonstrated cardiorenal protection with SGLT2i among people at high CV risk and mostly on concomitant metformin therapy. However, post hoc analyses of these trials suggest that the cardiorenal effects of gliflozins are independent of background treatment and consistent across the full spectrum of CV risk. Considering the importance of addressing hyperglycemia as a means of preventing diabetic complications and significant knowledge gaps, particularly regarding the cost-effectiveness of SGLT2i in drug-naïve populations with T2D, the position of metformin in the management of people with diabetes at low CV risk remains solid for the moment. On the other hand, available evidence-despite its limitations-suggests that specific groups of people with T2D, particularly those with heart failure and kidney disease, could probably benefit more from treatment with SGLT2i. This narrative mini-review aims to discuss whether current evidence justifies the use of SGLT2i as the first-line treatment for T2D.

Cardiovascular benefits of SGLT2 inhibitors in type 2 diabetes, interaction with metformin and role of erythrocytosis: a self-controlled case series study

Background

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have proven cardiovascular benefits in patients with type 2 diabetes (T2D). This self-controlled case series study aims to evaluate whether metformin use and SGLT2i-associated erythrocytosis influence its cardiovascular benefits.

Methods

T2D patients with metformin and/or SGLT2i prescriptions between 2015 and 2020 were identified from the Hong Kong population. Study outcomes were composite cardiovascular diseases (CVD), coronary heart disease (CHD), hospitalisation for heart failure (HHF), stroke, and erythrocytosis. Risk periods were patient-time divided into four mutually exclusive windows: (i) ‘baseline period’ of metformin use without SGLT2i; (ii) pre-SGLT2i period; (iii) exposure to SGLT2i without metformin; and (iv) exposure to the drug combination. Another SCCS model was applied to evaluate the association between erythrocytosis and cardiovascular outcomes regarding SGLT2i exposure. Four mutually exclusive risk periods included (i) SGLT2i exposure with erythrocytosis; (ii) SGLT2i exposure without erythrocytosis; (iii) absence of SGLT2i exposure with erythrocytosis; and (iv) absence of SGLT2i exposure without erythrocytosis. Incidence rate ratios (IRR) of events at different risk periods were estimated using conditional Poisson regression model.

Results

Among 20,861 patients with metformin and/or SGLT2i prescriptions, 2575 and 1700 patients with events of composite CVD and erythrocytosis were identified, respectively. Compared to metformin use without SGLT2i, SGLT2i initiation was associated with lower risks of composite CVD, CHD, and HHF—regardless of the presence (CVD: IRR = 0.43, 95% CI 0.37–0.51; CHD: IRR = 0.44, 95% CI 0.37–0.53; HHF: IRR = 0.29, 95% CI 0.22–0.40; all p < 0.001) and absence of concomitant metformin (CVD: IRR = 0.31, 95% CI 0.20–0.48; CHD: IRR = 0.38, 95% CI 0.25–0.59; HHF: IRR = 0.17, 95% CI 0.09–0.31; all p < 0.001); while SGLT2i was neutral on stroke risk. Compared to metformin-SGLT2i combination, exposure to SGLT2i alone was associated with comparable risks of all cardiovascular outcomes (all p > 0.05). Incidence rates of erythrocytosis at baseline, SGLT2i without and with metformin use periods were 0.75, 3.06 and 3.27 per 100 person-years, respectively. SGLT2i users who developed erythrocytosis had lower risk of HHF (IRR = 0.38, 95% CI 0.14–0.99, p = 0.049) than those who did not.

Conclusions

Our real-world data suggested that SGLT2i-associated cardiovascular benefits were not attenuated by metformin use. Further studies will delineate the role of erythrocytosis as a surrogate marker of SGLT2i-associated cardiovascular benefit in reducing HHF.

Insulin treatment in patients with diabetes mellitus and heart failure in the era of new antidiabetic medications

BACKGROUND

Coexistent heart failure (HF) and diabetes mellitus (DM) are associated with marked morbidity and mortality. Optimizing treatment strategies can reduce the number and severity of events. Insulin is frequently used in these patients, but its benefit/risk ratio is still not clear, particularly since new antidiabetic drugs that reduce major adverse cardiac events (MACEs) and renal failure have recently come into use. Our aim is to compare the clinical effects of insulin in a real-world setting of first-time users, with sodium-glucose cotransporter-2 inhibitor (SGLT-2i), glucagon-like peptide-1 receptor agonist (GLP-1RA) and the other antihyperglycemic agents (other-AHAs).

METHODS

We used the administrative databases of two Italian regions, during the years 2010-2018. Outcomes in whole and propensity-matched cohorts were examined using Cox models. A meta-analysis was also conducted combining the data from both regions.

RESULTS

We identified 34 376 individuals ≥50 years old with DM and HF; 42.0% were aged >80 years and 46.7% were women. SGLT-2i and GLP-1RA significantly reduced MACE compared with insulin and particularly death from any cause (SGLT-2i, hazard ratio (95% CI) 0.29 (0.23 to 0.36); GLP-1RA, 0.482 (0.51 to 0.42)) and first hospitalization for HF (0.57 (0.40 to 0.81) and 0.67 (0.59 to 0.76)).

CONCLUSIONS

In patients with DM and HF, SGLT-2i and GLP-1RA significantly reduced MACE compared with insulin, and particularly any cause of death and first hospitalization for HF. These groups of medications had high safety profiles compared with other-AHAs and particularly with insulin. The inadequate optimization of HF and DM cotreatment in the insulin cohort is noteworthy.

The risk trajectory of different cardiovascular morbidities associated with chronic kidney disease among patients with newly diagnosed diabetes mellitus: a propensity score-matched cohort analysis

Background

Chronic kidney disease (CKD) introduces an increased cardiovascular risk among patients with diabetes mellitus (DM). The risk and tempo of cardiovascular diseases may differ depending upon their type. Whether CKD differentially influences the risk of developing each cardiovascular morbidity in patients with newly diagnosed DM remains unexplored.

Methods

We identified patients with incident DM from the Longitudinal Cohort of Diabetes Patients (LCDP) cohort (n = 429,616), and uncovered those developing CKD after DM and their propensity score-matched counterparts without. After follow-up, we examined the cardiovascular morbidity-free rates of patients with and without CKD after DM, followed by Cox proportional hazard regression analyses. We further evaluated the cumulative risk of developing each outcome consecutively during the study period.

Results

From LCDP, we identified 55,961 diabetic patients with CKD and matched controls without CKD. After 4.2 years, patients with incident DM and CKD afterward had a significantly higher risk of mortality (hazard ratio [HR] 1.1, 95% confidence interval [CI] 1.06–1.14), heart failure (HF) (HR 1.282, 95% CI 1.19–1.38), acute myocardial infarction (AMI) (HR 1.16, 95% CI 1.04–1.3), and peripheral vascular disease (PVD) (HR 1.277, 95% CI 1.08–1.52) compared to those without CKD. The CKD-associated risk of mortality, HF and AMI became significant soon after DM occurred and remained significant throughout follow-up, while the risk of PVD conferred by CKD did not emerge until 4 years later. The CKD-associated risk of ischemic, hemorrhagic stroke and atrial fibrillation remained insignificant.

Conclusions

The cardiovascular risk profile among incident DM patients differs depending on disease type. These findings can facilitate the selection of an optimal strategy for early cardiovascular care for newly diagnosed diabetic patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01279-6.