Metformin and SGLT2i as First-line Combination Therapy in Type 2 Diabetes: A Real-world Study With a Focus on Ethnicity

Abstract

Purpose: Suboptimal glucose control early in the diagnosis of type 2 diabetes (T2D) is strongly associated with subsequent morbidity and mortality, termed the 'glycaemic legacy'. Additionally, it is known that Asian and Black individuals are at increased risk of T2D, and its associated complications compared to their White counterparts. However, ethnicity does not currently feature in the treatment algorithm of T2D, unlike in other cardiovascular disease states such as hypertension. We therefore sought to evaluate the real-world impact of early intensive treatment with combination therapy on cardiorenal outcomes compared to standard treatment in T2D, with a focus on ethnicity.

Methods: We performed a retrospective cohort study of all patients aged 18 or over with T2D using the TriNetX platform. TriNetX is a global collaborative network providing access to real time, anonymised medical records. We included patients who were initiated with Metformin and an SGLT2i within one month of diagnosis of T2D and compared this cohort with individuals who received Metformin only for a period of at least 1 year. We evaluated cardiovascular and renal outcomes at three years and stratified by ethnicity. We excluded individuals with a personal history of an outcome of interest.

Findings: We identified 49,651 individuals with T2D who were treated with Metformin and an SGLT2i and 1,028,806 patients with T2D who were treated with Metformin alone. A total of 98,094 individuals were included in the core analysis. The Metformin only group had a greater risk of mortality (RR 1.44, [95% CI 1.34-1.55], P<0.0001), CKD (RR 1.10, [95% CI 1.04-1.16], P = 0.0004), diabetic nephropathy (RR 1.06, [95% CI 1.01-1.12], P = 0.0239), heart failure (RR 1.13, [95% CI 1.07-1.21], P < 0.0001) and hospitalisation (RR 1.24, [95% CI 1.21-1.27], P < 0.0001) compared to individuals treated with Metformin and SGLT2i. Black individuals had a reduced risk of mortality (RR 0.71, [95% CI 0.55-0.92], P = 0.0099) and IHD (RR 0.73, [95% CI 0.64-0.84], P < 0.0001) compared to White individuals. Asian individuals had a reduced risk of heart failure (RR 0.61, [95% CI 0.41-0.91], P = 0.0134) and hospitalisation (RR 0.76, [95% CI 0.66-0.87], P = 0.0001) compared to White individuals.

Implications: Initial combination treatment within the first year of T2D diagnosis confers favourable cardio-metabolic outcomes when compared to standard therapy, even in patients without established cardiovascular disease. Black and Asian individuals in particular demonstrate a greater degree of benefit compared to White individuals. Further prospective studies with a focus on ethnicity are now required to validate these findings.

Keywords: Cardiovascular; Metformin; Mortality; Outcomes; SGLT2 inhibitor; Type 2 diabetes.