The Application of Sodium-Glucose Cotransporter 2 Inhibitors to Chronic Kidney Disease Stage 4

Abstract

To the Editor Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are re-versible inhibitors of SGLT2, leading to reduction of renal glucose reabsorption and decrease of plasma glucose, in an insulin-independent manner [1]. Possible anti-atherosclerotic effects beyond glucose lowering of SGLT2i can be predicted [2], and we previously showed that SGLT2i improve metabol-ic parameters including coronary risk factors [3, 4]. Actually, the EMPA-REG OUTCOME trial that examined the effect of empagliflozin in addition to standard of care in patients with type 2 diabetes and established cardiovascular (CV) diseases demonstrated a significant reduction in the incidence of CV death and heart failure hospitalization [5]. Recently, the CAN-VAS program reported that canagliflozin significantly reduced hospitalization for heart failure as compared with placebo by 33% as well as empagliflozin [6]. Further, the CVD-REAL study, the large multinational study, presented that treatment with SGLT2i was associated with a lower risk of hospitaliza-tion for heart failure and death as compared with other glucose lowering drugs [7]. Prevention of development of heart failure by SGLT2i has been attracting a lot of attention [8]. SGLT2 is expressed in the proximal tubule of kidney and mediates reabsorption of approximately 90% of the filtered glucose load [9]; therefore, SGLT2i are not recommended for use in patients with renal insufficiency. Our previous studies demonstrated that estimated glomerular filtration rate (eGFR) has an influence on the improvement in HbA1c [10, 11], and liver function by SGLT2i [10]. However, the EMPA-REG OUTCOME trial showed that empagliflozin significantly re-duced incident or worsening of nephropathy, progression to macroalbuminuria, doubling of serum creatinine level accom-panied by eGFR of ≤ 45 mL/min/1.73 m 2 and initiation of renal replacement therapy [12]. The CANVAS program also demon-strated that canagliflozin reduced progression to macroalbumi-nuria, and 40% reduction in eGFR, renal replacement therapy, or renal death [6]. Both the EMPA-REG OUTCOME trial and CANVAS program proposed the renal protective effect of SGLT2i. In the EMPA-REG OUTCOME trial, mean eGFR at baseline in low-eGFR group was almost 48 mL/min/1.73 m 2 , and the rate of patients with urinary albumin-to-creatinine ra-tio > 300 was 18%. In the CANVAS program, mean eGFR at baseline was 76 mL/min/1.73 m 2 , and the rate of patients with macroalbuminuria was 7.1%. Effects of SGLT2i on renal func-tion and proteinuria in patients with severe renal insufficiency such as chronic kidney diseases (CKD) stage 4 and nephrotic syndrome remain largely unknown. Here, we present a 36-year-old man with a long-standing history of type 2 diabetes (21 years) admitted for pneumonia and heart failure. He had a significant prior history of obesity, and CKD stage 4 and nephrotic syndrome due to diabetic ne-phropathy. Dapagliflozin, one of SGLT2i, successfully reduced his urine protein and body weight, and improved heart failure and exercise tolerance without any adverse effects. On admission, body height, weight and body mass index were 158.6 cm, 137.9 kg and 54.8 kg/m 2 , respectively. Fever, tachycardia (heart rate, 118 /min), hypoxemia (SpO 2 94% with 4 L oxygen) and tachypnea (respiratory rate, over 20/min) and abnormal findings of chest X-ray (cardiomegaly, pleural effu-sion and consolidation) suggested the existence of heart failure and pneumonia. Systolic and diastolic blood pressures were 168 and 95 mm Hg, respectively. His eGFR, serum creatinine, and daily urinary protein levels were 14 mL/min/1.73 m 2 , 4.7 mg/dL and 15.5 g/day, suggesting the existence of CKD stage 4 and nephrotic syndrome [13]. At 3 weeks before admission, plasma glucose and HbA1c levels were 254 mg/dL and 8.3%, respectively. He had been treated by liraglutide (0.9 mg/day), piogl-itazone (15 mg/day), insulin aspart (40, 20 and 24 U before breakfast, lunch and dinner, respectively) and insulin glargine (65 U at bedtime). We stopped the use of pioglitazone because of the development of heart failure, and started to use dapagli-flozin (5 mg/day) on day 4. Clinical course is shown in Figure 1. Body weight promptly decreased and body weight loss of over 20 kg was obtained during hospitalization. Serum creati-nine gradually decreased after a transient increase, and eGFR also gradually increased after a transient decrease. Urinary protein promptly decreased, and a significant reduction (-10.8 g/day) was obtained during hospitalization. Low plasma B-type natriuretic peptide (BNP) levels in obesity due to an increased clearance of active natriuretic