Management of Diabetes Associated with Nephrotic Syndrome: Therapeutic Potential of Dapagliflozin for Protracted Volume Retention

Nephroprotective Effects of Dapagliflozin in Patients with Type 2 Diabetes

Objective This study analyzed changes in the estimated glomerular filtration rate calculated using cystatin C (eGFRcys) and sodium excretion in the urine after administering dapagliflozin as an add-on therapy to conventional treatment for diabetes. Methods This was a single-center, single-group, prospective interventional study. Dapagliflozin was administered to improve the plasma glucose control in 30 subjects with type 2 diabetes mellitus (age 53±8 years old; 66.6% men). Blood and urine tests were performed before and 6 and 12 months after dapagliflozin administration. The daily sodium excretion was estimated with the Kawasaki formula using second-morning urine samples. Results The eGFRcys did not markedly differ before and 6 months after the dapagliflozin administration but was significantly increased after 12 months (p<0.001), and the estimated daily sodium excretion was also significantly increased (p<0.001 at 6 months and p=0.002 at 12 months). The systolic and diastolic blood pressures tended to decrease after administration. The HbA1c level after the administration of dapagliflozin tended to be lower in the T3 group, showing the smallest increase in changes in the estimated daily sodium excretion from baseline to 6 months (28.2-107.5 mEq/day), than in the combined groups of T1 (219.5-110.1 mEq/day) and T2 (101.4-28.9 mEq/day). In contrast, the eGFRcys was significantly higher in the combined groups of T1 and T2 than that in the T3 group at both 6 and 12 months (p=0.031 and p=0.007, respectively). Conclusions Add-on therapy with dapagliflozin increased the urinary sodium excretion and decreased the blood pressure even in the early phase of this therapy. Our results suggest that dapagliflozin add-on therapy may exert nephroprotective effects in subjects with type 2 diabetes mellitus.

Effects of the sodium-glucose cotransporter 2 inhibitor dapagliflozin on fluid distribution: A comparison study with furosemide and tolvaptan

AIM

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are an antihyperglycemic drug with diuretic properties. We recently reported that an SGLT2 inhibitor ameliorated extracellular fluid expansion with a transient increase in urinary Na⁺ excretion. However, the effects of SGLT2 inhibitors on fluid distribution in comparison to conventional diuretics remain unclear.

METHODS

Forty chronic kidney disease patients with fluid retention (average estimated glomerular filtration rate 29.2 ± 3.2 mL/min per 1.73 m² ) were divided into the SGLT2 inhibitor dapagliflozin (DAPA), loop diuretic furosemide (FR) and vasopressin V2 receptor antagonist tolvaptan (TLV). The body fluid volume was measured on days 0 and 7 using a bioimpedance analysis device.

RESULTS

In all three groups, body weight was significantly and similarly decreased, and urine volume numerically increased for 7 days. Bioimpedance analysis showed that the changes in intracellular water were similar, but that there were significant changes in the extracellular water (ECW) (DAPA -8.4 ± 1.7, FR -12.5 ± 1.3, TLV -7.4 ± 1.5%, P = 0.048). As a result, the change in the ratio of ECW to total body water in the DAPA group was significantly smaller than that in the FR group, but numerically larger than that in the TLV group (DAPA -1.5 ± 0.5, FR -3.6 ± 0.5, TLV -0.5 ± 0.4%, P < 0.001).

CONCLUSION

Sodium-glucose cotransporter 2 inhibitor DAPA predominantly decreased the ECW with a mild increase in urine volume, but the change in the ECW/total body water was smaller than that in patients treated with FR, and larger than that in patients treated with TLV, suggesting that the effects of SGLT2 inhibitors on fluid distribution may differ from those of conventional diuretics.

Unmasking a sustained negative effect of SGLT2 inhibition on body fluid volume in the rat

The chronic intrinsic diuretic and natriuretic tone of sodium-glucose cotransporter 2 (SGLT2) inhibitors is incompletely understood because their effect on body fluid volume (BFV) has not been fully evaluated and because they often increase food and fluid intake at the same time. Here we first compared the effect of the SGLT2 inhibitor ipragliflozin (Ipra, 0.01% in diet for 8 wk) and vehicle (Veh) in Spontaneously Diabetic Torii rat, a nonobese type 2 diabetic model, and nondiabetic Sprague-Dawley rats. In nondiabetic rats, Ipra increased urinary excretion of Na+ (UNaV) and fluid (UV) associated with increased food and fluid intake. Diabetes increased these four parameters, but Ipra had no further effect, probably because of its antihyperglycemic effect, such that glucosuria and, as a consequence, food and fluid intake were unchanged. Fluid balance and BFV, determined by bioimpedance spectroscopy, were similar among the four groups. To study the impact of food and fluid intake, nondiabetic rats were treated for 7 days with Veh, Ipra, or Ipra+pair feeding+pair drinking (Pair-Ipra). Pair-Ipra maintained a small increase in UV and UNaV versus Veh despite similar food and fluid intake. Pair-Ipra induced a negative fluid balance and decreased BFV, whereas Ipra or Veh had no significant effect compared with basal values. In conclusion, SGLT2 inhibition induces a sustained diuretic and natriuretic tone. Homeostatic mechanisms are activated to stabilize BFV, including compensatory increases in fluid and food intake.

Effects and Safety of Sodium Glucose Cotransporter 2 Inhibitors in Diabetes Patients With Drug-Refractory Advanced Heart Failure

BACKGROUND

This study aimed to investigate the effect and safety of sodium glucose cotransporter 2 inhibitors (SGLT2-Is) in patients with drug-refractory heart failure (HF).Methods and Results:In 12 diabetic patients with advanced HF, SGLT2-Is were added to the treatment regimen. At 6 months after administration, improvements in New York Heart Association class and reduction in B-type natriuretic peptide levels were observed, in particular in patients with high right atrial pressure. During follow-up, they had neither cardiac events nor adverse side effects.

CONCLUSIONS

SGLT2-Is may be useful and safe in diabetic patients with drug-refractory HF, in particular accompanied by right-sided HF.

Interaction Between the Sodium-Glucose-Linked Transporter 2 Inhibitor Dapagliflozin and the Loop Diuretic Bumetanide in Normal Human Subjects

Background

Dapagliflozin inhibits the sodium‐glucose–linked transporter 2 in the renal proximal tubule, thereby promoting glycosuria to reduce hyperglycemia in type 2 diabetes mellitus. Because these patients may require loop diuretics, and sodium‐glucose–linked transporter 2 inhibition causes an osmotic diuresis, we evaluated the diuretic interaction between dapagliflozin and bumetanide.

Methods and Results

Healthy subjects (n=42) receiving a fixed diet with ≈110 mmol·d⁻¹ of Na⁺ were randomized to bumetanide (1 mg·d⁻¹), dapagliflozin (10 mg·d⁻¹), or both for 7 days, followed by 7 days of both. There were no meaningful pharmacokinetic interactions. Na⁺ excretion increased modestly with the first dose of dapagliflozin (22±6 mmol·d⁻¹; P<0.005) but by more (P<0.005) with the first dose of bumetanide (74±7 mmol·d⁻¹; P<0.005), which was not significantly different from both diuretics together (80±5 mmol·d⁻¹; P<0.005). However, Na⁺ excretion with dapagliflozin was 190% greater (P<0.005) when added after 1 week of bumetanide (64±6 mmol·d⁻¹), and Na⁺ excretion with bumetanide was 36% greater (P<0.005) when added after 1 week of dapagliflozin (101±8 mmol·d⁻¹). Serum urate was increased 4% by bumetanide but reduced 40% by dapagliflozin or 20% by combined therapy (P<0.05).

Conclusions

First‐dose Na⁺ excretion with bumetanide and dapagliflozin is not additive, but the weekly administration of one diuretic enhances the initial Na⁺ excretion with the other, thereby demonstrating mutual adaptive natriuretic synergy. Combined therapy reverses bumetanide‐induced hyperuricemia. This requires further study in diabetic patients with hyperglycemia who have enhanced glycosuria and natriuresis with dapagliflozin.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00930865.

SGLT-2 Inhibitors in Heart Failure: Implications for the Kidneys

PURPOSE OF REVIEW

This review aims to summarize the renal effects of sodium-glucose transporter-2 (SGLT-2) inhibitors and their potential implications in heart failure pathophysiology.

RECENT FINDINGS

In patients with diabetes and established atherosclerosis, the SGLT-2 inhibitor empagliflozin versus placebo significantly reduced the rate of heart failure admissions with 35%. Moreover, empagliflozin slowed kidney disease progression and reduced the need for renal replacement therapy. SGLT-2 inhibitors inhibit proximal tubular sodium and chloride reabsorption, leading to increased nephron flux throughout the distal renal tubules, most notably at the level of the macula densa. Afferent arteriolar vasoconstriction is promoted through tubulo-glomerular feedback and reduces glomerular capillary hydrostatic pressure, relieving podocyte stress and explaining renal preservation. Further, plasma volume is contracted and natriuresis promoted without inducing neurohumoral activation. Finally, SGLT-2 inhibitors may improve endothelial function and energy metabolism efficiency. Together, these promising features place them as a potential novel treatment for heart failure.