SGLT2 inhibitors in diabetic kidney disease: flat surrogates, real outcomes

Design

Systematic review and meta-analysis of 17 randomised trials

Population

29,192 adults with diabetic chronic kidney disease

Primary outcome

Renal surrogate markers (eGFR and urine albumin-to-creatinine ratio)

Effect

eGFR +0.25 mL/min/1.73m2 (95% CI -0.08 to 0.57) and UACR -31.6 mg/g (95% CI -137 to 74), both non-significant

This systematic review pooled 17 randomised trials of SGLT2 inhibitors in 29,192 adults with diabetic chronic kidney disease, grouping outcomes into renal surrogate markers, metabolic and haemodynamic measures, and safety.

The metabolic effects were clear: HbA1c fell by 0.40 percentage points, weight by 1.36 kg and systolic blood pressure by about 3 mmHg. The renal surrogate markers were not. Neither eGFR nor the urine albumin-to-creatinine ratio changed significantly over the short to medium term. Volume-depletion events were more common, while urinary tract infection was not significantly raised.

The authors are careful about what this means. Flat surrogate markers over months do not contradict the kidney and cardiovascular protection seen in large outcome trials, which count hard events over years. The practical message is unchanged: use these drugs for protection in diabetic kidney disease, and counsel on hydration rather than watching for a visible change in eGFR or albuminuria.

• Pooled from 17 randomised trials in 29,192 adults with diabetic chronic kidney disease.
• HbA1c fell by 0.40 percentage points, weight by 1.36 kg and systolic blood pressure by about 3 mmHg.
• eGFR and the urine albumin-to-creatinine ratio showed no significant short- to medium-term change.
• Volume-depletion events were more common (relative risk 1.36); urinary tract infection was not significantly raised.
• Check volume status and hydration when starting these drugs, especially alongside diuretics.

Why it matters

Flat eGFR and albuminuria over months do not mean the drugs are not working; the kidney benefit shows up as events over years.

Don't overread it

Neutral surrogate markers do not overturn the large outcome trials showing long-term kidney and heart protection.

The statistics, in plain English

The confidence intervals for eGFR (-0.08 to 0.57) and albuminuria (-137 to 74) both cross zero, so no real short-term effect on these markers was detected. That is not the same as no benefit: the proven protection comes from large trials counting hard events over years, which these surrogate measures do not capture.

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