What are the complications associated with sodium‑glucose cotransporter‑2 (SGLT2) inhibitor therapy?

Complications of SGLT2 Inhibitor Use

SGLT2 inhibitors are associated with several manageable complications, most commonly genital mycotic infections (6% vs 1% placebo), with rare but serious risks including euglycemic diabetic ketoacidosis (particularly in insulin-requiring patients), volume depletion, and Fournier gangrene. 1

Common and Manageable Complications

Genital Mycotic Infections (Most Common)

• Incidence: 6% with SGLT2i vs 1% with placebo 1
• Higher risk: Women (10-15%), uncircumcised men, those with prior infections 2
• Management: Most cases are easily treated with antifungal therapy without requiring drug discontinuation 2
• Prevention: Daily hygienic measures can reduce risk 1

Urinary Tract Infections

• Evidence is less consistent than for genital infections 3
• Risk appears modest, particularly in non-diabetic heart failure/CKD patients 3

Serious but Rare Complications

Euglycemic Diabetic Ketoacidosis (Critical to Recognize)

• Incidence: 0.1% overall 2, but 4% in type 1 diabetes (where SGLT2i are contraindicated) 4
• Key feature: Can occur with normal or minimally elevated glucose (<200 mg/dL or <14 mmol/L) 2
• Highest risk patients: Those requiring insulin therapy 1

Risk mitigation strategies:

• Maintain at least low-dose insulin in insulin-requiring patients 1
• Withhold SGLT2i during: prolonged fasting, surgery, critical illness, dehydrating illness 5, 2
• Monitor blood or urine ketones when symptomatic 1
• Educate patients on symptoms: shortness of breath, nausea, vomiting, abdominal pain, confusion, anorexia, excessive thirst, lethargy 2
• Discontinue immediately if ketoacidosis develops and seek urgent medical attention 1

Fournier Gangrene

• Severe necrotizing fasciitis of the perineum
• Extremely rare but has been reported 1
• Requires immediate drug discontinuation and urgent surgical intervention

Metabolic and Renal Effects

Reversible eGFR Decline (Expected, Not Harmful)

• Initial decline: 3-5 mL/min/1.73 m² in first 4 weeks 5
• Clinical significance: This is a hemodynamic effect, NOT kidney injury 1
• Management: Generally does NOT require discontinuation 1, 5
• Long-term benefit: SGLT2i actually protect against acute kidney injury 1
• Continue therapy even if eGFR falls below initiation threshold unless not tolerated or dialysis initiated 1

Hypovolemia and Volume Depletion

• Absolute risk is low, especially at lower eGFR 1
• Management approach:
  • Background diuretic adjustment generally NOT required at initiation 1
  • May be prudent in select patients at high risk 1
  • Exercise caution when combining with ARNIs and loop diuretics 2
  • Follow-up to reassess volume status is important 1

Hypoglycemia

• Risk is low in absence of concomitant insulin or secretagogue therapy 2
• Background glucose-lowering agents may need adjustment 1
• Particularly low risk at lower eGFR levels 1

Controversial or Uncertain Risks

Lower Limb Amputation

• Canagliflozin-specific concern: Increased risk observed (RR 1.94,95% CI 1.25-3.0) in elderly patients 6
• Risk appears comparable to DPP-4 inhibitors but with some trend vs GLP-1 RAs 3
• Clinical approach: Exercise caution in patients with peripheral artery disease 3

Bone Fractures

• No conclusive evidence linking SGLT2i to increased fracture risk 3
• Risk similar between SGLT2i and placebo in elderly patients 6

Acute Kidney Injury

• Despite initial concerns, SGLT2i actually reduce AKI risk (RR 0.73,95% CI 0.62-0.87 in elderly) 6
• The initial eGFR dip should not be confused with AKI 1

Absolute Contraindications

• Type 1 diabetes (not FDA-approved; high DKA risk) 2, 4
• Active diabetic ketoacidosis 1
• Dialysis (limited evidence, though dapagliflozin package insert restriction removed after FDA review) 5

Clinical Context: Risk-Benefit Balance

The complications of SGLT2i must be weighed against their proven mortality and morbidity benefits: significant reductions in cardiovascular death (RR 0.63), heart failure hospitalization (RR 0.65), all-cause mortality (RR 0.71), and kidney disease progression 1. The absolute risks of serious complications are low, while the benefits on hard outcomes are substantial and consistent across trials.

Key pitfall to avoid: Do not discontinue SGLT2i for the expected initial eGFR decline of 3-5 mL/min/1.73 m² - this is a hemodynamic effect that does not represent kidney injury and resolves with continued therapy 1, 5.