Hyperkalaemia in people with diabetes: occurrence, risk factors and outcomes in a Danish population‐based cohort study

Aims To examine the incidence, risk factors and clinical outcomes of hyperkalaemia in people with diabetes in a real‐world setting. Methods Using Danish health registries, we identified a population‐based cohort of people with first‐time drug‐treated diabetes, in the period 2000−2012. First, the cumulative incidence of hyperkalaemia, defined as first blood test with potassium level >5.0 mmol/l after diabetes treatment initiation, was ascertained. Second, in a case–control analysis, risk factors were compared in people with vs without hyperkalaemia. Third, clinical outcomes were assessed among individuals with hyperkalaemia in a before–after analysis, and among people with and without hyperkalaemia in a matched cohort analysis. Results Of 68 601 individuals with diabetes (median age 62 years, 47% women), 16% experienced hyperkalaemia (incidence rate 40 per 1000 person‐years) during a mean follow‐up of 4.1 years. People who developed hyperkalaemia had a higher prevalence of chronic kidney disease [prevalence ratio 1.74 (95% CI 1.68−1.81)], heart failure [prevalence ratio 2.35 (95% CI 2.18−2.54)], use of angiotensin‐converting enzyme inhibitors [prevalence ratio 1.24 (95% CI 1.20−1.28)], use of spironolactone [prevalence ratio 2.68 (95% CI 2.48−2.88)] and potassium supplements [prevalence ratio 1.59 (95% CI 1.52−1.67)]. In people with diabetes who developed hyperkalaemia, 31% were acutely hospitalized within 6 months before hyperkalaemia, increasing to 50% 6 months after hyperkalaemia [before–after risk ratio 1.67 (95% CI 1.61−1.72)]. The 6‐month mortality rate after hyperkalaemia was 20%. Compared with matched individuals without hyperkalaemia, the hazard ratio for death was 6.47 (95% CI 5.81−7.21). Conclusions One in six newly diagnosed people with diabetes experienced a hyperkalaemic event, which was associated with severe clinical outcomes and death.