CARDIOVASCULAR MEDICINE

Effect of diabetes on serum potassium concentrations in acute coronary syndromes

K Foo¹, N Sekhri¹, A Deaner², C Knight², A Suliman¹, K Ranjadayalan¹, A D Timmis³

¹ Department of Cardiology, Newham HealthCare NHS Trust, London, UK
² Department of Cardiology Barking Havering and Redbridge NHS Trust, Essex, UK
³ Department of Cardiology, London Chest Hospital, Barts London NHS Trust, London, UK

Correspondence to:
Correspondence to:
Professor A D Timmis, London Chest Hospital, Bonner Road, London E2 9JX, UK;
timmis{at}lch.demon.co.uk

Objectives: To compare serum potassium concentrations in diabetic and non-diabetic patients in the early phase of acute coronary syndromes.

Background: Acute phase hypokalaemia occurs in response to adrenergic activation, which stimulates membrane bound sodium-potassium-ATPase and drives potassium into the cells. It is not known whether the hypokalaemia is attenuated in patients with diabetes because of the high prevalence of sympathetic nerve dysfunction.

Methods: Prospective cohort study of 2428 patients presenting with acute coronary syndromes. Patients were stratified by duration of chest pain, diabetic status, and pretreatment with ß blockers.

Results: The mean (SD) serum potassium concentration was significantly higher in diabetic than in non-diabetic patients (4.3 (0.5) v 4.1 (0.5) mmol/l, p < 0.0001). Multivariate analysis identified diabetes as an independent predictor of a serum potassium concentration in the upper half of the distribution (odds ratio 1.66, 95% confidence interval 1.38 to 2.00). In patients presenting within 6 hours of symptom onset, there was a progressive increase in plasma potassium concentrations from 4.08 (0.46) mmol/l in patients presenting within 2 hours, to 4.20 (0.47) mmol/l in patients presenting between 2–4 hours, to 4.24 (0.52) mmol/l in patients presenting between 4–6 hours (p = 0.0007). This pattern of increasing serum potassium concentration with duration of chest pain was attenuated in patients with diabetes, particularly those with unstable angina. Similar attenuation occurred in patients pretreated with ß blockers.

Conclusion: In acute coronary syndromes, patients with diabetes have significantly higher serum potassium concentrations and do not exhibit the early dip seen in non-diabetics. This may reflect sympathetic nerve dysfunction that commonly complicates diabetes.

Keywords: diabetes; serum potassium; acute coronary syndromes

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