Objective: Despite the high prevalence of hypertension in patients with type 2 diabetes, the prevalence of primary aldosteronism in this population has not been determined.
Research design and methods: One hundred subjects with type 2 diabetes and resistant hypertension, defined as blood pressure > 140/90 mmHg despite the use of > or = 3 antihypertensive agents, were screened for primary aldosteronism. Screening was performed by measuring the plasma aldosterone (PAC)-to-plasma renin activity (PRA) ratio. Subjects with a PAC-to-PRA ratio > 30 ng x ml(-1) x h(-1) underwent confirmatory salt load testing. Diagnostic criteria included 24-h urine aldosterone > or = 12 microg during the 3rd day of the oral salt load or a PAC > or = 5 ng/dl after the 4-h intravenous saline load.
Results: Thirty-four subjects had a PAC-to-PRA ratio >30 ng x ml(-1) x h(-1). Fourteen subjects (14% [95% CI 7.2-20.8]) had a confirmed diagnosis of primary aldosteronism. Ninety-three patients were African Americans. There were no differences in age, glycemic control, and number of antihypertensive drugs between subjects with and without primary aldosteronism. Subjects with primary aldosteronism had lower serum potassium (3.7 +/- 0.4 vs. 4.0 +/- 0.4 mmol/l, P = 0.012), higher PAC (15.6 +/- 8 vs. 9.1 +/- 6 ng/dl, P = 0.0016), and higher PAC-to-PRA ratio (98 +/- 74 vs. 21 +/- 30 x ml(-1) x h(-1), P < 0.001) than patients without primary aldosteronism.
Conclusions: Primary aldosteronism is common in diabetic patients with resistant hypertension, with a prevalence of 14%. Our results indicate that diabetic subjects with poorly controlled hypertension who are taking > or = 3 antihypertensive drugs should be screened for primary aldosteronism.