Effect of low-dose spironolactone on resistant hypertension in type 2 diabetes mellitus: a randomized controlled trial in a sub-Saharan African population

BACKGROUND: Low-dose spironolactone has been proven to be effective for resistant hypertension in the general population, but this has yet to be confirmed in type 2 diabetic (T2DM) patients. We assessed the efficacy of a low-dose spironolactone on resistant hypertension in a sub-Saharan African population of T2DM patients from Cameroon. METHODS: This was a four-week single blinded randomized controlled trial in 17 subjects presenting with resistant hypertension in specialized diabetes care units in Cameroon. They were randomly assigned to treatment with a daily 25 mg of spironolactone (n = 9) or to an alternative antihypertensive regimen (n = 8), on top of any ongoing regimen and prevailing lifestyle prescriptions. They were seen at the start of the treatment, then 2 and 4 weeks later. The primary outcome was change in office and self-measured blood pressure (BP) during follow-up, and secondary outcomes were changes in serum potassium, sodium, and creatinine levels. RESULTS: Compared with alternative treatment, low-dose spironolactone was associated with significant decrease in office systolic BP (-33 vs. -14 mmHg; p = 0.024), and in diastolic BP (-14 vs. -5 mmHg; p = 0.006). After 1 month of spironolactone, all the patients were controlled based on BP below 130/80 mmHg, with significant office BP reduction from 158 ± 17/86 ± 11 to 125 ± 11/72 ± 8, vs. 158 ± 8/94 ± 8 to 144 ± 17/89 ± 12 mmHg in the alternative treatment group. There was no significant variation in sodium and creatinine levels in both groups, but a mild increase of potassium levels in the spironolactone group. INTERPRETATION: Add-on low-dose spironolactone was effective in reducing BP to optimal levels in T2DM Cameroonian patients despite mild increase in serum potassium. Trial registration ClinicalTrials.gov Identifier NCT02426099. Date of registration April 2015.