Crucial role of kidney function in resistance to antihypertensive therapy in patients with diabetes mellitus

OBJECTIVES: Effective blood pressure (BP) control is difficult to achieve in diabetic patients. This study investigated factors that exacerbate resistance to antihypertensive medication in patients with diabetes. METHODS: Hypertensive patients with type 2 diabetes (n = 108, 67 ± 9 years) were subjected to a step-wise upward titration of medication (step 1, routine dose of angiotensin receptor blocker; step 2, routine doses of angiotensin receptor blocker and calcium channel blocker; step 3, step 1 + double dose of calcium channel blocker; step 4, double doses of angiotensin receptor blocker and calcium channel blocker; step 5, step 4 + routine dose of diuretic; step 6, step 5 + routine dose of β-blocker; step 7, step 6 + routine dose of α-blocker; step 8, step 6 + double dose of α-blocker) implemented with a target home BP of below 130/80 mmHg. The step number at which target BP was achieved was considered the amount of antihypertensive medications needed for BP control. RESULTS: All patients reached the target BP at step 4.0 ± 1.5. Multivariate regression analysis identified estimated glomerular filtration rate, but not measures of glycemic control, as an independent predictor of the number of drugs needed for BP control (P < 0.0001). CONCLUSION: The number of antihypertensive medications needed for BP control in patients with diabetes mellitus is largely dependent on estimated glomerular filtration rate. Impaired kidney function could produce resistance to antihypertensive therapy in diabetic patients.