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

Titration of telmisartan, but not addition of amlodipine, reduces urine albumin in diabetic patients treated with telmisartan-diuretic

OBJECTIVES

Microalbuminuria is closely associated with an increased risk of renal and cardiovascular adverse outcomes. The present study tested the hypothesis that titration of telmisartan reduces urinary excretion of albumin more than does addition of amlodipine in patients treated with a standard dose of telmisartan combined with a low-dose diuretic for the same degree of blood pressure (BP) reduction.

METHODS

Hypertensive patients with type 2 diabetes mellitus and microalbuminuria under treatment with a combination of a standard dose of telmisartan (40 mg/day) and trichlormethiazide (1 mg/day) were randomly assigned to receive either an increased dose of telmisartan (80 mg/day) combined with trichlormethiazide [increased dose angiotensin receptor blocker (ARB) group, n = 20] or a combination consisting of telmisartan (40 mg/day), trichlormethiazide, and amlodipine (5 mg/day) (triple combination group, n = 20) for 6 months. The primary endpoint was a reduction in urinary albumin levels.

RESULTS

Although BP was reduced to a similar extent by the two regimens, patients receiving the increased dose ARB showed a higher reduction in urinary albumin (-37.4 ± 16.9%) than those on the triple combination regimen (-8.9 ± 23.7%; P < 0.0001). The reduction in urinary albumin was correlated with the drop in BP in the latter group, but not in the increased dose ARB group.

CONCLUSION

Uptitration of telmisartan more effectively reduces urinary albumin than addition of amlodipine in hypertensive patients with diabetes treated with a combination of telmisartan and diuretic for the same degree of BP reduction.

Kidney-protective effects of azelnidipine versus a diuretic in combination with olmesartan in hypertensive patients with diabetes and albuminuria: a randomized study

BACKGROUND

A thiazide diuretic used in combination with benazepril is superior to amlodipine plus benazepril in reducing albuminuria in hypertensive patients with diabetes. However, calcium channel blockers have diverse characteristics. Thus, we investigated whether combining an angiotensin receptor blocker with either azelnidipine or a thiazide diuretic produced similar reductions in albuminuria in hypertensive diabetic patients for the same levels of blood pressure achieved.

METHODS

Hypertensive patients with type 2 diabetes and albuminuria (30-600 mg/g creatinine) under antihypertensive treatment (mean age 67.0±7.6 years) were instructed to stop all antihypertensive treatment and take a combination of olmesartan (20 mg/day) and amlodipine (5 mg/day) for 3 months (run-in period). Then, patients were randomly assigned to receive either olmesartan plus azelnidipine (16 mg/day; n=71) or olmesartan plus trichlormethiazide (1 mg/day; n=72) for an additional 6 months. The primary end point was urinary excretion of albumin at 6 months after randomization.

RESULTS

At the time of randomization, urinary albumin was 116.0 and 107.8 mg/g creatinine (geometric mean) in the azelnidipine and diuretic arms, respectively, and was reduced to a similar extent [79.8 (95% confidence interval 66.4-96.0) and 89.7 (74.6-107.7) mg/g creatinine, respectively, after adjustment for baseline values]. Blood pressure did not differ between the two groups throughout the study period.

CONCLUSIONS

Azelnidipine is equally effective as a thiazide diuretic in reducing urinary albumin when used in combination with olmesartan.

Aggressive blood pressure-lowering therapy guided by home blood pressure monitoring improves target organ damage in hypertensive patients with type 2 diabetes/prediabetes

The authors tested the hypothesis that an aggressive antihypertensive treatment is beneficial in protecting against target organ damage (TOD) in patients with type 2 diabetes/prediabetes. The authors enrolled 60 patients with uncontrolled hypertension and diabetes/prediabetes and performed clinic, home, and ambulatory blood pressure (BP) monitoring. Irbesartan, amlodipine, and indapamide were used according to a titration schedule from step 1 to 5 for target home BP level ≤125/75 mm Hg. The flow-mediated vasodilation (FMD), radial augmentation index (AI), pulse wave velocity (PWV), and urinary albumin excretion ratio (UACR), as a surrogate marker of TOD, were measured at baseline and 6 months. Compared with baseline, clinic, home, and ambulatory BP measures were significantly lower in the sixth month. FMD was increased significantly and AI, PWV, and UACR were reduced by the treatment. The extent of the changes in PWV and UACR were associated with the changes in all BP measures, but only the change in home morning BP was associated with the change in FMD. The change in AI was not associated with the change in BP levels, but was associated with the change in PWV. A very aggressive antihypertensive therapy guided by home morning BP was effective for surrogate end points in patients with diabetes/prediabetes.

Predictors of proteinuria reduction by monotherapy with an angiotensin receptor blocker, olmesartan

INTRODUCTION

It is known that reduced glomerular filtration rate (GFR) is a crucial factor to limit the blood pressure lowering effect of antihypertensives. In the present study, we tested whether the effects of monotherapy with an angiotensin receptor blocker (ARB) to lower proteinuria could be restricted by reduced GFR.

MATERIALS AND METHODS

Thirty-five renal patients who had albuminuria more than 30 mg/day, but did not have diabetic nephropathy or nephrotic syndrome, were studied before and during eight weeks of monotherapy with ARB, olmesartan.

RESULTS

Blood pressure was lowered from 129 ± 18/79 ± 12 to 116 ± 18/72 ± 12 mmHg (p < 0.0001), while albuminuria was reduced from 614±630 to 343±472 mg/day (p < 0.0001). Albuminuria was inversely correlated with GFR both before and during treatment. Albuminuria reduction was enhanced as plasma renin activity (p = 0.047) and dose of olmesartan were increased (p = 0.04). Although the absolute reduction in proteinuria was not correlated with GFR (p = 0.56), the % reduction was significantly proportional with GFR (p = 0.027). Multiple regression analysis demonstrated that 64% of proteinuria reduction could be explained by baseline levels of albuminuria, GFR and renin activity.

CONCLUSIONS

The reduction in proteinuria by olmesartan may be roughly predicted using baseline GFR and other parameters. These findings clarify that the effect of ARB on proteinuria reduction is restricted by reduced GFR.