Slowing the progression of renal disease in diabetic patients

Therapeutic approaches to slowing the progression of diabetic nephropathy - is less best?

OBJECTIVE

Angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors are known to reduce proteinuria and have been the first-line agents in the management of diabetic nephropathy for the past 20 years. This review covers recent studies that compare the benefit of additional blockage of the renin-angiotensin-aldosterone system through combination therapy with an ACE inhibitor and ARB, or a direct renin inhibitor (DRI), to monotherapy.

DESIGN

Primary and review articles that addressed the pathophysiology, diagnosis, and therapeutic options for attenuating the progression of diabetic nephropathy were retrieved through a MEDLINE search (January 1990 to December 2012) and the bibliographies of identified articles were reviewed. English language sources were searched using the following search terms: diabetes mellitus, nephropathy, proteinuria, ACE inhibitors, ARBs, and DRIs.

SETTING

Randomized, placebo-controlled, short- and long-term studies published in peer-reviewed journals that were determined to be methodologically sound, with appropriate statistical analysis of the results, were selected for inclusion in this review.

PARTICIPANTS

Adult (≥18 years) patients with diabetic nephropathy.

MEASUREMENTS

Serum creatinine level was used to estimate glomerular filtration rate (GFR). GFR was calculated using the four-variable Modification of Diet in Renal Disease formula. The urine albumin-to-creatinine ratio was measured at baseline and at the conclusion of each study. A value between 3.4 mg/mmol and below 33.9 mg/mmol was defined as microalbuminuria. A value of 33.9 mg/mmol or more (approximately 300 mg/g creatinine) was defined as macroalbuminuria.

RESULTS

ACE inhibitors and ARBs are now the mainstay of treatment for diabetic nephropathy. However, combination therapy with an ACE inhibitor and an ARB, or DRI, has not been found to be more effective than monotherapy with an ACE inhibitor or ARB, and may increase the risk of hyperkalemia or acute kidney injury.

CONCLUSION

Both ACE inhibitors and ARBs remain the first-line agents in attenuating the progression of diabetic nephropathy; however, recent studies suggest that combining an ACE inhibitor with an ARB, or combining a DRI with an ACE inhibitor or ARB, may increase adverse events without clinical benefits to offset them.

Prognostic influence of metformin as first-line chemotherapy for advanced nonsmall cell lung cancer in patients with type 2 diabetes

BACKGROUND

It has been reported that antidiabetic drugs affect the risk of cancer and the prognosis of patients with diabetes, but few studies have demonstrated the influence of different antidiabetic agents on outcomes after anticancer therapy among patients with cancer. The objective of this study was to evaluate the influence of the antidiabetic drugs metformin and insulin on the prognosis of patients with advanced nonsmall cell lung cancer (NSCLC) plus type 2 diabetes who received first-line chemotherapy.

METHODS

Data on patients with NSCLC who had diabetes from 5 hospitals in China during January 2004 to March 2009 were reviewed retrospectively. Ninety-nine patients were included in the final analysis. The influence of metformin and insulin on chemotherapy response rates and survival in these patients was evaluated.

RESULTS

Chemotherapy with metformin (Group A) produced superior results compared with insulin (Group B) and compared with drugs other than metformin and insulin (Group C) in terms of both progression-free survival (PFS) (8.4 months vs 4.7 months vs 6.4 months, respectively; P = .002) and overall survival (OS) (20.0 months vs 13.1 months vs 13.0 months, respectively; P = .007). Although no significant differences in the response rate (RR) were observed between these 3 groups, when groups B and C (ie, the nonmetformin group) were combined, there was a tendency for better disease control in Group A than that in nonmetformin group. No significant difference in survival was observed between chemotherapy with insulin (Group B) versus other drugs (Group C).

CONCLUSIONS

The current data suggested that metformin may improve chemotherapy outcomes and survival for patients who have NSCLC with diabetes.

Efficacy of Combination Therapy for Systolic Blood Pressure in Patients With Severe Systolic Hypertension: The Systolic Evaluation of Lotrel Efficacy and Comparative Therapies (SELECT) Study

Systolic hypertension is predominant among patients over 50 years of age, is a more important cardiovascular risk factor than diastolic blood pressure, and is more difficult to control than diastolic blood pressure. Consequently, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommends combination therapy as first-line treatment for patients with stage 2 hypertension. In the Systolic Evaluation of Lotrel Efficacy and Comparative Therapies (SELECT) study, 24-hour ambulatory blood pressure monitoring was used to identify patients with systolic hypertension and to determine the impact of 8 weeks of treatment with either amlodipine besylate/benazepril HCl 5/20 mg combination therapy (n=149), amlodipine besylate 5 mg (n=146), or benazepril HCl 20 mg (n=148). Combination therapy was significantly more effective in reducing systolic blood pressure and pulse pressure than either monotherapy (p<0.0001). Significantly greater percentages of patients in the combination group compared with either monotherapy achieved blood pressure control (p<0.0001). Adverse events were low in all three treatment arms, with less peripheral edema in the combination group than in the amlodipine-treated group. The combination of amlodipine besylate/benazepril HCl given to patients with stage 2 systolic hypertension resulted in significantly greater reductions in blood pressure and pulse pressure than those seen with monotherapy and was at least as well tolerated as the separate components. This data supports the recommendation of the JNC 7 for the use of combination therapy in patients with stage 2 hypertension.

The effects of captopril and losartan on erythrocyte membrane Na+/K(+)-ATPase activity in experimental diabetes mellitus

Diabetes mellitus induces a decrease in sodium potassium-adenosine triphosphatase (Na+/K(+)-ATPase) activity in several tissues in the rat and red blood cells (RBC) and nervous tissue in human patients. This decrease in Na+/K(+)-ATPase activity is thought to play a role in the development of long-term complications of the disease. Angiotensin enzyme inhibitors (ACEi) and angiotensin-II receptor antagonists (ARBs) reduce proteinuria and retard the progression of renal failure in patients with IDDM and diabetic rats. We investigated the effects of captopril and losartan, which are used in the treatment of diabetic nephropathy, on Na+/K(+)-ATPase activity. Captopril had an inhibitory effect on red cell plasma membrane Na+/K+ ATPase activity, but losartan did not. Our study draws attention to the inhibitory effect of captopril on Na+/K+ ATPase activity. Micro and macro vascular complications are preceeding mortality and morbidity causes in diabetes mellitus. There is a strong relationship between the decrease in Na+/K+ ATPase activity and hypertension. The non-sulphydryl containing ACEi and ARBs must be the choice of treatment in hypertensive diabetic patients and diabetic nephropathy.

The Renal Protective Effects of Angiotensin II Receptor Blockers in Type 2 Diabetes Mellitus

OBJECTIVE

To review the renal protective effects of angiotensin II receptor blockers (ARBs) in patients with type 2 diabetes mellitus.

DATA SOURCES

A MEDLINE search (1966-March 2004) was completed using irbesartan, candesartan, losartan, valsartan, eprosartan, olmesartan, telmisartan, renal protection, nephropathy, albuminuria, and type 2 diabetes mellitus as key words.

STUDY SELECTION AND DATA EXTRACTION

All identified English-language articles were reviewed. References of the identified sources were used to identify additional articles. Articles representative of the subject matter of our review were included.

DATA SYNTHESIS

ARBs have extensive data showing their renal protective benefits in hypertensive type 2 diabetic patients with microalbuminuria or proteinuria. The benefits are over and above that of blood pressure reduction alone and extend to normotensive diabetic patients as well. Maximizing the ARB dose before adding additional therapies or another renal-protecting agent (angiotensin-converting enzyme [ACE] inhibitor or non-dihydropyridine calcium-channel blocker) may be superior to adding another class of antihypertensive, even if similar blood pressures can be achieved.

CONCLUSIONS

ARBs are an important therapy for hypertensive type 2 diabetic patients and can benefit normotensive diabetic patients as well. ARB dosage optimization or the addition of a second renoprotective agent (ACE inhibitor or non-dihydropyridine calcium-channel blocker) may be important for optimal renoprotection, although further research is clearly needed in this area.

Calcium channel blockers and the kidney

Although end-stage renal disease (ESRD) currently affects only a small percentage (<0.2%) of the US population, its precursor, the mild and moderate forms of chronic kidney disease (CKD), affects 11% of the population, with significant growth in both ESRD and CKD anticipated in the rapidly aging US population. The primary diagnoses in the majority of ESRD patients are diabetes and hypertension. Results of clinical studies demonstrate that the level of proteinuria and sympathetic activation contribute to the progression of CKD to ESRD. There are sufficient clinical data to demonstrate that the dihydropyridine calcium channel blocker (DHP CCB) class of antihypertensives such as amlodipine and nifedipine, although effective in reducing systemic hypertension, lack activity in reducing proteinuria or attenuating sympathetic activity. Experimental studies and a limited number of clinical studies suggest that non-DHP CCBs, including verapamil and diltiazem, have a mechanism of action that differs from DHP CCBs. Non-DHP CCBs could potentially attenuate sympathetic activity and reduce protein excretion in patients with CKD.