Does ACE inhibition slow progression of glomerulopathy in patients with Type 2 diabetes mellitus?

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Effect of losartan on prevention and progression of early diabetic nephropathy in American Indians with type 2 diabetes

Angiotensin receptor blockers are renoprotective in hypertensive azotemic patients with type 2 diabetes, but their efficacy in early diabetic kidney disease is uncertain. We performed a 6-year randomized clinical trial in 169 American Indians with type 2 diabetes and normoalbuminuria (albumin/creatinine ratio [ACR] <30 mg/g; n = 91) or microalbuminuria (ACR 30-299 mg/g; n = 78) at baseline. The primary outcome was decline in glomerular filtration rate (GFR) to ≤60 mL/min or to half the baseline value in subjects who entered with GFR <120 mL/min. Another outcome was differences in glomerular structure at end of treatment. Subjects received 100 mg losartan or placebo daily. GFR was measured annually; 111 subjects underwent kidney biopsies. Only nine subjects reached the GFR outcome, and the unadjusted hazard ratio (losartan vs. placebo) was 0.50 (95% CI, 0.12-1.99). Differences in mesangial fractional volume were not estimated in the combined albuminuria groups because of an interaction with treatment assignment. In separate analyses, mesangial fractional volume was lower in subjects treated with losartan in the microalbuminuria group (18.8 vs. 25.6%; P = 0.02), but not in the normoalbuminuria group (19.6 vs. 17.8%; P = 0.86). Treatment with losartan may preserve some features of kidney structure in American Indians with type 2 diabetes and microalbuminuria.

When to initiate ACEI/ARB therapy in patients with type 1 and 2 diabetes

Angiotensin converting enzyme inhibitors (ACEI) and angiotensin 2 receptor blockers (ARB) have become a mainstay of adjunctive therapy for the prevention and amelioration of diabetic nephropathy. Although ACEI were shown over 20 years ago to slow the rate of loss of renal function in diabetic subjects with decreased renal function, the question of how early in the course of diabetes to introduce them remains unresolved. Recent studies suggest that very early initiation of ACEI/ARB therapy may not have demonstrable beneficial effects even over a period of years.

The role of renin angiotensin system inhibition in kidney repair

Chronic kidney diseases share common pathogenic mechanisms that, independently from the initial injury, lead to glomerular hyperfiltration, proteinuria, and progressive renal scarring and function loss. Inhibition of the renin angiotensin system (RAS) has been consistently found to reduce or halt the progressive deterioration of renal function through reduction of blood pressure and proteinuria, the two main determinants of renal function decline. In few instances, RAS inhibition may even promote amelioration of the glomerular filtration rate. Animal data suggest that chronic therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor type I blockers promotes regression of glomerulosclerosis, even in later phases of the disease. In humans, studies investigating the effect of angiotensin II inhibition on renal structural changes have shown inconsistent results, possibly due to small numbers and/or short duration of follow-up. Whether regression of glomerulosclerosis relies on a direct regenerative effect of RAS inhibition or on spontaneous kidney self-repair after the injury has been removed is still unknown. Improved understanding of mechanisms that promote renal regeneration may help in designing specific therapies to prevent the development of end-stage renal disease. This is a desirable goal, considering the economic burden of chronic kidney diseases and their effect on morbidity and mortality.

Prevalence of atubular glomeruli in type 2 diabetic patients with nephropathy

BACKGROUND

Atubular glomeruli have been identified in a number of chronic renal diseases and have been linked to declining renal function. In type 1 diabetes they are present predominantly in proteinuric patients. We investigated the prevalence of atubular glomeruli in type 2 diabetes and their relationship to renal function.

METHODS

Renal biopsies from 12 type 2 diabetic patients with nephropathy were processed for light and electron microscopy and analysed using standard stereological techniques. Abnormalities at the glomerular tubular junction were quantified using an index of junctional atrophy (IJA).

RESULTS

There was no relationship between the degree of proteinuria and the presence of atubular glomeruli or atrophic tubules. Creatinine clearance correlated with the IJA (r = -0.70, P = 0.011), percent sclerosed glomeruli (r = -0.59, P = 0.027) and interstitial volume fraction (r = -0.54, P = 0.037). The IJA also correlated with foot process width and volume fraction interstitium (r = 0.58, P = 0.049 for both). Percent sclerosed glomeruli correlated with mesangial (r = 0.65, P = 0.012) and interstitial (r = 0.69, P = 0.007) volume fractions.

CONCLUSIONS

In contrast to type 1 diabetes, atubular glomeruli and atrophic tubules occur in type 2 diabetic patients with low levels of proteinuria; their development may influence the progressive change in GFR. Both glomerular and interstitial damage may lead to the development of atubular glomeruli in type 2 diabetic nephropathy.

Effects of perindopril in hypertensive patients with or without type 2 diabetes mellitus, and with altered insulin sensitivity

Impaired insulin sensitivity and hypertension are risk factors for atherosclerosis, which in turn leads to a variety of cardiovascular diseases. In both conditions, the risks of morbidity and mortality appear to be further increased. Impaired insulin sensitivity is also a precursor for diabetes. The renin-angiotensin-aldosterone system (RAAS) is implicated in the development of both hypertension and insulin resistance. Antihypertensive agents that act by blocking the RAAS, such as angiotensin-converting enzyme (ACE) inhibitors, may improve insulin sensitivity and therefore prevent the deleterious consequences of insulin resistance, including type 2 diabetes. ACE inhibitors appear to improve insulin sensitivity in patients with hypertension and insulin resistance, including diabetes. This review assesses the literature surrounding the use of the ACE inhibitor perindopril in patients with hypertension and varying degrees of insulin resistance, including the effects of perindopril in preventing the development of diabetes and subsequent cardiovascular morbidity and mortality.

Are glomerular volume differences between type 1 and type 2 diabetic patients pathologically significant?

The observation that patients with type 2 diabetes tend to have larger glomeruli than patients with type 1 diabetes was first made more than 10 years ago. It has also been noted that type 2 diabetic patients with nephropathy often have more heterogeneous renal function and structure than type 1 patients. However, whether these observations are linked or have any bearing on the progression of nephropathy in the two types of diabetes remains uncertain. Here we put forward several hypotheses as to why glomerular volume in type 1 differs from that in type 2 diabetes. We suggest that although type 1 and type 2 diabetic patients appear to progress through similar stages of diabetic nephropathy, the route they take may differ. Differences in the way in which the glomeruli respond to the diabetic milieu may enable some type 2 diabetic patients to preserve their filtration surface in the face of an expanding mesangium.

Reversibility of established diabetic glomerulopathy by anti-TGF-beta antibodies in db/db mice

Treatment with a neutralizing anti-transforming growth factor-beta (TGF-beta) antibody can prevent the development of diabetic nephropathy in the db/db mouse, a model of type 2 diabetes. However, it is unknown whether anti-TGF-beta therapy can reverse the histological lesions of diabetic glomerulopathy once they are established. Diabetic db/db mice and their non-diabetic db/m littermates were allowed to grow until 16 weeks of age, by which time the db/db mice had developed glomerular basement membrane (GBM) thickening and mesangial matrix expansion. The mice were then treated with an irrelevant control IgG or a panselective, neutralizing anti-TGF-beta antibody for eight more weeks. Compared with control db/m mice, the db/db mice treated with IgG had developed increased GBM width (16.64+/-0.80 nm vs. 21.55+/-0.78 nm, P<0.05) and increased mesangial matrix fraction (4.01+/-0.81% of total glomerular area vs. 9.55+/-1.04%, P<0.05). However, the db/db mice treated with anti-TGF-beta antibody showed amelioration of GBM thickening (18.40+/-0.72 nm, P<0.05 vs. db/db-IgG) and mesangial matrix accumulation (6.32+/-1.79%, P<0.05 vs. db/db-IgG). Our results demonstrate that inhibiting renal TGF-beta activity can partially reverse the GBM thickening and mesangial matrix expansion in this mouse model of type 2 diabetes. Anti-TGF-beta regimens would be useful in the treatment of diabetic nephropathy.

Blood pressure control--effects on diabetic nephropathy progression: how low does blood pressure have to be?

Hypertension and diabetes are independent risk factors for both cardiovascular disease and renal complications. Coexistence of these comorbid conditions predisposes the patient to a much greater risk of progression to end-stage renal disease. Combined with the increased cardiovascular mortality, this has led to recent Joint National Committee-VI recommendations for the initiation of antihypertensive therapy for people with diabetes at a blood pressure of 130/85 mm Hg, a level lower than that recommended for the nondiabetic population. Results of a review of recently published investigations on the effects of blood pressure on diabetic nephropathy progression are presented in this article. This review finds evidence to support reducing the mean arterial blood pressure to levels below 95 mm Hg, a level that is even lower than the blood pressure of 130/80 mm Hg (mean arterial pressure of 97 mm Hg) recommended by the American Diabetes Association and National Kidney Foundation. The effect of blood pressure on renal disease progression is linear and appears to have no lower threshold for the benefits of blood pressure reduction on limiting nephropathy progression. The answer to the question of how low does blood pressure have to be to minimize the effects of blood pressure on diabetic nephropathy progression might be "the lower, the better."