Impact of metabolic control in progression of clinical diabetic nephropathy

Poor Glycemic Control Is Associated With More Rapid Kidney Function Decline After the Onset of Diabetic Kidney Disease

BACKGROUND

The role of glycemic control and its variability on the rate of kidney function decline after the onset of diabetic kidney disease (DKD) remains unclear.

METHODS

The association between baseline glycated hemoglobin (HbA1c) and rates of estimated glomerular filtration rate (eGFR) loss during follow-up was examined by mixed-effects linear regression in 530 individuals with type 1 diabetes and early-to-moderate DKD from the Preventing Early Renal Loss (PERL) trial and 2378 individuals with type 2 diabetes and established DKD from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. The benefit of intensive vs standard glycemic control in slowing eGFR decline was examined in ACCORD. The associations between continuous glucose monitoring-derived short-term glycemic variability indices and rate of eGFR decline were also evaluated in PERL.

RESULTS

A higher baseline HbA1c was associated with a more negative eGFR slope in both PERL and ACCORD (-0.87 and -0.27 mL/min/1.73 m2/year per Hba1c unit increment, P < .0001 and P = .0002, respectively). In both studies, the strength of this association progressively increased with increasing levels of albuminuria (P for interaction <.05). Consistent with this, the benefit of intensive glycemic control on eGFR decline was greater in ACCORD participants with severe rather than moderate albuminuria (+1.13 vs + 0.26 mL/min/1.73 m2/year, P = .01). No independent associations were found in PERL between short-term glycemic variability indices and rate of eGFR decline.

CONCLUSION

In both type 1 and type 2 diabetes, poor glycemic control is associated with a more rapid rate of glomerular filtration rate decline after DKD onset, especially in persons with severe albuminuria.

Prevalence of microalbuminuria and its correlates among diabetic patients attending diabetic clinic at National Guard Hospital in Alhasa

INTRODUCTION

Diabetes mellitus is one of the most common diseases encountered in clinical practice. Diabetic nephropathy is a common consequence of long-standing diabetes mellitus; microalbuminuria (MA) is considered an early stage of diabetic nephropathy.

OBJECTIVES

To determine the prevalence of miciroalbuminuria in diabetic patients and factors associated with MA.

MATERIALS AND METHODS

This cross-sectional study was conducted in the diabetic clinic of the primary health center of the National Guard Hospital. Diabetes type 2 patients between the ages of 20-60 years who attended the clinic in 2012 were included in this study. Data were collected by reviewing medical records for demographic and disease-related variables. MA was detected by measuring the albumin to creatinine ratio, and MA was diagnosed if this ratio was between 30 and 300 mg/g on two occasions.

RESULTS

MA was found in 37.4% of the sample and the rate was significantly higher among females (P < 0.027). MA was positively related to body mass index (BMI) (P < 0.002), the presence of hypertension (P < 0.000), duration of diabetes (P < 0.000), glycated hemoglobin (P < 0.000), fasting plasma glucose (P < 0.000), and low-density lipoprotein (LDL) (P < 0.043). No statistically significant correlation was found between MA and age, creatinine level, high-density lipoprotein, and triglyceride.

CONCLUSION

The prevalence of MA in patients with diabetes in this study was high. The study suggests the need to screen for MA early, and the active management of modifiable risk factors, in particular, hyperglycemia, hypertension, LDL, and BMI, to reduce the burden of future end-stage renal disease.

Adjusting the 17β-Estradiol-to-Androgen Ratio Ameliorates Diabetic Nephropathy

Diabetes is manifested predominantly in males in experimental models, and compelling evidence suggests that 17β-estradiol (E2) supplementation improves hyperglycemia in humans. We previously generated a severely diabetic transgenic (Tg) mouse model by β-cell–specific overexpression of inducible cAMP early repressor (ICER) and found that male but not female ICER-Tg mice exhibit sustained hyperglycemia and develop major clinical and pathologic features of human diabetic nephropathy (DN). Thus, we hypothesized that differences in circulating hormone levels have a key role in determining susceptibility to diabetes. Here, we examined whether DN in male ICER-Tg mice is rescued by adjusting the androgen-to-E2 ratio to approximate that in normoglycemic female ICER-Tg mice. We treated hyperglycemic male ICER-Tg mice with orchiectomy (ORX), E2 pellet implantation, or both. E2 pellet implantation at an early stage of DN with or without ORX caused a rapid drop in blood glucose and a dramatic increase in β-cell number, and it markedly inhibited DN progression [namely, E2 reduced glomerulosclerosis, collagen 4 deposition and albuminuria, and prevented hyperfiltration]. Furthermore, E2 pellet implantation was more effective than ORX alone and induced a remarkable improvement, even when initiated at advanced-stage DN. In contrast, induction of normoglycemia by islet transplant in ICER-Tg mice eliminated albuminuria but was less effective than E2 + ORX in reducing glomerulosclerosis, collagen 4 deposition, and hyperfiltration. These findings indicate that E2 treatment is effective, even after establishment of DN, whereas glucose normalization alone does not improve sclerotic lesions. We propose that E2 intervention is a potential therapeutic option for DN.

Diabetic kidney disease: a clinical update from Kidney Disease: Improving Global Outcomes

The incidence and prevalence of diabetes mellitus (DM) continue to grow markedly throughout the world, due primarily to the increase in type 2 DM (T2DM). Although improvements in DM and hypertension management have reduced the proportion of diabetic individuals who develop chronic kidney disease (CKD) and progress to end-stage renal disease (ESRD), the sheer increase in people developing DM will have a major impact on dialysis and transplant needs. This KDIGO conference addressed a number of controversial areas in the management of DM patients with CKD, including aspects of screening for CKD with measurements of albuminuria and estimated glomerular filtration rate (eGFR); defining treatment outcomes; glycemic management in both those developing CKD and those with ESRD; hypertension goals and management, including blockers of the renin-angiotensin-aldosterone system; and lipid management.

Cost-effective strategies in the prevention of diabetic nephropathy

A significant subgroup of patients with diabetes mellitus are predisposed to developing diabetic nephropathy and it is in this subgroup that other diabetes- related complications, and in particular greatly increased cardiovascular disease risk, are concentrated. The high personal, social and financial costs of managing end-stage renal failure and the other complications associated with diabetic nephropathy make a powerful case for screening and effective intervention programmes to prevent the condition or retard its progression. As major breakthroughs in finding genetic susceptibility factors remain elusive, screening efforts continue to be based on microalbuminuria testing, despite increasing recognition of its limitations as a positive predictor of nephropathy. Interventions have been extensively studied, but results remain conflicting. Economic evaluations of such screening and intervention programmes are essential for health planners, yet models of the cost/benefit ratio of such interventions often rely on a rather slim evidence base. Where economic models are developed, they are frequently based on those papers that propound the greatest clinical benefits of a given intervention, leading to a possible over-estimation of the advantages of the chosen approach. Furthermore, the benefits of even such generally accepted interventions as ACE inhibitor treatment are less firmly established than generally appreciated. Lifestyle interventions are instinctively attractive, but are by no means a low-cost option (as is often assumed by both medical professionals and politicians). This review critically assesses the evidence for clinical efficacy and economic benefit of microalbuminuria screening and interventions such as intensive glycaemic control, antihypertensive treatment, ACE inhibition and angiotensin receptor blockade, dietary protein restriction and lipid-modifying therapy. The various costs associated with diabetic nephropathy are so great that even expensive interventions may have a favourable cost/benefit ratio, provided they are truly effective.

Remission of nephrotic-range albuminuria in type 1 diabetic patients

OBJECTIVE

To evaluate the cumulative incidence of nephrotic-range albuminuria (NRA), the frequency of remission, and the impact on progression, we analyzed data from a prospective cohort study of type 1 diabetic patients with diabetic nephropathy.

RESEARCH DESIGN AND METHODS

All of the albuminuric type 1 diabetic patients (n = 321, 121 women), who had at least yearly measurements of glomerular filtration rate (GFR) with a (51)Cr-EDTA plasma clearance technique and were followed for at least 3 years, were evaluated. NRA, defined as persistent albuminuria >2,500 mg/24 h, occurred in 126 patients (35 women) aged (mean +/- SD) 34 +/- 8 years, with duration of diabetes 22 +/- 8 years and follow-up time from onset of NRA (median [range]) 8.7 (3.0-20.9) years. Remission of NRA was defined as sustained albuminuria <600 mg/24 h for at least 1 year.

RESULTS

The cumulative incidence of NRA was 39%. Remission was induced in 28 of 126 (22%) patients; 21 were predominantly treated with ACE inhibitors, 7 with non-ACE inhibitor medications. Remission lasted 3.6 (1.0-18.1) years. More women (37%) than men (16%) obtained remission (P = 0.01). In the remission group compared with the no-remission group, mean arterial blood pressure (mean +/- SEM) was reduced (102 +/- 1 vs. 106 +/- 1 mmHg, P < 0.01), the rate of decline in GFR was diminished (3.8 +/- 0.6 vs. 7.5 +/- 0.5 ml x min(-1) x year(-1), P < 0.001), and serum cholesterol was lower (5.3 +/- 0.2 vs. 6.1 +/- 0.1 mmol/l, P < 0.01) during the whole follow-up period. No difference in glycemic control was found between groups (HbA(1c) 9.2 vs. 9.4%, NS).

CONCLUSIONS

In contrast to observations made before the use of antihypertensive treatment, our prospective observational study suggests that aggressive antihypertensive treatment with and without ACE inhibitors can induce long-lasting remission in a sizeable fraction of type 1 diabetic patients with NRA. The group of patients obtaining remission is characterized by slow progression of diabetic nephropathy and improved cardiovascular risk profile.

Effect Of Intensive Insulin Therapy On Progression Of Overt Nephropathy In Patients With Type 1 Diabetes Mellitus

OBJECTIVE

To assess the effects of chronic (long-term) intermittent intravenous insulin therapy (CIIIT) on the progression of overt nephropathy in patients with type 1 diabetes mellitus.

METHODS

We undertook a retrospective longitudinal three-center study of 31 patients with type 1 diabetes mellitus and overt nephropathy, who were receiving intensive subcutaneous insulin therapy (four insulin injections daily) and weekly CIIIT. All study patients had follow-up consultations weekly for at least 12 months (mean duration, 37.0 +/- 4.6 months). Each patient had monthly hemoglobin A(1c) (by high-performance liquid chromatography) and semiannual creatinine clearance determinations.

RESULTS

The hemoglobin A(1c) levels declined significantly from 8.6 +/- 0.6% to 7.6 +/- 0.3% (P = 0.0062) during the study period. The creatinine clearance remained essentially unchanged (from 46.1 +/- 3.0 mL/min per 1.73 m 2 at baseline to 46.0 +/- 3.9 mL/min per 1.73 m 2 at the end of the observation period, with an average annualized slope increase of 3.39 +/- 1.5 mL/min per year--no significant difference).

CONCLUSION

The addition of CIIIT to intensive subcutaneous insulin therapy in patients with type 1 diabetes mellitus seems to arrest or appreciably reduce the progression of overt diabetic nephropathy, as well as substantially improve their glycemic control.

Nephropathy and hypertension in diabetes

The treatment of the patient with diabetes, with or without hypertension, is complex and challenging. Hyperglycemic treatment should ideally not only control blood glucose, but also prevent the chronic complications and associated metabolic derangements that can lead to increased morbidity and mortality. Hypertensive treatment should not only decrease blood pressure, but also reduce the risk of macrovascular and microvascular disease. The use of antihypertensive agents that improve insulin resistance, dyslipidemia, glycemic control, and nephropathy is preferred whenever possible. The real key to success in the care of the hypertensive diabetic patient is adequate screening and appropriate, early treatment. Currently, there is ample evidence to support the use of intensive management with the goal of near-normalization of blood glucose levels in most patients with diabetes. Similarly, aggressive treatment of hypertension is the current standard. Accomplishing these goals helps to prevent the development of chronic diabetic complications, including nephropathy. ESRD need not be the inevitable outcome for individuals with early diabetic nephropathy. Interventions currently available that are targeted at the known modifiable risk factors underlying the development and progression of diabetic nephropathy offer the best hope for reducing the incidence and severity of this complication. Prevention of the complications of diabetes, including nephropathy, must be the goal for the future on behalf of all those who now have diabetes.

Role of Glycemic Control and Protein Restriction in Clinical Management of Diabetic Kidney Disease

OBJECTIVE

To assess the role of control of blood glucose levels and restriction of dietary protein in the management of diabetic nephropathy.

METHODS

We summarize the results of pertinent published studies of glycemic control and modification of protein intake to provide information about strategies that potentially could benefit patients with diabetes and renal dysfunction.

RESULTS

Considerable evidence is available to support the contention that improved glycemic control may have beneficial effects on the development and progression of diabetic renal disease. Maximal benefits of improved glycemia occur when instituted before the onset of macroalbuminuria. Once overt diabetic nephropathy is established, improved glycemic control may not be beneficial. Current evidence indicates that a glycosylated hemoglobin level of less than 8.1% should be the glycemic goal. At this level, the risk of developing micro-albuminuria is substantially reduced, and the risk of hypoglycemia is minimized. Most studies have been conducted in type I diabetes, and the results have been extrapolated to type II diabetes. Whether improved glycemic control will be equally beneficial in the nephropathy of type II diabetes has yet to be determined. Although some scientific evidence supports dietary protein restriction in patients with diabetic nephropathy, the extent of restriction needed for optimal benefits and minimal side effects remains to be determined. On the basis of current information, patients with both types of diabetes who have evidence of nephropathy should have protein limited to the recommended dietary allowance for adults (0.8 g/kg of body weight per day or approximately 10% of total daily caloric intake), and protein should be derived primarily from vegetable and lean animal sources.

CONCLUSION

End-stage renal disease is not inevitable in patients with diabetic nephropathy. Normalization of glucose levels and modification of protein intake can favorably influence the course of diabetes-related kidney disease.

The quantitative relationship between treated blood pressure and progression of diabetic renal disease

Antihypertensive therapy reduces the rate at which glomerular filtration rate (GFR) declines (delta GFR) in diabetic nephropathy; however, the optimal blood pressure is unknown. The quantitative relationship between treated blood pressure and delta GFR was analyzed retrospectively in 59 patients with established diabetic nephropathy and treated hypertension using weighted univariate and weighted multivariate regression. The GFR was calculated using the Cockcroft and Gault formula. More rapid GFR loss correlated most strongly with higher diastolic blood pressures (r = 0.70; P < 0.0001); for each millimeter of mercury of diastolic blood pressure, the GFR decreased by 0.69 mL/min/yr. This relationship remained present if those individuals with diastolic pressures greater than 90 mm Hg were eliminated from the study (r = 0.50; P < 0.001). The correlation for systolic blood pressure was weaker (r = 0.30; P < 0.05) and explained completely by covariance between systolic and diastolic blood pressures. The correlation for mean blood pressure (r = 0.59; P < 0.0001) fell between the correlations for diastolic and systolic blood pressures. Proteinuria, serum albumin concentration, and serum cholesterol concentration also correlated with delta GFR. In multivariate analysis, neither these indices of disease severity nor the initial GFR explained the correlation between delta GFR and diastolic blood pressure. Age, sex, race, type of diabetes, and percentage of glycosylated hemoglobin did not correlate with delta GFR.

Diabetic nephropathy in insulin-dependent patients

Diabetic nephropathy is a serious complication of insulin-dependent diabetes mellitus (IDDM) that affects 30% to 40% of IDDM patients with a predictable time of onset. Epidemiologic data suggest that either a genetic susceptibility, perhaps for hypertension (HTN), or an environmental exposure selects out that subset of IDDM patients and destines them to develop diabetic nephropathy. Hopefully, assessing glomerular hyperfiltration, urinary albumin excretion rate (AER), glycemic control, mean arterial pressure (MAP), and perhaps early morphologic changes will allow early identification of this high-risk group of IDDM patients before overt nephropathy is present. Once nephropathy appears, renal function inexorably declines, although the natural history of this progression may be changing with earlier therapeutic intervention. IDDM patients with nephropathy suffer a high mortality rate compared with IDDM patients without nephropathy or with nondiabetic end-stage renal disease patients. This is primarily due to malignant atherosclerotic disease manifested as coronary, peripheral, and cerebral arterial disease. Therapeutic interventions of demonstrated benefit in slowing the rate of decline of glomerular filtration rate (GFR) include blood pressure control and low-protein diets. Strict blood sugar control or treatment with aldose reductase inhibitors, converting enzyme inhibitors (CEIs), or inhibitors of advanced glycosylation end-product formation are of possible benefit, but are awaiting clinical trial results.

Improved survival in patients with diabetic nephropathy

The effect of early antihypertensive treatment on survival of patients with diabetic nephropathy was evaluated by studying two cohorts of Type 1 (insulin-dependent) diabetic patients developing persistent proteinuria in I: 1957-1973 (late treatment group n = 49) and II: 1979-1983 (early treatment group n = 71). At onset of nephropathy, the two cohorts were comparable with regard to age (29(8) vs 30(8) years, mean (SD], duration of diabetes (16(6) vs 18(7) years), blood pressure (132(16)/85(11) vs 134(16)/86(8) mm Hg), proteinuria (0.8(0.5-1.2) vs 0.8(0.6-1.2) g x 24 h-1, median (quartiles] and serum creatinine (87(14) vs (85(16) mumol x 1(-1]. The patients were followed frequently at the outpatients' clinic until death or for a median duration of 8 years. In the first cohort antihypertensive treatment was seldom used, whereas, in the second cohort antihypertensive treatment was started when blood pressure reached 144(18)/93(7) mm Hg. The probability of survival with a functioning kidney for more than 8 years was 48% in the first cohort and 87% in the second cohort, p less than 0.001. The improvement of survival was due mainly to a decreased mortality from uraemia. Early antihypertensive treatment is the most likely explanation for this improvement.

Prognosis in diabetic nephropathy

OBJECTIVE

To assess the effect of long term antihypertensive treatment on prognosis in diabetic nephropathy.

DESIGN

Prospective study of all insulin dependent diabetic patients aged under 50 with onset of diabetes before the age of 31 who developed diabetic nephropathy between 1974 and 1978 at Steno Memorial Hospital.

SETTING

Outpatient diabetic clinic in tertiary referral centre.

PATIENTS

Forty five patients (20 women) with a mean age of 30 (SD 7) years and a mean duration of diabetes of 18 (7) years at onset of persistent proteinuria were followed until death or for at least 10 years.

INTERVENTIONS

Antihypertensive treatment was started a median of three (0-13) years after onset of nephropathy. Four patients (9%) received no treatment, and 9 (20%), 13 (29%), and 19 (42%) were treated with one, two, or three drugs, respectively. The median follow up was 12 (4-15) years.

MAIN OUTCOME MEASURES

Arterial blood pressure and death.

RESULTS

Mean blood pressure at start of antihypertensive treatment was 148/95 (15/50) mm Hg. Systolic blood pressure remained almost unchanged (slope -0.01 (95% confidence interval -0.39 to 0.37) mm Hg a year) while diastolic blood pressure decreased significantly (0.87 (0.65 to 1.10) mm Hg a year) during antihypertensive treatment. The cumulative death rate was 18% (8 to 32%) 10 years after onset of nephropathy, in contrast to previous reports of 50% to 77% 10 years after onset of nephropathy. As in previous studies, uraemia was the main cause of death (9 patients; 64%).

CONCLUSIONS

The prognosis of diabetic nephropathy has improved during the past decade largely because of effective antihypertensive treatment.