High blood pressure is a major factor in progression of diabetic nephropathy

Hypertension increases urinary excretion of immunoglobulin G, ceruloplasmin and transferrin in normoalbuminuric patients with type 2 diabetes mellitus

OBJECTIVE

Increased urinary excretion of certain plasma proteins, such as immunoglobulin G (IgG), ceruloplasmin and transferrin, with different molecular radii of 55 Å or less and different isoelectric points have been reported to precede development of microalbuminuria in patients who have diabetes mellitus with hypertension. We examined how hypertension affects these urinary proteins in a diabetic state.

METHODS

Excretion of IgG, ceruloplasmin, transferrin, albumin, α2-macroglobulin with a large molecular radius of 88 Å and N-acetylglucosaminidase in first-morning urine samples were measured in normoalbuminuric patients (urinary albumin-to-creatinine ratio < 15 mg/g) with hypertension and nondiabetes mellitus (group hypertension, n = 32), type 2 diabetes mellitus and normotension (group diabetes mellitus, n = 52) and type 2 diabetes mellitus and hypertension (group Both, n =45), and in age-matched controls (n = 72).

RESULTS

Urinary IgG, ceruloplasmin, transferrin, albumin and N-acetylglucosaminidase and estimated glomerular filtration rate (eGFR) were significantly elevated in groups diabetes mellitus and Both compared with controls. Furthermore, urinary IgG, ceruloplasmin and transferrin in group Both were significantly higher than those in group diabetes mellitus. These exhibited a positive and relatively strong association with eGFR compared with controls. No significant difference in urinary albumin or N-acetylglucosaminidase was found between the two diabetic groups. In contrast, group hypertension had elevated urinary transferrin without any changes in the other compounds. Urinary α2-macroglobulin did not differ among the four groups.

CONCLUSION

These findings suggest that normoalbuminuric diabetic patients without hypertension have both glomerular hemodynamic changes such as increased intraglomerular hydraulic pressure and altered proximal tubules, and that hypertension increases intraglomerular hydraulic pressure. Increased urinary IgG, ceruloplasmin and transferrin may reflect an increase in intraglomerular hydraulic pressure.

A combined diabetes renal clinic improves risk factor management and progression of renal disease in a district general hospital

AIMS

Aggressive management of vascular risk factors reduces the rate of progression to end-stage renal failure in patients with diabetic nephropathy. The aim of our audit was to clarify whether improvements in patient care could be demonstrated within a short time period after establishing a combined diabetes renal clinic in a district general hospital.

METHODS

A retrospective analysis of weight, glycaemic control, blood pressure control, rate of decline in renal function and appropriate use of medications for vascular risk management for patients in a district general hospital was performed before and after attendance at a combined diabetes renal clinic.

RESULTS

Data were complete for 45 patients. There was no significant change in weight from 14 months before attending the combined clinic, referral to the clinic and after 14 months of mean follow-up. An improvement in mean systolic blood pressure was achieved at the combined diabetes renal clinic (from 147 to 134 mmHg with an average fall of 16.5 mmHg, P < 0.01). The mean glycated haemoglobin (HbA1c) improved from 8.6% to 8% (P = 0.002). The rate of decline in estimated glomerular filtration rate of 1.16 mL min(-1) per month prior to referral improved to 0.21 mL min(-1) per month on attending the combined clinic (P = 0.002).

CONCLUSIONS

Vascular risk factor management was improved and decline in renal function slowed in patients with diabetic nephropathy within a short period of establishing a combined diabetes renal clinic in a district general hospital.

[Blood pressure homeostasis and microvascular complications in diabetic patients]

The retinopathy and nephropathy are among the most prevalent and disabling complications associated to microvascular damage in diabetes mellitus. The severity of hyperglycaemia and the presence of arterial systemic hypertension are among the main risk factors for these complications. The ambulatory blood pressure provided a better understanding of patterns of blood pressure in diabetic patients. There is a growing number of evidence relating diabetic patients with abnormal 24 h blood pressure patterns. Even subtle modifications of these patterns, frequently shown by patients diagnosed as normotensives in office blood pressure measurings, may be implicated in an increased risk of microvascular complications. Hyperglycaemia and these abnormal pressure patterns appear to have a synergistic effect on promoting and aggravating diabetic retinopathy. Impairment of the normal retinal autoregulation is one of the implicated physiopathological mechanisms. Probably, ABP may be useful in predicting an increased risk of microvascular complications on diabetic normotensive patients. The objective of this paper is to provide an updated and clinically oriented review in blood pressure homeostasis and diabetes mellitus.

Development of diabetic nephropathy in the Milan normotensive strain, but not in the Milan hypertensive strain: possible permissive role of hemodynamics

BACKGROUND

Rats of the Milan normotensive strain develop spontaneous glomerulosclerosis, whereas those of the Milan hypertensive strain are resistant to renal disease, possibly due to intrarenal artery hypertrophy protecting from systemic hypertension. To assess the role of hemodynamic versus metabolic factors in diabetic nephropathy, we investigated whether streptozotocin-induced diabetes accelerates glomerulosclerosis in Milan normotensive and/or removes (the hemodynamic) protection in Milan hypertensive rats by reducing preglomerular vascular resistance.

METHODS

Diabetic and nondiabetic Milan normotensive, hypertensive, and progenitor Wistar rats were followed for 6 months for the assessment of renal function and structure.

RESULTS

Proteinuria increased in nondiabetic and diabetic normotensive and, to a lesser extent, in diabetic Wistar, but not hypertensive rats. Serum creatinine increased and creatinine clearance decreased in nondiabetic and diabetic normotensive rats at 6 months. At 1.5 months, diabetic normotensive, but not hypertensive rats showed increased glomerular filtration rate and filtration fraction, suggesting glomerular hypertension. Diabetic nephropathy was detected in diabetic normotensive and Wistar, but not hypertensive rats. Glomerular extracellular matrix and TGF-beta mRNA levels increased with diabetes (and age) in normotensive, but not hypertensive rats. Arterioles and interlobular arteries showed increased media thickness in hypertensive versus normotensive rats, with diabetes reducing it only in the normotensive.

CONCLUSION

These data show that Milan hypertensive rats are not susceptible to diabetic nephropathy, at variance with glomerulosclerosis-prone Milan normotensive rats, thus indicating the importance of genetic background. Our study suggests that the nature of this (genetic) protection might be hemodynamic, with intrarenal artery hypertrophy preventing diabetes-induced loss of autoregulation.

Interactions between hypertension and diabetes on vascular function and structure in rats

Regional 125I-albumin permeation and glomerular structural changes were assessed in male Sprague-Dawley rats with diabetes and/or hypertension. All rats underwent unilateral nephrectomy 2 weeks after induction of diabetes with streptozotocin. At the same time, one-half of the nondiabetic and diabetic animals were placed on 1% saline drinking water and given weekly intramuscular injections of deoxycorticosterone acetate to induce hypertension (systolic blood pressure greater than 150 mm Hg). Vascular permeability studies were performed after 1 and 3 months of hypertension. Hypertension, alone or in combination with diabetes, had no effect on weight gain, plasma glucose, or food consumption, but did increase 24-h urine volume in nondiabetics. In normotensive diabetics and in nondiabetic hypertensive rats, vascular 125I-albumin permeation was increased in eyes, aorta, and new granulation tissue (formed in a subcutaneous fabric implant), and glomerular basement membranes were thickened without any change in the fractional volume of the glomerulus occupied by mesangium. Urinary albumin and IgG excretion in nondiabetic hypertensive rats was increased much more than in normotensive diabetics. Hypertension and diabetes were additive in their effects on 125I-albumin permeation in eyes, aorta, and granulation tissue, and on glomerular basement membrane thickening, but were synergistic in their effects on urinary albumin excretion and mesangial fractional volume. The magnitude of the increase in vascular albumin permeation and urinary albumin and IgG excretion between and 1 and 3 months was much larger in diabetic hypertensive rats than in rats with hypertension or diabetes alone. Neither diabetes nor hypertension, alone or in combination, had any effect on albumin permeation in skeletal muscle, skin, heart, or brain. These findings demonstrate that hypertension and diabetes increase vascular albumin permeation in rats preferentially in tissues that correspond to sites of clinically significant vascular disease in human diabetics. They also attest to an important interaction between blood pressure-induced and diabetes-induced increases in vascular permeability in these tissues and in structural changes in the glomerular vasculature.

Hypertension as a causative diagnosis of patients entering end-stage renal disease programs in the United States from 1980 to 1986

Treatment of hypertension has decreased the incidence of stroke and congestive heart failure consequential to hypertension. To determine whether the incidence of hypertension as a causative diagnosis of end-stage renal disease (ESRD) is also decreasing, we examined the records of the Health Care Financing Administration (HCFA) from 1980 to 1986 regarding the causative diagnoses of patients entering ESRD programs. We found that the incidence of patients entering ESRD programs increased during the study period. Hypertension as a causative diagnosis was a constant proportion of the increase. The greatest increase occurred in patients age 55 or more years. This was strikingly true of black patients. We conclude that there has not been a decrease in the incidence of hypertension as a causative diagnosis for patients entering ESRD programs and that this may be a reflection that treatment of hypertension does not prevent the development of ESRD in some patients. We propose that prospective studies be undertaken to determine whether this is the case.

Relationship between nephropathy, retinopathy, and autonomic neuropathy in patients with type I diabetes

Seventy-two Type I diabetic patients were divided into three groups according to 24 hour urinary albumin excretion (UalbV, mean of three urine collections): normoalbuminuric group 1 (n = 49, UalbV less than or equal to 26 mg/24 h), microalbuminuric group 2 (n = 16, 26 less than UalbV less than or equal to 250 mg/24 h), proteinuric group 3 (n = 7, UalbV greater than 250 mg/24 h). Fluorescein angiography and three cardiovascular autonomic tests were performed. Relative frequencies of ocular findings (no retinopathy/simplex retinopathy/preproliferative and proliferative retinopathy) were determined in each group: group 1 (0.31/0.63/0.06), group 2 (0.56/0.38/0.06), and group 3 (0/0.43/0.57). The most severely affected autonomic function was observed in group 3 (p less than 0.01 vs. group 1). Significant partial correlations were found between UalbV and retinopathy (p less than 0.01), UalbV, and autonomic neuropathy (p less than 0.05), retinopathy and autonomic neuropathy (p less than 0.01), and blood pressure and UalbV and/or autonomic neuropathy (p less than 0.01). No correlation was found between the variables and the previous 15 months' metabolic control. The results suggest that nephropathy, retinopathy, and autonomic neuropathy are signs of a generalized diabetic microangiopathic process whose progression may be influenced by factors other than diabetes duration and metabolic control.