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Query: UMLS:C0011854 (type 1 diabetes)
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It is a widely held view that when a patient with type I diabetes mellitus and diabetic retinopathy or neuropathy develops renal impairment the renal lesion will be diabetic glomerulonephropathy. This has been extrapolated to apply to type II diabetes. We have performed a retrospective study of the clinical data of patients with diabetes mellitus who have had a renal biopsy between November 1980 and December 1990. Seventy-one patients were biopsied, data were available on 68. Nineteen of 22 type I diabetics had diabetic glomerulopathy, two had diabetic glomerulopathy in addition to another lesion only one patient did not have diabetic glomerulopathy. Twenty-three of 46 type II diabetics had diabetic glomerulopathy alone 22 having an alternative diagnosis. Eight further patients were identified who were not known to be diabetic at the time of renal biopsy, but whose biopsies revealed diabetic glomerulopathy. These data suggest that patients with type II diabetes and renal impairment should have a renal biopsy as part of their investigation.
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PMID:Increased prevalence of renal biopsy findings other than diabetic glomerulopathy in type II diabetes mellitus. 133 73

Diabetic nephropathy, clinically defined by overt albuminuria, hypertension and declining GFR, affects 25-35% of IDDM patients. The risk of nephropathy peaks during the second decade of IDDM and declines thereafter, suggesting that only a subset of IDDM patients is at risk for nephropathy. A role for hypertension in the progression of established renal damage in IDDM is now accepted; however the role of hypertension in the genesis of diabetic nephropathy is not yet clear. Mesangial expansion is a characteristic lesion of diabetic nephropathology and correlates with renal function. Functional studies are not indicative of underlying renal pathology except relatively late, when glomerular injury is advanced. Microalbuminuria in the 'predictive' range (greater than 30 micrograms/min) and associated with hypertension and/or declining GFR is a marker of established diabetic glomerulopathy. Only carefully designed longitudinal studies of renal morphology and function with accurate blood pressure monitoring beginning early in the course of IDDM will clarify the relationships between blood pressure and renal damage in IDDM. In NIDDM the frequent presence of non-diabetic renal lesions, of hypertension at or before the onset of diabetes, and the relative paucity of clinical-pathological correlations currently make it difficult to understand the role of hypertension in the genesis and progression of nephropathy. Again, longitudinal studies of blood pressure and renal structure and function are required in NIDDM patients. Finally, animal models of hypertension and diabetes may aid progress in these areas.
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PMID:Hypertension and diabetic renal disease. 179 13

The pathophysiological connections between insulin resistance, hypertension and type 2 diabetes are discussed in this review article. Increased blood pressure levels are often found in type 2 diabetic patients long before the diabetes itself is diagnosed. By contrast, in type 1 diabetes hypertension is predominantly the consequence of diabetic glomerulopathy. Non-pharmacological strategies should be favoured in the treatment of hypertension in type 2 diabetic patients before specific pharmacological intervention is started. Antihypertensive treatment with beta-blocking agents and diuretics is criticized by many experts in the field of metabolic disorders, since these drugs induce a deterioration of glycaemic control and lipid metabolism in diabetic patients. Since calcium channel blockers, ACE inhibitors and alpha 1-specific blocking agents have no influence on metabolism, these drugs are recommended for the antihypertensive treatment of diabetic patients. Further studies should be undertaken to clarify, whether ACE-inhibitors have a specific nephroprotective effect. Since most type 2 diabetic patients do not develop diabetic nephropathy, a possible nephroprotective effect of ACE inhibitors is only relevant to the antihypertensive treatment of type 1 diabetic patients.
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PMID:[Hypertension, insulin resistance and diabetes mellitus: pathophysiological interactions and therapeutic consequences]. 198 Jul 67

At present the pathogenesis of diabetic nephropathy remains unresolved. Clearly lack of insulin, with its associated disorders of carbohydrate, protein, and/or lipid metabolism, initiates the process which eventually leads to the characteristic histologic picture of diabetic nephropathy. The disturbance in cellular metabolism per se could directly injure the kidney by altering the energy needs of the cell or by leading to the accumulation of cellular toxins (ie, polyols) or by causing the deficiency of key cellular metabolites (ie, myoinositol). Elevation of the plasma glucose concentration enhances the glycosylation of proteins, which in turn can lead to glomerular basement membrane thickening, loss of charge selectivity, and direct cellular damage. The multiple disturbances in intermediary metabolism are associated with increased levels of and/or enhanced sensitivity to a variety of growth factors, including IGF-I and angiotensin, and this could lead to glomerular hypertrophy. An increase in the filtered load and subsequent reabsorption of electrolytes and metabolites also could contribute to renal hypertrophy. In all animal models of nephropathy, including diabetes, glomerular hypertrophy has been shown to be the best correlate of glomerular sclerosis, proteinuria, and progressive renal deterioration. The potential mechanisms by which glomerular hypertrophy can lead to renal histologic damage were discussed previously. By increasing the luminal diameter, glomerular hypertrophy also would be expected to augment wall tension and thereby increase intraglomerular pressure. Derangements in cellular metabolism or altered sensitivity to angiotensin also can directly elevate the intraglomerular pressure and lead to structural renal damage. In this schema, elevated intraglomerular pressure is but one of many pathogenic factors that contribute to the development of diabetic glomerulopathy and albuminuria. The precise role of increased glomerular pressure in the evolution of diabetic nephropathy remains uncertain at present. In rats, severe diabetic nephropathy can occur without an increase in Pgc, while in humans, hyperfiltration does not appear to be a predictor of proteinuria and renal dysfunction. Lastly, it is likely that a variety of other factors, including the coagulation system, plasma/cell lipid levels, prostaglandins, etc, also play a role in the pathogenesis of diabetic nephropathy. According to the outline presented in Figure 1, it is unlikely that any single factor will be sufficient to explain the development of diabetic glomerulosclerosis. Ultimately, the origin of diabetic nephropathy in IDDM must be traced to insulin lack, with its associated derangements in cellular metabolism. Therefore, the importance of tight glucose control should not be underemphasized.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Hyperfiltration and diabetic nephropathy: is it the beginning? Or is it the end? 219 Feb 80

Glomerular volume was estimated in 20 type 2 diabetic patients (age 64 +/- 6 years, duration of diabetes 6 +/- 5 years) compared with 14 sex- and age-matched controls, as well as in a group of 11 very long-term type 1 diabetic patients (age 61 +/- 12 years, duration of diabetes 44 +/- 11 years). One whole autopsy kidney was obtained prospectively, and a known fraction (approximately equal to 1/140) was sampled systematically and embedded in plastic (JB-4 glycolmetacrylate), thereby essentially eliminating shrinkage. Sections 15-microns thick were stained with periodic acid-Schiff. Mean glomerular volume was estimated on a random sample of glomeruli using the disector method. Frequency of glomerular occlusion and mean volume of open glomeruli was estimated. Mean glomerular volume was not different between type 2 diabetic patients and controls (5.3 +/- 1.7 M mu3/1.73 m2 versus 5.3 +/- 1.9 M mu3/1.73 m2) nor was total glomerular volume or kidney weight. Frequency of glomerular occlusion was 4.8 +/- 5.7% in controls, 8.9 +/- 7.8% (p = 0.10) in type 2 patients, and 16.8% +/- 20.7 (p less than 0.05) in type 1 patients. In type 2 patients there was a correlation between frequency of glomerular occlusion and mean volume of open glomeruli (r = 0.44, p = 0.05), and the same tendency was seen in type 1 patients (r = 0.49, p = 0.12). By the present method the absolute level of glomerular volume was increased by at least a factor of two compared with previous studies. This illustrates the problems arising from shrinkage of tissue in paraffin and stresses the importance of using an unbiased stereological method. The lack of increase in total glomerular volume is in accordance with clinical findings of lack of glomerular hyperfiltration in type 2 patients, findings in contrast to those in type 1 diabetes. It is suggested that hyperfiltration per se is not the cause of glomerulopathy.
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PMID:Glomerular volume in type 2 (noninsulin-dependent) diabetes estimated by a direct and unbiased stereologic method. 229 56

The mutual relationship between elevated blood pressure and structural changes in the kidney is still an area with more open questions than clear answers. Indirect evidence is available concerning one aspect: When hypertension is present it has a significant impact on the further progression of the structural changes. This evidence is available only in terms of the effect of antihypertensive treatment on the preservation of renal function. Since it has been shown that the demise in renal function in long-term diabetics is closely related to the development of advanced diabetic glomerulopathy, it seems likely that normalization of the blood pressure leads to a slowing of this development. Structural studies to elucidate these interactions are, however, not available. An intriguing question is whether the relationship is interactive also in the other direction. Focusing on the alterations within the glomeruli, the fact is that the glomerulopathy develops over several years before it come to the stage when clinical signs appear. Thus, diabetics with "incipient nephropathy" clearly demonstrate basement membrane (BM) accumulation, showing as increased BM-thickness and increase in mesangial matrix volume. Since this is the most likely point of time for hypertension to develop the necessary condition obtains, that the development of hypertension might be triggered by structural abnormalities in the kidney. The mechanisms of action at this point of time remain speculative. The relationship between structural parameters characterizing diabetic glomerulopathy and the blood pressure level was studied in a series of 14 IDDM patients, representing a span of renal functional impairment. Mean blood pressure in the group was 117 mmHg, with a range from 87-122 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Morphology of diabetic glomerulopathy and relationship to hypertension. 269 44

Hyperfiltration is a very characteristic feature in insulin-dependent diabetes. Hyperfiltration is to some extent associated with long-term glycemic control but the correlation is not very strong. Long-term hyperfiltration may play a role in the genesis of late diabetic nephropathy, but it is difficult to distinguish effects of hyperfiltration per se from effects of poor metabolic control. Long-term hyperfiltration without diabetes does not produce nephropathy. It is hypothesized that IDDM patients who do not show considerable hyperfiltration in spite of poor metabolic control may be those who are to some extent protected against late diabetic nephropathy, but other mechanisms may also be involved in the renal protection of these patients, who survive long-term diabetes without nephropathy. On the other hand, those with poor metabolic control combined with hyperfiltration are likely to develop nephropathy. In addition, it is suggested that the metabolic aberrations in diabetes, with the subsequent changes in the biochemistry of the glomerular wall, are permissive and absolutely required for the development of diabetic nephropathy. Of note, diabetic glomerulopathy in NIDDM occurs without significant hyperfiltration and extreme hyperfiltration in the one-kidney-model (without diabetes) does not produce nephropathy. Nonglycemic modalities of intervention, resulting in reduced hyperfiltration, e.g., low-protein diet or administration of somatostatin analogues, deserves interest as new potential ways of preventing or postponing diabetic nephropathy. Also intervention with aldose-reductase inhibitors may be an important therapeutic modality for those patients in whom good metabolic control is not obtainable. It is now well-established that antihypertensive treatment, including ACE-inhibition, reduces rate of decline in GFR in patients with already established nephropathy. In addition, protein excretion is diminished in IDDM patients with incipient diabetic nephropathy by antihypertensive treatment where GFR is well-preserved during treatment. No data are available for NIDDM.
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PMID:Comparative renal pathophysiology relevant to IDDM and NIDDM patients. 306 56

The prevalence of hypertension in diabetes is significantly higher than in non-diabetics, perhaps twice as common. The excess is related to diabetic nephropathy, mainly in type 1 diabetes, to obesity, mainly in type 2 diabetes, but also to increased sympathetic activity. Furthermore, the increased prevalence of hypertension may relate to insulin resistance and its sequelae. Insulin resistance leads to hyperinsulinemia, relates to increased LDL and reduced HDL levels, causes the development of impaired glucose tolerance and type 2 diabetes and might also be causally related to the onset of hypertension. Syndrome X has relevant therapeutic implications in the management of hypertension. Hypertension is a major risk factor for large vessel disease in diabetics and also a risk factor for microangiopathy, particularly nephropathy. The incidence of atherosclerotic disease is dramatically increased in both type 1 and type 2 diabetics and is the major cause of morbidity and premature death mainly in patients with raised urinary albumin excretion. Thus, diabetics show a two-fold increased risk of coronary heart disease, 2-6 fold increased risk of stroke and a several-fold increased risk of peripheral vessel disease. Some evidence suggests that hypertension may be a risk factor for retinopathy, particularly its progression, but surely hypertension is a significant risk factor for nephropathy, accelerating its progression and perhaps even causing the onset of the glomerulopathy. The mechanisms by which hypertension might contribute to the evolution of both large vessel as well as small vessel disease is still unknown, although increased capillary leakage and vascular endothelium alterations might be important factors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Hypertension and diabetes]. 856 58

A rate of albumin excretion rate above 20 micrograms/min is a predicting factor of overt nephropathy in Type I diabetes. It has not yet been established whether this is the case also for Type II diabetes, where microalbuminuria is antecedent to general and cardiovascular mortality but not to end-stage renal disease. The reasons accounting for this discrepancy between Type I and Type II diabetes have not been fully elucidated. In principle two different hypotheses can be postulated to explain these findings. Firstly it can be suggested that overt proteinuria is not detected with similar incidence rates in microalbuminuric patients with the two types of diseases because Type II diabetics are older and more prone to develop cardiovascular events. Therefore these patients would die frequently before developing overt proteinuria not because microalbuminuria is not a predicting factor of End-stage Renal Disease, but rather because the follow-up period is not long enough to monitor the patients till the very moment they develop renal complications. Alternatively it is possible that microalbuminuria reflect a systemic, endothelial and vascular disorder rather than glomerular structural abnormalities in these patients. We have recently described a clustering of clinical features encompassing microalbuminuria, hypertension, peripheral extrahepatic insulin resistance, renal and cardiac hypertrophy and altered cation membrane transport systems, not in the overall Type II diabetic population, but only in a cohort of these patients. Evidences in keeping with a strict association between insulin resistance, hypertension and microalbuminuria in a subgroup of Type II diabetic patients have been recently reported by several authors both in cross-sectional and longitudinal studies. However the hypothesis that microalbuminuria reflects a systemic endothelial and vascular disorder in Type II diabetic patients, does not rule out the possibility that these systemic disturbances are also associated with histologic abnormalities of the kidney. With regard to the characteristics of renal histology in Type II diabetic patients with and without microalbuminuria, preliminary data from our laboratory demonstrate that there is no evidence of any renal disorder other than diabetes in microalbuminuric Type II diabetic patients. More particularly in this subset of patients we observed typical features of diabetic nephropathology (glomerular, tubulo-interstitial and arteriolar changes), while a substantial number of patients with increased albumin excretion rate exhibited either marked tubulo-interstitial lesions or arteriolar hyalinosis or both, in absence of significant glomerular changes. These findings suggest that it is not true that Type II diabetic patients with microalbuminuria show quite often normal renal histology, but rather than hyperglycemia may cause different patterns of renal injury as compared to Type I Diabetes. Furthermore always with regard to renal histology, it has been pointed out that in Type I diabetes glomerulopathy (especially mesangial) is the crucial change, whereas recent studies found considerable structural heterogeneity amongst proteinuric Type II diabetic patients with relatively high incidence of renal diseases other than diabetes. However parallel studies in a small group of micromacroalbuminuric Type II diabetic patients reported the typical glomerular changes, usually shown by Type I diabetic patients with similar patterns of renal damage. The issue of the relationships between microalbuminuria, hypertension and the development of overt nephropathy in Type II diabetes has been also examined in Pima Indians. The clinical scenario found in these patients does closely resemble that of Caucasian Type I diabetic patients.
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PMID:Relationships among microalbuminuria, insulin resistance and renal-cardiac complications in insulin dependent and non insulin dependent diabetes. 928 31

We have recently described heterogeneity in renal structure in non-insulin-dependent diabetic patients (NIDDM) with microalbuminuria (MA; defined as albumin excretion rate from 20 to 200 micrograms/min). Thus, at variance with IDDM patients, "typical" diabetic glomerulopathy by light microscopy is observed only in a third of NIDDM with MA (Category II, CII). Further, despite persistent MA, 30% of NIDDM have normal or near normal renal structure (Category I, CI). Another one-third shows "atypical" patterns of renal injury with absent or mild diabetic glomerular changes, associated with disproportionately severe tubulointerstitial lesions and/or arteriolar hyalinosis and global glomerular sclerosis (Category III, CIII). The aims of this study were to evaluate whether similar patterns of renal lesions could be confirmed in a larger group of NIDDM with MA and to investigate tubular function in order to understand the mechanisms underlying MA in NIDDM patients. Renal biopsies were performed in 53 NIDDM with MA. Categories I, II and III were found in 41%, 26% and 33% of NIDDM with MA, respectively. All 8 patients with proliferative diabetic retinopathy were in CII. We also studied the urinary daily excretion rate of alpha 1-microglobulin (alpha 1 m), a low molecular weight protein, which is a useful indicator of tubular function. alpha 1 m was markedly increased only in CII patients (CI vs. CII vs. CIII: 6.2 +/- 1.2 vs. 13.7 +/- 2.1 vs. 7.3 +/- 0.9 mg/day, ANOVA, P < 0.01). In conclusion, we confirm that there is heterogeneity in renal structure in NIDDM patients with MA. This heterogeneity is not due to renal diseases other than diabetes. Increased alpha 1 m and proliferative retinopathy are useful indicators of the subgroup of MA NIDDM patients with typical diabetic glomerulopathy. It is suggested that diabetic microangiopathy explains the simultaneous occurrence of typical diabetic glomerulopathy, proliferative retinopathy and tubular dysfunction in a subgroup of NIDDM patients with MA.
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PMID:Renal structure and function in non-insulin dependent diabetic patients with microalbuminuria. 940 19


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