Abnormalities in plasmas concentrations of lipoproteins and fibrinogen in type 1 (insulin-dependent) diabetic patients with increased urinary albumin excretion

Reversal of hypertriglyceridemia in diabetic BTBR ob/ob mice does not prevent nephropathy

The etiology of diabetic nephropathy in type 2 diabetes is multifactorial. Sustained hyperglycemia is a major contributor, but additional contributions come from the hypertension, obesity, and hyperlipidemia that are also commonly present in patients with type 2 diabetes and nephropathy. The leptin deficient BTBR ob/ob mouse is a model of type 2 diabetic nephropathy in which hyperglycemia, obesity, and hyperlipidemia, but not hypertension, are present. We have shown that reversal of the constellation of these metabolic abnormalities with leptin replacement can reverse the morphologic and functional manifestations of diabetic nephropathy. Here we tested the hypothesis that reversal specifically of the hypertriglyceridemia, using an antisense oligonucleotide directed against ApoC-III, an apolipoprotein that regulates the interactions of VLDL (very low density lipoproteins) with the LDL receptor, is sufficient to ameliorate the nephropathy of Type 2 diabetes. Antisense treatment resulted in reduction of circulating ApoC-III protein levels and resulted in substantial lowering of triglycerides to near-normal levels in diabetic mice versus controls. Antisense treatment did not ameliorate proteinuria or pathologic manifestations of diabetic nephropathy, including podocyte loss. These studies indicate that pathologic manifestations of diabetic nephropathy are unlikely to be reduced by lipid-lowering therapeutics alone, but does not preclude a role for such interventions to be used in conjunction with other therapeutics commonly employed in the treatment of diabetes and its complications.

Hesperidin, a citrus flavonoid ameliorates hyperglycemia by regulating key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats

The present study investigated the protective effect of hesperidin on carbohydrate metabolizing enzymes in streptozotocin-induced diabetic rats. Hesperidin was administered to streptozotocin-induced (40 mg/kg b.w.) diabetic rats at different dosages of (25, 50, 100 mg/kg b.w.) respectively for 30 days to evaluate its effect on fasting plasma glucose, insulin, glycosylated hemoglobin, hemoglobin, and carbohydrate metabolic enzymes. The plasma glucose levels were significantly reduced in a dose-dependent manner in hesperdin-treated group of rats when compared to the diabetic control rats. In addition, concomitant increase in hemoglobin and insulin levels and a decrease in glycosylated hemoglobin were observed in treated group of rats. The activities of the hepatic key enzymes of carbohydrate metabolism such as hexokinase and glucose-6-phosphate dehydrogenase were significantly increased, whereas glucose-6-phosphatase and fructose-1,6-bisphosphatase were significantly decreased. Furthermore, hesperidin administration prevented the loss in body weight and improved the glycogen content in the hepatic tissue of diabetic animals by reinstating the activities of glycogen synthase and glycogen phosphorylase. These results showed that hesperidin has potential antihyperglycemic activity in streptozotocin-induced diabetic rats. This was further supported by the histological studies of pancreas and liver.

Associations between serum apolipoproteins, urinary albumin excretion rate, estimated glomerular filtration rate, and diabetic retinopathy in individuals with type 2 diabetes

The published data regarding the role of serum apolipoprotein (apo) A-I, apoB, and the apoB/A-I ratio in the risk of diabetic retinopathy remain inconsistent, and there is limited information about the effect of renal status on their associations in individuals with type 2 diabetes. The aim of this study was to investigate whether serum apoA-I, apoB, and the apoB/A-I ratio are associated with the presence of diabetic retinopathy in type 2 diabetes and to explore whether the relationships between these apolipoproteins and diabetic retinopathy are modified by urinary albumin excretion rate (UACR) and estimated glomerular filtration rate (eGFR).In total, 1215 individuals with type 2 diabetes were included in this cross-sectional study. Serum levels of apoA-I and apoB and the apoB/apoA-I ratio were measured. A logistic regression model was performed to explore associations of apolipoproteins with retinopathy.Individuals with diabetic retinopathy had significantly lower levels of serum apoA-I and higher apoB/apoA-I ratio than those without diabetic retinopathy. In the multivariable analyses, the associations between apoA-I and diabetic retinopathy and between the apoB/apoA-I ratio and diabetic retinopathy were statistically significant after adjustment for the traditional risk factors (odds ratio [OR] per standard deviation [SD] increase in the log-transformed value; 0.55, 95% confidence interval (CI); 0.32 to 0.97, P = .038; OR per SD increase in the log-transformed value; 2.83, 95% CI; 1.18 to 6.76, P = .019; respectively). Additional adjustments for UACR or eGFR removed the significant associations.In individuals with type 2 diabetes, serum apoA-I and the apoB/apoA-I ratio are associated with presence of diabetic retinopathy, which might be attributable to the correlated changes in UACR and eGFR.

Effects of Resveratrol and Mangiferin on PPARγ and FALDH Gene Expressions in Adipose Tissue of Streptozotocin-Nicotinamide-Induced Diabetes in Rats

Type 2 diabetes (T2D) is characterized by insufficient insulin secretion by the pancreatic beta cells and insulin resistance in liver, skeletal muscle, and white adipose tissue. Adipose tissue plays a major role in glucose homeostasis and lipid metabolism. Dietary antioxidants such as resveratrol and mangiferin may offer some protection against the early stage of diabetes mellitus. Therefore, an attempt has been made to investigate the effects of resveratrol and mangiferin on biochemical parameters and molecular mechanism of PPARγ and FALDH gene expression in adipose tissue of streptozotocin- (STZ-) nicotinamide- (NA-) induced diabetic rats. Albino Wister rats were randomly divided into five groups: control rats (Group 1), diabetic control rats (Group 2), diabetic rats given resveratrol (40 mg/kg body weight per day; Group 3), diabetic rats given mangiferin (40 mg/kg body weight per day; Group 4), diabetic rats given glibenclamide (0.6 mg/kg body weight per day; Group 5). Serum biochemical parameters-total cholesterol (TC), total triglyceride (TG), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, glycosylated hemoglobin (HbA1c), urea, and uric acid were analyzed. We found that the oral administration of resveratrol and mangiferin to STZ-NA-induced diabetic rats for 30 days showed the significant protective effect on all the biochemical parameters. A significant reduction in blood glucose and HbA1c levels was observed in rats treated with 40 mg/kg body weight per day of resveratrol or mangiferin. Moreover, both these antioxidants showed significant enhancement of PPARγ and FALDH gene expression in rat adipose tissue compared to control rats.

Isolated flavonoids from Ficus racemosa stem bark possess antidiabetic, hypolipidemic and protective effects in albino Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ficus racemosa (FR) has been used for thousands of years in Ayurvedic system of medicine in India and is closely associated with prevention, treatment and cure of various human ailments like obesity and diabetes. It is popularly known as gular. A vast and wide range of chemical compounds like polyphenols, friedelane-type triterpenes, norfriedelane type triterpene, eudesmane-type sesquiterpene including various glycosides had been isolated from this plant. However, no detail studies related to isolation of flavonoids has been reported previously with their antidiabetic, hypolipidemic and toxicological consequences.

AIM OF THE STUDY

The present study was undertaken to evaluate antidiabetic, hypolipidemic and toxicological assessments of flavonoids isolated from Ficus racemosa (FR) stem bark.

MATERIALS AND METHODS

We isolated four flavonoids from stem bark of FR and structures were confirmed by Infrared spectroscopy (IR), Nuclear Magnetic Resonance (NMR) (both 1D and 2D), mass spectroscopy (MS). Later, these flavonoids were administered to streptozotocin (STZ) rats once in a day for a period of seven days at 100mg/kg dose. We measured blood glucose level and body weight changes at different days (1st, 3rd, 5th and 7th days). Serum lipid profiles were also estimated to investigate the hypolipidemic potential of flavonoids in the similar experiment. Various oxidative stress parameters in pancreas and liver and hepatic biomarker enzymes in plasma were also determined to investigate the toxicity potential of isolated flavonoids. Finally, we performed docking studies to find out the mechanism of action.

RESULTS

Our results collectively suggested that four flavonoids reduced blood glucose level and restored body weight, signifying antidiabetic action. There were reduction of other lipid profile parameters and increase of high density lipoprotein (HDL) during administration of flavonoids, also signifying hypolipidemic action. Various oxidative stress biomarkers and hepatic enzymes levels were also normalized with respect to diabetic control at the same time. Docking studies revealed that isolated flavonoids showed their antidiabetic potential via binding to PPARγ and GLUT1 receptors.

CONCLUSION

The isolated four flavonoids demonstrated good antidiabetic, hypolipidemic and antioxidant properties in STZ diabetic rats which supported the use of FR stem bark as useful supplementary drug for future antidiabetic therapy.

Attenuation of hepatotoxicity and oxidative stress in diabetes STZ-induced type 1 by biotin in Swiss albino mice

Diabetes mellitus is one of the major health problems. This study was designed to investigate the effect of biotin to regulate blood glucose level, reduced toxicity and oxidative stress in liver of diabetic mice STZ-induced type 1. Male mice were divided into three groups, the first one served as the control group, the second and the third groups received single ip dose of 150 mg/kg of STZ, the second group served as the untreated diabetic group, the third group received daily oral dose of 15 mg/kg of biotin, livers and liver index showed insignificant difference among groups. Blood glucose level showed a significant decrease in treated diabetic mice compared to untreated diabetic mice. Biochemical analysis showed a significant decrease in liver enzymes AST and ALT compared to the control group. Histopathological examination showed severe changes in untreated diabetic liver tissue manifested by dilated portal vein, leukocytic infiltration, fatty degeneration and moderate to severe histopathological score, whereas, treated diabetic mice with biotin showed reduction in hepatotoxicity represented by appearance of relative healthy hepatocytes and normal histopathological score. Immunohistochemistry of acrolein showed intense immunoreactions in liver section of untreated diabetic mice and faint immunoreactions in treated diabetic mice with biotin as evidence to oxidative stress reduction.

Fibrin clot properties and haemostatic function in men and women with type 1 diabetes

The increased risk of vascular complications in type 1 diabetes may in part be explained by changes in haemostatic function. In the present study, we investigated the fibrin clot properties in patients with type 1 diabetes in relation to sex and microvascular complications. The study included 236 patients (107 women) aged between 20-70 years and without any history of cardiovascular disease. Fibrin clot properties, assessed by determination of the permeability coefficient (Ks) and turbidimetric clotting and lysis assays, did not differ between men and women. Compared with men, women had worse glycaemic control as well as higher levels of prothrombin fragment 1+2 and peak thrombin generation in vitro, indicating increased thrombin generation both in vivo and in vitro. Subgroup analyses of patients younger than 30 years revealed less permeable fibrin clots and prolonged lysis time in females compared with age-matched men. Patients with microvascular complications had higher fibrinogen concentrations and denser and less permeable fibrin clots. Thus, we conclude that in vitro fibrin clot properties in patients with type 1 diabetes without cardiovascular disease are not different between the sexes, but associate with prevalence of microvascular complications. Tighter fibrin clot formation in younger women, as suggested by our results, may affect their future cardiovascular risk and should be investigated in a larger population.

Small dense low-density lipoprotein as a potential risk factor of nephropathy in type 2 diabetes mellitus

BACKGROUND

The risk for diabetic nephropathy in type 2 diabetes is about 30-40%, and it is considered the leading cause of end-stage renal disease. Small dense low-density lipoprotein (sdLDL) particles are believed to be atherogenic, and its predominance has been accepted as an emerging cardiovascular risk factor. This study aimed to assess small dense LDL as a potential risk factor and a possible predictor for diabetic nephropathy in type 2 diabetic patients.

PATIENTS AND METHODS

According to microalbuminuria test, 40 diabetic patients were categorized into two groups: Diabetic patients without nephropathy (microalbuminuria negative group) and diabetic patients with nephropathy (microalbuminuria positive group), each group consists of 20 patients and all were non-obese and normotensive. The patients were re-classified into three sub-groups depending on the glomerular filtration rate (GFR).

RESULTS

The mean of small dense LDL level in the microalbuminuria positive group was higher than that in the microalbuminuria negative group, but without statistical significance. It was significantly higher in patients with either mild or moderate decrease in estimated GFR than in patients with normal estimated GFR. There was statistically significant correlation between small dense LDL and albuminuria and significant inverse correlation between small dense LDL and estimated GFR in all patients in the study. Based on microalbuminuria, the sensitivity and specificity of small dense LDL in the diagnosis of diabetic nephropathy was 40% and 80%, respectively, with cutoff values of small dense LDL >55.14 mg/dl. On the other hand, based on GFR, the sensitivity and specificity were 88.24% and 73.91% respectively, with cutoff values of small dense LDL >41.89 mg/dl.

CONCLUSION

Small dense LDL is correlated with the incidence and severity of diabetic nephropathy in type 2 diabetic patients. It should be considered as a potential risk factor and as a diagnostic biomarker to be used in conjunction with other biochemical markers for early diagnosis, assessment, and follow-up of diabetic nephropathy.

Effects of zinc supplementation on the element distribution in kidney tissue of diabetic rats subjected to acute swimming

In this study, we report the effect of zinc supplementation on the distribution of elements in kidney tissue of diabetic rats subjected to acute swimming exercise. Diabetes was induced by two subcutaneous injections of 40 mg/kg of streptozotocin within a 24-h period. Zinc was given intraperitoneally at a dose of 6 mg/kg per day for a period of 4 weeks. The rats (n = 80) were equally divided into eight study groups: controls, zinc-supplemented, swimming, diabetic, zinc-supplemented diabetic, zinc-supplemented swimming, diabetic swimming, and zinc-supplemented diabetic swimming. The levels of lead, cobalt, molybdenum, chromium, boron, magnesium, iron, copper, calcium, zinc, and selenium were determined in the kidney tissue samples by ICP-AES. Higher molybdenum, calcium, zinc, and selenium values were found in both swimming and nonswimming diabetic rats. Significantly higher iron values were found in swimming, diabetic, diabetic swimming, and zinc-supplemented diabetic swimming rats (p < 0.001). Diabetic, zinc-supplemented diabetic, diabetic swimming, and zinc-supplemented diabetic swimming rats had the highest copper values. These results show that zinc supplementation normalized the higher levels of molybdenum, calcium, selenium, and iron levels seen in diabetic rats, indicating that zinc may have a regulatory effect on element metabolism in kidney tissue.

Effect of an isolated active compound (Cg-1) of Cassia glauca leaf on blood glucose, lipid profile, and atherogenic index in diabetic rats

Objectives:

The objective of present study was to evaluate the effect of active principle (Cg-1) from Cassia glauca leaf on serum glucose and lipid profile in normal and diabetic rats.

Materials and Methods:

Diabetes was induced by streptozotocin in neonates. Oral administration of petroleum ether, chloroform, acetone, and methanol of C. glauca leaf (100 mg/kg, p.o.) for 21 days caused a decrease in fasting blood glucose (FBG) in diabetic rats. Among all the extracts, acetone extract was found to lower the FBG level significantly in diabetic rats. Glibenclamide was used as standard antidiabetic drug (5 mg/kg, p.o). Acetone extract was subjected to column chromatography that led to isolation of an active principle, which was given trivial name Cg-1. Cg-1 (50 mg/kg, p.o.) was studied for its hypoglycemic and hypolipidemic potential. The unpaired t-test and analysis of variance (ANOVA) followed by post hoc test was used for statistical analysis.

Results:

Cg-1 caused a significant reduction in FBG level. It also caused reduction in cholesterol, triglycerides, and LDL levels and improvement in the atherogenic index and HDL level in diabetic rats.

Conclusion:

Improvement in the FBG and the atherogenic index by Cg-1 indicates that Cg-1 has cardioprotective potential along with antidiabetic activity and provides a scientific rationale for the use as an antidiabetic agent.

Macrovascular angiopathy in children and adolescents with type 1 diabetes

Diabetes represents one of the most common diseases globally. Worryingly, the worldwide incidence of type 1 diabetes (T1D) is rising by 3% per year. Despite the rapid increase in diabetes incidence, recent advances in diabetes treatment have been successful in decreasing morbidity and mortality from diabetes-related retinopathy, nephropathy, and neuropathy. In contrast, there is clear evidence for the lack of improvement in mortality for cardiovascular diseases (CVDs). This emphasizes the importance of focusing childhood diabetes care strategies for the prevention of CVD in adulthood. Furthermore, although most work on diabetes and macrovascular disease relates to type 2 diabetes, it has been shown that the age-adjusted relative risk of CVD in T1D far exceeds that in type 2 diabetes. As T1D appears predominantly during childhood, those with T1D are at greater risk for coronary events early in life and require lifelong medical attention. Because of the important health effects of CVDs in children and adolescents with T1D, patients, family members, and care providers should understand the interaction of T1D and cardiovascular risk. In addition, optimal cardiac care for the patient with diabetes should focus on aggressive management of traditional cardiovascular risk factors to optimize those well-recognized as well as new specific risk factors which are becoming available. Therefore, a complete characterization of the molecular mechanisms involved in the development and progression of macrovascular angiopathy is needed. Furthermore, as vascular abnormalities begin as early as in childhood, potentially modifiable risk factors should be identified at an early stage of vascular disease development.

Antihyperlipidemic activity of 3-hydroxymethyl xylitol, a novel antidiabetic compound isolated from Casearia esculenta (Roxb.) root, in streptozotocin-diabetic rats

Casearia esculenta root (Roxb.) is widely used in traditional system of medicine to treat diabetes in India. An active compound, 3-hydroxymethyl xylitol (3-HMX), has been isolated, and its optimum dose has been determined in a short duration study and patented. In addition, the long-term effect of 3-HMX in type 2 diabetic rats on carbohydrate metabolism was investigated, and its antihyperglycemic effect was shown previously (Chandramohan et al., Eur J Pharmacol 2008;590:437-443). In this study we investigated the effect of 3-HMX on plasma and tissue lipid profiles in streptozotocin-induced diabetic rats. Diabetes was induced in adult male albino rats of the Wistar strain, weighing 180-200 g, by administration of streptozotocin (40 mg/kg of body weight) intraperitoneally. The normal and diabetic rats were treated with 3-HMX (40 mg/kg BW/day) for 45 days. The levels of total cholesterol, triglycerides, free fatty acids, and phospholipids were assayed in the plasma besides lipoprotein-cholesterol (high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), and very low density lipoprotein-cholesterol (VLDL-C)) and tissues (liver, kidney, heart, and brain). Total cholesterol, triglyceride, free fatty acid, and phospholipid (LDL-C and VLDL-C in plasma only) levels increased in plasma and tissues significantly, whereas plasma HDL-C significantly decreased in diabetic rats. Treatment with 3-HMX or glibenclamide reversed the above-mentioned changes and improved toward normalcy. Histological study of liver also confirmed the biochemical findings. Thus administration of 3-HMX is able to reduce hyperglycemia and hyperlipidemia related to the risk of diabetes mellitus.

Hyperglycemia-induced alterations in synaptosomal membrane fluidity and activity of membrane bound enzymes: beneficial effect of N-acetylcysteine supplementation

Diabetic encephalopathy is characterized by impaired cognitive functions that appear to underlie neuronal damage triggered by glucose driven oxidative stress. Hyperglycemia-induced oxidative stress in diabetic brain may initiate structural and functional changes in synaptosomal membranes. The objective of the present study was to examine the neuroprotective role of N-acetylcysteine (NAC) in hyperglycemia-induced alterations in lipid composition and activity of membrane bound enzymes (Na(+),K(+)-ATPase and Ca(2+)-ATPase) in the rodent model of type 1 diabetes. Male Wistar rats weighing between 180 and 200 g were rendered diabetic by a single injection of streptozotocin (50 mg/kg body weight, i.p.). The diabetic animals were administered NAC (1.4-1.5 g/kg body weight) for eight weeks and lipid composition along with membrane fluidity were determined. A significant increase in lipid peroxidation was observed in cerebral cortex of diabetic rats. NAC administration on the other hand lowered the hyperglycemia-induced lipid peroxidation to near control levels. The increased lipid peroxidation following chronic hyperglycemia was accompanied by a significant increase in the total lipids which can be attributed to increase in the levels of cholesterol, triglycerides and glycolipids. On the contrary phospholipid and ganglioside levels were decreased. Hyperglycemia-induced increase in cholesterol to phospholipid ratio reflected decrease in membrane fluidity. Fluorescence polarization (p) with DPH also confirmed decrease in synaptosomal membrane fluidity that influenced the activity of membrane bound enzymes. An inverse correlation was found between fluorescence polarization with the activities of Na(+),K(+)-ATPase (r(2)=0.416, P<0.05) and Ca(2+) ATPase (r(2)=0.604, P<0.05). NAC was found to significantly improve lipid composition, restore membrane fluidity and activity of membrane bound enzymes. Our results clearly suggest perturbations in lipid composition and membrane fluidity as a major factor in the development of diabetic encephalopathy. Furthermore, NAC administration ameliorated the effect of hyperglycemia on oxidative stress and alterations in lipid composition thereby restoring membrane fluidity and activity of membrane bound enzymes.

Protective effect of Cassia glauca Linn. on the serum glucose and hepatic enzymes level in streptozotocin induced NIDDM in rats

OBJECTIVE

The objective of the present study was to investigate the hypoglycemic and hepatoprotective effect of Cassia glauca leaf extracts on normal and non insulin dependent diabetes mellitus (NIDDM) in rats. The study was further carried out to investigate the effect of different fractions of the active extract of Cassia glauca, on normal and NIDDM rats, and the effect of active fraction on the blood glucose and hepatic enzymes level.

METHODS

Diabetes was induced by streptozotocin (STZ) at a dose of 90mg/kg, i.p. in neonates. Different extracts of cassia glauca (100mg/kg, p.o.) were administered to the diabetic rats. Acetone extract was found to lower the serum glucose level significantly in diabetic rats. Further, the acetone extract was subjected to column chromatography and four fractions were obtained on the basis of TLC. All the four fractions (100mg/kg, p.o.) were administered to the diabetic rats. Fraction 1 (F1) caused the maximum reduction in the blood glucose level. The results of the test were compared with the standard antidiabetic drug glibenclamide (5mg/kg, p.o.).

RESULTS

Fraction 1 of acetone extract caused a significant reduction in the levels of hepatic enzyme Aspartate transaminase (AST), alanine transaminase (ALT), creatine kinase (CK), and lactate dehydrogenase (LDH) in STZ-induced diabetic rats.

CONCLUSION

Improvement in the blood sugar level and normalization of liver functions by Cassia glauca indicates that the plant has hepatoprotective potential, along with antidiabetic activity, and it provides a scientific rationale for the use of Cassia glauca as an antidiabetic agent.

Diabetes, metallothionein, and zinc interactions: a review

Epidemiological evidence, associating diabetes with zinc (Zn) deficiencies, has resulted in numerous research studies describing the effects of Zn and associated metallothionein (MT), on reducing diabetic complications associated with oxidative stress. MT has been found to have a profound effect on the reduction of oxidative stress induced by the diabetic condition. Over expression of MT in various metabolic organs has also been shown to reduce hyperglycaemia-induced oxidative stress, organ specific diabetic complications, and DNA damage in diabetic experimental animals, which have been further substantiated by the results from MT-knockout mice. Additionally, supplementation with Zn has been shown to induce in vivo MT synthesis in experimental animals and to reduce diabetes related complications in both humans and animal models. Although the results are promising, some caution regarding this topic is however necessary, due to the fact that the majority of the studies done have been animal based. Hence more human intervention trials are needed regarding the positive effects of MT and Zn before firm conclusions can be made regarding their use in the treatment of diabetes.

Subclinical coronary and aortic atherosclerosis detected by magnetic resonance imaging in type 1 diabetes with and without diabetic nephropathy

BACKGROUND

Patients with type 1 diabetes and nephropathy maintain an excess cardiovascular mortality compared with diabetic patients with normoalbuminuria. We sought to evaluate coronary and aortic atherosclerosis in a cohort of asymptomatic type 1 diabetic patients with and without diabetic nephropathy using cardiovascular magnetic resonance imaging.

METHODS AND RESULTS

In a cross-sectional study, 136 subjects with long-standing type 1 diabetes without symptoms or history of cardiovascular disease, including 63 patients (46%) with nephropathy and 73 patients with normoalbuminuria, underwent cardiovascular magnetic resonance imaging. All subjects underwent cardiac exercise testing and noninvasive tests for peripheral artery disease and autonomic neuropathy. Coronary artery stenoses were identified in 10% of subjects with nephropathy (versus 0% with normoalbuminuria; P=0.007). Coronary plaque burden, expressed as right coronary artery mean wall thickness (1.7+/-0.3 versus 1.3+/-0.2 mm; P<0.001) and maximum right coronary artery wall thickness (2.2+/-0.5 versus 1.6+/-0.3 mm; P<0.001), was greater in subjects with nephropathy. The prevalence of thoracic (3% versus 0%; P=0.28) and abdominal aortic plaque (22% versus 16%; P=0.7) was similar in both groups. Subjects with and without abdominal aortic plaques had similar coronary plaque burden.

CONCLUSIONS

In asymptomatic type 1 diabetes, cardiovascular magnetic resonance imaging reveals greater coronary plaque burden in subjects with nephropathy compared with those with normoalbuminuria.

Lipids and diabetic nephropathy

Although several factors may mediate the development and progression of diabetic nephropathy, hyperlipidemia is now considered an independent and major determinant of progression of renal disease in diabetes. The following discussion focuses on the experimental evidence that incriminates hyperlipidemia as a pathogenic factor for diabetic nephropathy and the potential mechanisms that may mediate renal injury from hyperlipidemia, as well as the clinical studies involving therapeutic interventions for hyperlipidemia and their impact on progression of diabetic renal disease.

Insulin resistance in diabetic nephropathy--cause or consequence?

Insulin resistance (IR) is associated with multiple risk factors for cardiovascular disease. Many studies have shown that IR is present in chronic renal failure (CRF), and recent evidence suggests that IR can also occur in the early stages of renal disease. Patients with diabetic nephropathy (DN) have an increase in cardiovascular mortality, and since IR may be a contributing factor, this emphasizes the importance of a detailed understanding of the mechanisms linking IR and renal dysfunction at different stages of DN. IR can be detected early on in DN, e.g. at the stage of microalbuminuria (MA) and this could indicate a common genetic trait for IR and DN. As DN progresses further, IR is aggravated and it may, in addition to other factors, possibly accelerate the decline in renal function toward end-stage renal disease (ESRD). Several potentially modifiable mechanisms including circulating hormones, neuroendocrine pathways and chronic inflammation, are said to contribute to the worsening of IR. In ESRD, uremic toxins are of major importance. In this review article, we address the association between different stages of DN and IR and attempt to summarize major findings on potential mechanisms linking DN and IR. We conclude that IR is a consequence, and potentially also a cause of DN. In addition, there are probably genetic and environmental background factors that predispose to both IR and DN.

Beneficial effects of aloe vera leaf gel extract on lipid profile status in rats with streptozotocin diabetes

The effect of diabetes mellitus on lipid metabolism is well established. The association of hyperglycaemia with an alteration of lipid parameters presents a major risk for cardiovascular complications in diabetes. Many secondary plant metabolites have been reported to possess lipid-lowering properties. The present study was designed to examine the potential anti-hyperlipidaemic efficacy of the ethanolic extract from Aloe vera leaf gel in streptozotocin (STZ)-induced diabetic rats. 2. Oral administration of Aloe vera gel extract at a dose of 300 mg/kg bodyweight per day to STZ-induced diabetic rats for a period of 21 days resulted in a significant reduction in fasting blood glucose, hepatic transaminases (aspartate aminotransferase and alanine aminotransferase), plasma and tissue (liver and kidney) cholesterol, triglycerides, free fatty acids and phospholipids and a significant improvement in plasma insulin. 3. In addition, the decreased plasma levels of high-density lipoprotein-cholesterol and increased plasma levels of low-density lipoprotein-and very low-density lipoprotein-cholesterol in diabetic rats were restored to near normal levels following treatment with the extract. 4. The fatty acid composition of the liver and kidney was analysed by gas chromatography. The altered fatty acid composition in the liver and kidney of diabetic rats was restored following treatment with the extract. 5. Thus, the results of the present study provide a scientific rationale for the use of Aloe vera as an antidiabetic agent.

Higher levels of HDL cholesterol are associated with a decreased likelihood of albuminuria in patients with long-standing type 1 diabetes

OBJECTIVE

The objective of this study was to determine whether high levels of HDL cholesterol are associated with a lower prevalence of albuminuria

RESEARCH DESIGN AND METHODS

We analyzed the lipid profiles of patients with type 1 diabetes of > or = 20 years duration in 42 patients with albuminuria (28 microalbuminuria and 14 macroalbuminuria) and 65 patients without increased albumin excretion before any interventions with either statins or ACE inhibitors.

RESULTS

Several characteristics were similar in the two groups: sex, age, duration of diabetes, total cholesterol, LDL cholesterol, and triglycerides. By univariate analysis, significant differences (P < 0.01) were found in HDL cholesterol (albuminuria 1.42 mg/dl, no albuminuria 1.71 mg/dl, P < 0.01), HbA1c (A1C) (albuminuria 8.5%, no albuminuria 7.5%), and proportions with no, background, and proliferative retinopathy (albuminuria 2.4, 16.7, and 81%; no albuminuria 24.6, 52.3, and 23.1%, respectively). When adjusted for age and sex, a 0.26-mmol/l (10-mg/dl) increase in HDL cholesterol is associated with an odds ratio (OR) of 0.70 (95% CI 0.54-0.90) for having albuminuria. In a multivariate model that adjusted for age, sex, diabetes duration, and A1C, for every 0.54-mmol/l (21-mg/dl) increase in HDL cholesterol, patients are approximately half (OR 0.51 [95% CI 0.30-0.86]) as likely to have albuminuria, even after controlling for A1C.

CONCLUSIONS

Higher HDL cholesterol levels may be protective against the development of albuminuria in patients with type 1 diabetes. Whether this is due to the HDL cholesterol levels or whether they serve as a marker for some other mechanism remains to be determined.

Incidence of microalbuminuria in tobacco chewers

It is well established that smoking increases the risk for cardiovascular disease. From the studies in diabetic subjects it has been shown that smoking induces microalbuminuria and accelerates the progression to end stage renal disease. Little is known whether smoking is also related to microalbuminuria and renal end organ damage in non diabetic subjects. The hypothesis which was put forward that tobacco chewing is related to microalbuminuria and renal functional changes in non diabetic subjects. We therefore performed a population based study in the Anand city of Gujarat in which we studied the relation between tobacco chewing and urinary albumin excretion. Tobacco chewers had a higher urinary albumin excretion (Albumin excretion 373±13.9 mg/day: P<0.01) than those who do not consume tobacco. In conclusion tobacco chewing is associated with albuminuria.

Cardiovascular disease morbidity and mortality in patients with type 1 diabetes mellitus : management strategies

There is an increased risk of cardiovascular disease (CVD) mortality and morbidity in patients with type 1 diabetes mellitus compared with the general population as shown by epidemiologic studies measuring cardiovascular endpoints, as well as by autopsy, angiographic, and coronary calcification studies. Most of the excess CVD risk associated with type 1 diabetes is concentrated in the subset of approximately 35% of patients who develop diabetic nephropathy (after 20 years of diabetes duration), who also typically have dyslipidemias, elevated blood pressure, and hyperglycemia, factors contributing to CVD. For reasons that remain speculative, the relative risks from CVD are higher in women than in men with type 1 diabetes compared with the general population, which effectively eliminates the gender differences in CVD. As in the general population and in patients with type 2 diabetes, education and lifestyle changes, interventions to reduce hyperglycemia, blood pressure, micro-albuminuria, lipid control, and the use of aspirin are important management areas in order to reduce the increased risk of CVD. Whether management with aspirin and statins should be started in type 1 diabetic patients at a younger age or at a lower risk score than in the general population is still under investigation. There is a need for a better understanding of the pathophysiology of vascular complications in type 1 diabetes, more specific risk engines in type 1 diabetes, and accurate estimations of the absolute and relative risk for CVD in order to improve management of CVD in these high-risk patients.

Elevated placental growth factor (PlGF) predicts cardiovascular morbidity and mortality in type 1 diabetic patients with diabetic nephropathy

BACKGROUND AND AIM

Placental growth factor (PlGF) is up-regulated in early and advanced atherosclerotic lesions, acts as a primary inflammatory instigator of atherosclerotic plaque instability, and may be an independent biomarker of adverse outcome in patients with acute coronary syndromes. In diabetic nephropathy the relative cardiovascular mortality and morbidity is increased and therefore, this study investigated the prognostic value of PlGF in a large cohort of type 1 diabetic patients with and without diabetic nephropathy.

RESEARCH DESIGN AND METHODS

In a prospective, observational follow-up study 190 type 1 diabetic patients with overt diabetic nephropathy (116 men, age (mean (SD)) 41+/-10 years, duration of diabetes 28+/-8 years, glomerular filtration rate (GFR) 76+/-33 mL/min/1.73 m2) and a matched control group of 174 patients with normoalbuminuria (104 men, age 43+/-10 years, duration of diabetes 27+/-9) were followed for 10 years (range: 0-10.3). The primary endpoint was a composite endpoint of cardiovascular death, hospitalization for myocardial infarction or stroke, coronary artery bypass grafting or percutanous coronary intervention, ischaemic amputation or peripheral bypass-surgery. Plasma PlGF was determined by an enzyme linked immunosorbent assay at baseline.

RESULTS

During 10 years of follow-up 74 patients (39%) with diabetic nephropathy reached the primary endpoint versus only 18 (10%) of normoalbuminuric patients, log rank test; p<0.001. During follow-up 16 (25%) patients in the lowest, 24 (39%) in the middle and 34 (52%) patients in the upper tertile reached the primary cardiovascular endpoint, p=0.007. Hazard ratios in the second and third tertile as compared with the first tertile were 1.76 (0.92-3.38) and 2.64 (1.41-4.91) (p=0.009). Cox regression analyses including PlGF concentration as a continuous variable revealed an unadjusted hazard ratio of the primary endpoint for each 1 ng/L increase in PlGF of 1.10 (1.03-1.16), p=0.002; covariate adjusted hazard ratio 1.07 (1.00-1.14), p=0.03.

CONCLUSIONS

Increased PlGF is a new independent predictor of cardiovascular morbidity and mortality in type 1 diabetic patients with diabetic nephropathy.

Increased plasma glycated low-density lipoprotein concentrations in diabetes: a marker of atherogenic risk

Nonenzymatic glycation of apolipoprotein B in the low-density lipoprotein (LDL) complex has been considered a proatherogenic modification contributory to the increased susceptibility of patients with diabetes to atherosclerosis. We postulated that glycated LDL concentrations might be associated with other markers of cardiovascular disease. To explore this hypothesis, we measured glycated LDL concentrations by a monospecific immunoassay in 50 patients with type 1 and 100 patients with type 2 diabetes and examined relationships with the amount of albumin excretion and the serum cholesterol and triglyercide concentrations. Plasma glycated LDL showed a significant positive correlation (r = 0.325; P < 0.001) with urinary albumin excretion that was higher in type 1 (r = 0.463) than in type 2 (r = 0.245) patients. The mean glycated LDL concentration progressively increased with increasing albumin excretion when patients were subcategorized into groups of normoalbuminuria, low (</=100 microg/mg of creatinine), and high (101-300 microg/mg) microalbuminuria, and proteinuria. Glycated LDL also correlated positively and significantly with cholesterol (r = 0.578) and triglyceride (r = 0.350) concentrations. The significant correlations in this cross-sectional analysis between glycated LDL and urinary albumin excretion, an index of cardiovascular mortality, and cholesterol and triglyceride concentrations, traditional markers of risk for cardiovascular disease, support the hypothesis that an elevated level of glycated LDL represents an atherogenic risk factor in patients with diabetes.

Marcadores de inflamação em pacientes com Diabetes Mellitus tipo 1

Para avaliar a resposta inflamatória, representada pelas proteínas de fase aguda, estudamos 48 pacientes com diabetes tipo 1 (DM1) sem complicações [23F:25M; 19,9±9,8 anos e 5 (1-21) anos de duração da doença& e 66 indivíduos sem DM, pareados quanto ao sexo, idade e estadiamento puberal (critérios de Tanner). Foram dosadas proteína C reativa (PCR), alfa1-glicoproteína ácida (alfa-1GPA) e fibrinogênio, por imuno-turbidimetria. A taxa de excreção de albumina (EUA) foi determinada por RIE, em amostra de urina de 10h, definindo-se normoalbuminúria como duas taxas de EUA <20µg/min. Pacientes com DM1 foram avaliados quanto à presença de retinopatia por oftalmoscopia indireta. No DM1 os níveis de PCR [0,23 (0,01-2,90) vs. 0,14 (0,01-2,41) mg/dl, p= 0,0172& e de alfa1-GPA [53,5 (37-115) vs. 40 (19-78) mg/dl, p< 0,0001& foram maiores quando comparados aos sem DM. Não houve diferença em relação ao fibrinogênio. Na regressão linear múltipla em stepwise, tendo a a1-GPA como variável dependente, as variáveis independentes associadas e preditoras foram a HbA1c (r²= 0,26; p< 0,05) e a glicemia (r²= 0,26; p< 0,05); tendo a PCR e o fibrinogênio como variáveis dependentes, nenhuma variável independente foi significativa. Na correlação de Pearson, a PCR correlacionou-se com HbA1c (r= 0,18; p= 0,05). Concluímos que a PCR e alfa1-GPA estão aumentadas no DM1, independente da presença da microalbuminúria, retinopatia e doença macrovascular clínica. Estudo prospectivo será necessário para estabelecermos o valor preditivo destes marcadores na evolução para complicações crônicas micro e macrovasculares.

Effect of Retama raetam on lipid metabolism in normal and recent-onset diabetic rats

The purpose of this study was to examine the effect of single and repeated oral administration of the aqueous extract of Retama raetam (Forssk) Webb (RR) (20 mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of RR induced a significant decrease of the plasma triglycerides concentrations one week after repeated oral administration (P<0.05). This reduction was maintained two weeks after once daily repeated oral administration (P<0.05). A significant decrease of plasma cholesterol levels was also observed one week (P<0.05) and two weeks (0.05) after repeated oral administration. In diabetic rats, RR treatment caused a significant decrease of plasma triglycerides levels after a single (P<0.05) and repeated (P<0.001) oral administration. A significant decrease of cholesterol levels was observed four hours after a single oral administration of the RR aqueous extract (P<0.05). One week after repeated oral administration of RR aqueous extract, the plasma cholesterol levels were significantly decreased (P<0.05) and still dropped after two weeks (P<0.005). On the other hand, the repeated oral administration of RR aqueous extract caused a significant decrease of body weight one week after repeated oral treatment in diabetic rats (P<0.05). We conclude that the aqueous extract of RR exhibits lipid and body weight lowering activities in both normal and severe hyperglycemic rats after repeated oral administration of RR aqueous extract at a dose of 20 mg/kg.

Effects of an aqueous extract of Triticum repens on lipid metabolism in normal and recent-onset diabetic rats

The aim of this study was to demonstrate the effects of single and repeated oral administration of the aqueous rhizomes extract of Triticum repens (TR) (20 mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of TR induced a significant decrease in the plasma triglycerides concentrations 4 days (P<0.05) and 1 week after repeated oral administration (P<0.05). This reduction was abolished 2 weeks after once daily repeated oral administration. A significant decrease of plasma cholesterol levels was observed only 1 week (P<0.05) after repeated oral administration. In diabetic rats, TR treatment caused a significant decrease in plasma triglycerides levels after a single (P<0.01) and repeated (P<0.001) oral administration. A strong decrease in cholesterol level was observed 6 h after a single oral administration of the aqueous extract TR (P<0.001). Four days after repeated oral administration of TR aqueous extract, the plasma cholesterol level was significantly decreased (P<0.05) and still dropped after 2 weeks (P<0.001). On other hand, the repeated oral administration of aqueous TR extract caused a significant decrease in body weight 2 weeks after repeated oral treatment in diabetic rats (P<0.05). We conclude that the aqueous extract of TR exhibits lipid and body weight lowering activities in severe hyperglycaemic rats after repeated oral administration of aqueous TR extract at a dose of 20 mg/kg.

Cholesterol-lowering activity of the aqueous extract of Spergularia purpurea in normal and recent-onset diabetic rats

The purpose of this study was to examine the effect of single and repeated oral administration of the aqueous extract of Spergularia purpurea (SP) at a dose of 10mg/kg in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of SP induced a significant decrease of the plasma cholesterol concentrations 6h after a single oral administration (P<0.05) and 2 weeks after repeated oral administration (P<0.05). The plasma triglycerides levels increased significantly 6h after a single oral administration (P<0.05) and decreased 2 weeks after repeated oral administration (P<0.05). In diabetic rats, SP treatment caused a significant decrease of plasma cholesterol levels after a single (P<0.01) and repeated (P<0.01) oral administration. A significant increase of triglycerides levels was observed 6h after a single oral administration of the SP aqueous extract (P<0.01). One week after repeated oral administration of SP aqueous extract, the plasma triglycerides levels were significantly decreased (P<0.005) and still dropped after 2 weeks (P<0.01). On the other hand, the repeated oral administration of SP aqueous extract caused a significant decrease of body weight after 2 weeks of treatment in both normal (P<0.001) and diabetic (P<0.01) rats. We conclude that the aqueous extract of SP exhibits a cholesterol and body weight-lowering activities in both normal and severe hyperglycaemic rats.

Lipoprotein subclass measurements by nuclear magnetic resonance spectroscopy improve the prediction of coronary artery disease in Type 1 diabetes. A prospective report from the Pittsburgh Epidemiology of Diabetes Complications Study

AIM/HYPOTHESIS

To examine whether nuclear magnetic resonance lipoprotein spectroscopy improves the prediction of coronary artery disease in patients with Type 1 diabetes, independently of conventional lipid and other risk factors.

METHODS

A prospective nested case-control design of subjects with childhood onset Type 1 diabetes from the Pittsburgh Epidemiology of Diabetes Complications Study was used. 59 controls were age-, sex- and duration-matched to 59 incident cases of coronary artery disease (fatal or non-fatal myocardial infarction, angina, coronary stenosis >50%) occurring during 10 years of follow-up. Lipid mass and particle concentrations of VLDL, LDL, and HDL subclasses, grouped into three size categories (large, medium, and small), were assessed prior to event with nuclear magnetic resonance spectroscopy.

RESULTS

Univariate analyses showed that both lipid mass and particle concentrations of all three VLDL subclasses, small LDL, medium LDL, and medium HDL were increased in CAD cases compared to controls, while large HDL was decreased. Mean LDL and HDL particle sizes were lower in cases. In multivariate models using conventional lipid and non-lipid risk factors, triglycerides and overt nephropathy were the strongest predictors of CAD. Nuclear magnetic resonance measures further improved the prediction, i.e. large HDL particle concentration (OR=0.43, p=0.030), medium HDL mass (OR=3.79, p=0.026) and total VLDL particle concentration (OR=2.33, p=0.033).

CONCLUSION/INTERPRETATION

While these results underscore the importance of triglycerides and overt nephropathy in CAD risk in Type 1 diabetic patients, they also suggest that nuclear magnetic resonance lipoprotein spectroscopy could further refine its prediction and show novel findings concerning HDL subclasses.

Fibrinogen is a marker for nephropathy and peripheral vascular disease in type 1 diabetes: studies of plasma fibrinogen and fibrinogen gene polymorphism in the DCCT/EDIC cohort

We examined whether plasma fibrinogen levels and the beta-fibrinogen gene G(-455)-->A polymorphism were related to microvascular or macrovascular disease in patients (n = 909) with type 1 diabetes enrolled in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/ EDIC). Univariate regression showed that fibrinogen levels were correlated with BMI (r = 0.15; P < 0.0001), HbA(1c) (r = 0.11; P = 0.0014), total cholesterol (r = 0.17; P < 0.0001), and LDL cholesterol (r = 0.16; P < 0.0001) in all patients. In men, but not women, waist-to-hip ratio (r = 0.20; P < 0.0001) and triglycerides (r = 0.13; P = 0.0047) also became powerful predictors of fibrinogen level; in women, but not men, fibrinogen was correlated with both diastolic (r = 0.16; P = 0.0011) and systolic (r = 0.11; P = 0.0241) blood pressure. Fibrinogen was correlated with urinary albumin excretion rates in men (r = 0.13; P = 0.0033), but not in women. In both sexes, however, the development of proteinuria (albumin excretion >300 mg/24 h) was accompanied by 1.5-fold increment in plasma fibrinogen compared with patients with normal excretion or microalbuminuria. In addition, high fibrinogen levels were associated with a lower average ankle-brachial index in women (r = -0.13; P = 0.0075), but not men. Multiple regression analyses demonstrated that plasma fibrinogen was independently correlated with high albumin excretion rate in men, and with low average ankle-brachial index in women. Fibrinogen was not correlated with the severity of retinopathy. Carotid artery intima-medial thickness was not correlated with fibrinogen, and the G(-455)-->A polymorphism in the 5' promoter region of the beta-fibrinogen gene did not influence circulating fibrinogen levels. However, the presence of the more common G(-455) allele was associated with greater intima-medial thickness in the internal carotid artery (ANCOVA P = 0.045). Last, hyperfibrinogenemia in type 1 diabetes is associated with components of the insulin resistance syndrome trait cluster, and the association is influenced by sex.

ACE inhibitor intervention in Type 1 diabetes with low grade microalbuminuria

Several clinical trials have consistently shown that antihypertensive treatment, particularly with angiotensin-converting enzyme inhibitors (ACE-I) reduces albuminuria in Type 1 diabetic patients. More recently, data on the beneficial effects of ACE-I on the preservation of glomerular filtration rate and renal ultrastructure have emerged. However, in general, these trials have recruited a wide spectrum of diabetics, including some patients with severe albuminuria. Thus, the question of the ideal stage at which to instigate what is likely to be lifelong therapy in young people still remains unanswered. Exercise is known to significantly increase both blood pressure (BP) and urinary albumin excretion (UAE), both of which are important determinants of progression of nephropathy in diabetes. Thus, it is possible that exercise may have an adverse effect on diabetic renal disease. The effects of ACE-I on exercise-BP and exercise-UAE in microalbuminuric Type 1 diabetic patients has not been examined in long-term placebo-controlled studies. In the second part of this two-part review, we examine the effects of the ACE-I, lisinopril, 20 mg o.d. for two years, in comparison with placebo, on UAE, 24-hour ambulatory BP, exercise-BP, exercise-UAE and renal haemodynamics in 22 patients with Type 1 diabetes and low-grade microalbuminuria. We further discuss the effects of ACE-I on nephropathy and other complications of diabetes.

Diabetes mellitus and coronary artery disease: therapeutic considerations

Diabetes mellitus affects about 6% of the U.S. population and represents a significant public health challenge, with numbers of those affected increasing every year. The most common cause of death in these patients is macrovascular disease, with coronary disease being the predominant form. The pathophysiology of coronary disease in patients with diabetes is complex and involves elements of hyperglycemia, dyslipidemia, hyperinsulinemia, as well as a procoagulant vascular milieu. First-generation trials looking at revascularization of multivessel disease in patients with diabetes have had long clinical follow-up periods and seem to consistently favor coronary bypass grafting over percutaneous interventions; however, newer trials that include the use of stents and glycoprotein IIb/IIIa inhibitor therapy as part of the latter strategy have raised some interesting questions, so that the issue remains controversial and by no means settled.

Benefícios da atividade física no perfil lipídico de pacientes com diabetes tipo 1

Avaliamos a resposta do perfil lipídico a uma intervenção não-farmacológica de curta duração, e investigamos se alterações nas lipoproteínas estavam presentes, antes da nefropatia diabética (ND) clínica, em 46 pacientes jovens com diabetes tipo 1 (DM1), com idade de 15,5±1,5 anos submetidos a um programa de 8 dias de dieta apropriada e exercícios, durante controle glicêmico estável (glicemia média 110,3±27,1mg/dl e HbA1c 6,9±1,3%). No início, 65% dos jovens apresentavam colesterol total > 160mg/dl (IC 95% 0,51-0,78), enquanto que ao final somente 38% (IC 95% 0,24-0,51) tinham tais níveis. A melhora no perfil lipídico foi ainda melhor para a fração LDL, considerando que inicialmente 67% mostravam valores acima de 100mg/dl (IC 95% 0,55-0,78) e 24% (IC 95% 0,12-0,36) ao final. Valores de HDL-colesterol subnormais (< 40mg/dl) ocorreram em 38% (95% IC 0,24-0,51) e 11% (IC 95% 0,02-0,20) deles, no início e final do período. A razão albumina/creatinina média foi 9,0±8,0mg/g de creatinina. Encontramos fracas correlações entre a razão albumina/creatinina e os níveis de colesterol total (r= 0,21), LDL (r= 0,24), VLDL (r= 0,30), HDL (r= -0,17) e de triglicérides (r= 0,31). Dentro da faixa de referência de albuminúria, não foi encontrada nenhuma associação entre a excreção urinária de albumina e os níveis de lípides nos pacientes com DM1 estável. Um programa de exercícios regulares é eficaz em otimizar o perfil lipídico nestes pacientes, independentemente do controle glicêmico. Nossos dados não apoiam a hipótese de que mudanças no metabolismo lipídico precederiam a microalbuminúria no curso da ND.

Blood pressure and cardiac autonomic function in relation to risk factors and treatment perspectives in Type 1 diabetes

The cumulative incidence of diabetic nephropathy in Type 1 diabetes mellitus is in the order of 25 30%. The recognition that elevated blood pressure (BP) is a major factor in the progression of these patients to end-stage renal failure has led to the widespread use of antihypertensive therapy in order to preserve glomerular filtration rate and ultimately to reduce mortality. The routine measurement of microalbuminuria allows early identification of the subgroup of patients at increased risk of developing clinical nephropathy. Microalbuminuric Type 1 diabetic patients show a number of characteristic pathological abnormalities. In addition to elevated BP and abnormal circadian rhythm, there are also associated abnormalities of vagal function, lipid profile and endothelial function, as well as an increased prevalence of retinopathy. The first section of this two-part review focusses on the early changes associated with renal involvement in Type 1 diabetes. It addresses the associations between urinary albumin excretion, glycaemic control, smoking, BP, circadian BP variation, QT interval abnormalities and autonomic function in three groups of patients; those with normoalbuminuria, those progressing towards microalbuminuria and those with established low-grade microalbuminuria.

Comparison of a homogeneous assay with a precipitation method for the measurement of HDL cholesterol in diabetic patients

OBJECTIVE

To compare direct-measured HDL cholesterol with HDL cholesterol measured by a precipitation method.

RESEARCH DESIGN AND METHODS

We compared a homogeneous assay for direct HDL cholesterol analysis with the phosphotungstic acid magnesium chloride precipitation method in 55 type 1 diabetic patients, 70 type 2 diabetic patients, and 82 nondiabetic normal control subjects with plasma triglyceride levels <4.6 mmol/l. The cholesterol content of HDL determined by the direct assay was overall 0.1 mmol/l higher in all three groups than HDL cholesterol measured after precipitation, but the two methods were closely correlated (r(2) = 0.98, P < 0.001).

RESULTS

HbA(1c), blood glucose, serum albumin, serum bilirubin, or triglyceride did not influence the differences of the two HDL cholesterol measurements. Because we have previously shown HDL cholesterol isolated by phosphotungstic acid precipitation to be lower than that by ultracentrifugation, the positive bias found in this study was expected. It seems that the direct HDL cholesterol assay reacts with apolipoprotein (apo) B-containing lipoproteins in the fraction with a density of >1.063; these apo B-containing lipoproteins are suggested to be coprecipitated with the phosphotungstic acid method. We also measured LDL cholesterol directly by a LDL cholesterol plus method and found no significant differences between this method and LDL cholesterol calculated from Friedewald's formula.

CONCLUSIONS

Direct homogeneous assay for HDL cholesterol determination in diabetic patients seems not to exhibit a negative bias, in contrast to the precipitation method, when compared with the ultracentrifugation method. In addition, the direct assay saves time and is not influenced by type of diabetes or degree of metabolic control.

Renal handling of albumin: a critical review of basic concepts and perspective

Biochemical and physiological processes that underlie the mechanism of albuminuria are completely reassessed in this article in view of recent discoveries that filtered proteins undergo rapid degradation during renal passage and the resulting excreted peptide fragments are not detected by conventional urine protein assays. This means that filtered protein and/or albumin levels in urine have been seriously underestimated. The concept that albuminuria is a result of changes in glomerular permeability is questioned in light of these findings and also in terms of a critical examination of charge selectivity, shunts, or large-pore formation and hemodynamic effects. The glomerulus appears to function merely in terms of size selectivity alone, and for albumin, this does not change significantly in disease states. Intensive albumin processing by a living kidney occurs through cellular processes distal to the glomerular basement membrane. Failure of this cellular processing primarily leads to albuminuria. This review brings together recent data about urinary albumin clearance and current knowledge of receptors known to process albumin in both health and disease states. We conclude with a discussion of topical and controversial issues associated with the proposed new understanding of renal handling of albumin.

Abnormalities of glucose metabolism in patients with early renal failure

Abnormalities of glucose metabolism and hyperinsulinemia have been demonstrated in patients with end-stage renal disease and may contribute to the development of atherosclerotic complications in these patients. In the present study, we investigated the stage of renal failure in which abnormalities of glucose metabolism develop and whether these abnormalities were associated with an increased prevalence of cardiovascular events in patients with early renal failure. In 321 untreated essential hypertensive patients, we assessed renal function by measuring 24-h creatinine clearance, urinary protein excretion, and microalbuminuria; we assessed cardiovascular status by clinical and laboratory tests; and we measured plasma glucose, insulin, and C-peptide levels at fasting and after a 75-g oral glucose load. To evaluate insulin sensitivity, a hyperinsulinemic-euglycemic clamp was performed in a subgroup of 104 patients. Patients with creatinine clearance < 30 ml.min(-1).1.73 m(-2), severe hypertension, BMI < 30 kg/m(2), and diabetes or family history of diabetes were excluded. Hypertensive patients were found to be hyperinsulinemic when compared with 92 matched normotensive subjects. Early renal failure (creatinine clearance < 90 ml.min(-1).1.73 m(-2)) caused by hypertensive nephrosclerosis was detected in 116 of 321 patients. Analysis of patients with varying degrees of renal function impairment demonstrated increased plasma glucose and insulin response to oral glucose load, decreased fasting glucose-to-insulin ratio, and reduced sensitivity to insulin only in those patients with creatinine clearance < 50 ml.min(-1).1.73 m(-2). Parameters of glucose metabolism were not correlated with creatinine clearance and microalbuminuria. Prevalence of atherosclerotic cardiovascular events was significantly related to reduction of creatinine clearance, but parameters of glucose metabolism were comparable in patients with and without evidence of atherosclerotic damage. Thus, in patients with hypertensive nephrosclerosis and early impairment of glomerular filtration, alterations of glucose metabolism become evident only when creatinine clearance is < 50 ml.min(-1).1.73 m(-2) and are not related to microalbuminuria and cardiovascular complications.

Endothelial dysfunction in children with type 1 diabetes mellitus

Endothelial dysfunction is defined as the loss of endothelium properties, e.g. alteration of protein synthesis, increased vascular tone and permeability, acquisition of prothrombotic and antifibrinolytic properties. Endothelium, a primary target of unbalanced glycaemic control, is involved in the pathogenesis of vascular complications in patients with type 1 diabetes mellitus (DM). Vascular endothelium damage is characterised by an increase of endothelium-derived regulatory proteins. vWF and t-PA may be useful to investigate early endothelium involvement. However, impaired endothelium-dependent vasodilatation may be a more sensitive marker. Abnormal markers of endothelial cell activation and impaired endothelium-dependent vasodilatation have been observed in young patients with type I DM. Hyperglycaemia may alter normal endothelium functions, either directly or indirectly, by inducing different metabolic pathways. Complete understanding of the pathophysiology of endothelial dysfunction may lead to timely therapeutic intervention to prevent its development and to slow the progression of diabetic complications.

Differing associations of lipid and lipoprotein disturbances with the macrovascular and microvascular complications of type 1 diabetes

OBJECTIVE

Cardiovascular disease (CVD) is increased in patients with type 1 diabetes, but lipid and lipoprotein patterns remain favorable. In contrast, nephropathy is associated with an adverse distribution. We compared the associations and predictive power of lipid and lipoprotein disturbances with these complications.

RESEARCH DESIGN AND METHODS

A nested case-control study from the EURODIAB cohort of 140 case subjects with evidence of at least one complication and 84 control subjects with no complications were analyzed. Conventional and unconventional lipid and lipoprotein fractions, including apolipoprotein (apo)-A1, lipoprotein (Lp)-A1, LpA1/A2, apoB, and LDL particle size were measured centrally.

RESULTS

CVD was only associated with increased LDL cholesterol (3.6 vs. 3.0 mmol/l, P = 0.02). In contrast, albuminuria was associated with elevated cholesterol, triglyceride, LDL, and apoB and with diminished LDL particle size. No disturbances in HDL and related lipoproteins were noted. In normoalbuminuric patients, CVD was not associated with any significant changes in lipids. CVD in macroalbuminuric patients was associated with increased triglyceride level (2.37 vs. 1.07 mmol/l, P = 0.001; P = 0.02 for CVD/albuminuria interaction) and LDL cholesterol (5.4 vs. 3.3 mmol/l, P = 0.005; P = 0.004 for interaction). Independent associations were observed for total cholesterol and for LDL particle size and albuminuria.

CONCLUSIONS

Abnormalities in lipid and lipoprotein disturbances are more closely related to albuminuria than to CVD in patients with type 1 diabetes. Measurement of conventional parameters provide sufficient risk information. ApoB and LDL particle size offer limited extra information. HDL metabolism remains undisturbed in the presence of complications. These changes reflect associations with glycemic control, which is the key to understanding lipid and lipoprotein disturbances.

Microalbuminuria in type 1 diabetes: rates, risk factors and glycemic threshold

BACKGROUND

The occurrence of microalbuminuria in type 1 diabetes is strongly predictive of renal and cardiovascular disease and is still likely to occur despite improvements in glycemic control. A better understanding of microalbuminuria is required to inform new interventions. We determined the incidence and risk factors for microalbuminuria [albumin excretion rate (AER) 20 to 200 microg/min] in the EURODIAB Prospective Complications Study.

METHODS

This is a seven-year follow-up (between 1988 and 1991) of 1134 normoalbuminuric men and women (aged 15 to 60) with type 1 diabetes from 31 European centers. Risk factors and AER were measured centrally.

RESULTS

The incidence of microalbuminuria was 12.6% over 7.3 years. Independent baseline risk factors were HbA1c (7.1 vs. 6.2%, P = 0.0001) and AER (9.6 vs. 7.8 microg/min, P = 0.0001) and, independent of these, fasting triglyceride (0.99 vs. 0.88 mmol/L, P = 0.01), low-density lipoprotein cholesterol (3.5 vs. 3.2 mmol/L, P = 0.02), body mass index (24.0 vs. 23.4 kg/m2, P = 0.01), and waist to hip ratio (WHR; 0.85 vs. 0.83, P = 0.009). Triglyceride and WHR risk factors were nearly as strong as AER in predicting microalbuminuria (standardized regression effects of 1.3 for triglyceride and WHR and 1.5 for AER). Blood pressure at follow-up, but not at baseline, was also raised in those who progressed. There was no evidence of a threshold of HbA1c on microalbuminuria risk.

CONCLUSIONS

The incidence of microalbuminuria in patients with type 1 diabetes remains high, and there is no apparent glycemic threshold for it. Markers of insulin resistance, such as triglyceride and WHR, are strong risk factors. Systemic blood pressure is not raised prior to the onset of microalbuminuria.

Microalbuminuria and markers of the atherosclerotic process: the D.E. S.I.R. study

The relationship between microalbuminuria and tissue-type plasminogen activator antigen (tPA-ag) and fibrinogen was evaluated in non-diabetic subjects. Subjects were participants of the D.E.S.I. R. (Data from an Epidemiological Study on the Insulin Resistance syndrome) Study. Analyses were carried out on 2248 women and 2402 men for fibrinogen and on 272 women and 284 men for tPA-ag. Microalbuminuria was defined as urinary albumin concentration greater than 20 mg/l. Men with microalbuminuria had a 6% higher fibrinogen concentration than those without (3.07 g/l (95% confidence interval: 2.99,3.15) vs. 2.89 g/l (2.87,2.91), adjusted for age and smoking). This relationship existed in hypertensive as well as non-hypertensive subjects. The association between microalbuminuria and tPA-ag existed only in hypertensive men, those with microalbuminuria having a 21% higher tPA-ag than those without (4.39 ng/ml (3.70,5.08) vs. 3.63 ng/ml (3.32,3.94), adjusted for age and smoking). Adjustment for other risk markers for cardiovascular disease did not change the results. There was no relationship between microalbuminuria and these haemostatic factors in women. The results of this study suggest that in non-diabetic men, microalbuminuria is associated with fibrinogen, but with tPA-ag only when concomitant with hypertension.

Plasma lipids and urinary albumin excretion rate in Type 1 diabetes mellitus: the EURODIAB IDDM Complications Study

AIMS

To examine the relationship between increased urinary albumin excretion rate and fasting plasma lipids among male and female respondents to the EURODIAB IDDM Complications Study, and attempt to explain inconsistencies in previous reports.

METHODS

A cross-sectional study of 3250 randomly selected Type 1 diabetic patients from 31 diabetes clinics in 16 European countries was carried out between 1989 and 1990. Plasma lipids and urinary albumin were measured centrally. The present analysis was confined to the subgroup of 2205 patients attending after a 10-12 h overnight fast. Mean age was 33 years (SD 10) and mean duration of Type 1 diabetes mellitus was 15 years (SD 9).

RESULTS

The prevalence of microalbuminuria (24-h urinary albumin excretion rate 20-200 microg/min) was 21.7% (95% confidence interval 19.9-23.5) and macroalbuminuria (24-h urinary albumin excretion rate > 200 microg/min) 7.8% (6.6-9.0). In comparison to patients with normal urinary albumin excretion rate (< 20 microg/min), and after controlling for age, sex, glycaemic control, duration of diabetes and current smoking, macroalbuminuria was associated with significantly (P<0.01) increased fasting plasma triglycerides, cholesterol, LDL-cholesterol, cholesterol:HDL-cholesterol ratio and, in women, reduced HDL-cholesterol. In men and women with microalbuminuria, the only significant association was with increased plasma triglycerides.

CONCLUSIONS

These data confirm that there is an association between fasting plasma lipids and increasing urinary albumin excretion rate in European Type 1 diabetic patients. In microalbuminuric patients, however, the association was weaker than previously reported and partly explained by confounding factors.

Diabetes, hemoglobin A(1c), cholesterol, and the risk of moderate chronic renal insufficiency in an ambulatory population

Moderate chronic renal insufficiency is common, with 12.5 million individuals in the United States estimated to have a creatinine clearance less than 50 mL/min/1.73 m(2). Little is known about the risk factors for moderate chronic renal insufficiency. We studied 1, 428 subjects with Cockcroft-Gault-estimated creatinine clearances greater than 70 mL/min in a hospital-based ambulatory population. Over a mean of 5.7 +/- 1.3 years, 86 subjects developed moderate chronic renal insufficiency, defined as a decrease in creatinine clearance to less than 60 mL/min (1.1 case/100 person-years). Risk factors for moderate chronic renal insufficiency were identified using a proportional hazards model controlling for age, sex, race, systolic blood pressure, and angiotensin-converting enzyme (ACE) inhibitor use. The risk for developing moderate chronic renal insufficiency was associated with diabetes mellitus (relative risk, 2.1; 95% confidence interval [CI], 1.3 to 3.3) and elevated hemoglobin A(1c) levels. Compared with subjects with normoglycemia (hemoglobin A(1c) </= 5.7%), the relative risk for moderate chronic renal insufficiency for patients in the upper quartile of hemoglobin A(1c) (>9.0%) was 2.7 (95% CI, 1.4 to 5.1). The development of moderate chronic renal insufficiency was also independently predicted by elevated maximum serum cholesterol level. Compared with subjects with maximum cholesterol levels of 250 mg/dL or less, the relative risk for those with maximum cholesterol levels greater than 350 mg/dL was 2.4 (95% CI, 1.1 to 5.2). Similar relative risks were obtained when moderate chronic renal insufficiency was defined by the development of an increase in serum creatinine level. Hypercholesterolemia was also associated with moderate chronic renal insufficiency among persons without diabetes. In conclusion, the risk for developing moderate chronic renal insufficiency is increased by diabetes and elevated hemoglobin A(1c) and serum cholesterol levels. Modification of these risk factors may decrease the incidence of moderate chronic renal insufficiency.

Lipoprotein(a) and apolipoprotein(a) isoforms and proteinuria in patients with moderate renal failure

BACKGROUND

Atherosclerotic diseases are a major cause of death in patients with renal failure. Increased serum concentrations of lipoprotein(a) [Lp(a)] have been established as a genetically controlled risk factor for these diseases and have been demonstrated in patients with moderate renal failure, suggesting that this lipoprotein contributes to the increased cardiovascular risk seen in these patients. Variable alleles at the apolipoprotein(a) [apo(a)] gene locus are the main determinants of the serum Lp(a) level in the general population. The purpose of this study was to investigate apo(a) isoforms in patients with moderate renal failure and mild proteinuria (less than 1.0 g/day).

METHODS

In 250 consecutive subjects recruited at a hypertension clinic, we assessed the renal function by 24-hour creatinine clearance, proteinuria, and microalbuminuria, as well as the prevalence of atherosclerotic disease, and we also measured apo(a) isoforms, serum albumin, and Lp(a) concentrations.

RESULTS

Moderate impairment of renal function (creatinine clearance, 30 to 89 ml/min per 1.73 m2 of body surface area) was found in 97 patients. Lp(a) levels were significantly greater in patients with moderate renal failure (21.7+/-23.9 mg/dl) as compared with patients with normal renal function (15.6+/-16.4 mg/dl, P<0.001), and an inverse correlation was observed between log Lp(a) and creatinine clearance (r = -0.181, P <0.01). However, no difference was found in the frequency of low molecular weight apo(a) isoforms between patients with normal (25.5%) and impaired (27.8%) renal function. Only patients with the smallest size apo(a) isoforms exhibited significantly elevated levels of Lp(a), whereas the large-size isoforms had similar concentrations in patients with normal and impaired renal function. No significant relationship was found between serum Lp(a) and proteinuria. Clinical and laboratory evidence of one or more events attributed to atherosclerosis was found in 9.8% of patients with normal renal function and 25.8% of patients with moderate renal failure (P<0.001).

CONCLUSIONS

These results indicate that renal failure per se or other genes beside the apo(a) gene locus are responsible for the elevation of serum Lp(a) levels in patients with moderate impairment of renal function. The elevation of Lp(a) levels occurs independently of the level of proteinuria and may contribute to the risk for atherosclerotic disease in these patients.