n(6)-(1-carboxyethyl)lysine and Diabetes-Mellitus--Type-2

In vitro and animal experiments have shown inhibiting effects of angiotensin receptor blockers (ARBs) on the formation of advanced glycation end products (AGEs), which are known to be involved in the development of cardiovascular complications in diabetes. However, sufficient human data to confirm such beneficial effects of ARBs on AGEs are lacking. Therefore, we investigated the effects of irbesartan treatment on plasma levels of the AGEs N(ε)(1-carboxymethyl)lysine (CML) and N(ε)(1-carboxyethyl)lysine (CEL) in hypertensive patients with type 2 diabetes and microalbuminuria.. We analysed data from a multicentre, double-blind, parallel, randomized controlled trial in patients with type 2 diabetes and microalbuminuria, the primary goal of which was to examine the renoprotective effects of irbesartan treatment (150 or 300 mg daily). Secondary end points included plasma CML and CEL in the treatment arm receiving 300 mg irbesartan (n = 139) and in the placebo group (n = 125). Effects of treatment at 1- and 2-year follow-up were analysed by means of generalized estimating equations according to an intention-to-treat principle.. Levels of CML and CEL did not differ between groups at baseline. No significant changes were observed in CML and CEL over time in either group and there was no effect of treatment on CML and CEL at any time-point. Mean differences for the irbesartan versus placebo group over time were -0.96 μmol/mol lysine (95% confidence interval: -3.43 to 1.51) for CML and -0.10 μmol/mol lysine (-0.76 to 0.56) for CEL.. Long-term irbesartan treatment does not influence plasma levels of the AGE CML and CEL in patients with type 2 diabetes and microalbuminuria.

Topics: Adult; Aged; Albuminuria; Angiotensin Receptor Antagonists; Biomarkers; Biphenyl Compounds; Diabetes Complications; Diabetes Mellitus, Type 2; Double-Blind Method; Female; Glycation End Products, Advanced; Humans; Hypertension; Irbesartan; Lysine; Male; Middle Aged; Prognosis; Tetrazoles

Experimental and histological data suggest a role for advanced glycation end products (AGEs) in cardiovascular disease (CVD), particularly in type 2 diabetes (T2DM). However, the epidemiological evidence of an adverse association between AGEs and CVD remains inconclusive. We therefore investigated, in individuals with various degrees of glucose metabolism, the associations of plasma AGEs with prevalent CVD.. We measured plasma levels of protein-bound N(ε)-(carboxymethyl)lysine (CML), N(ε)-(carboxyethyl)lysine (CEL), and pentosidine, in participants from two Dutch cohort studies (n = 1291, mean age 64.7 ± 8.3 years, 45% women), including 573 individuals with normal glucose metabolism, 304 with impaired glucose metabolism, and 414 with T2DM. In addition, we measured free CML, CEL, and 5-hydro-5-methylimidazolone in a subset of participants (n = 554). Data were analyzed with multiple logistic or linear regression analyses.. CEL (32 [interquartile range: 25-40] vs 28 [22-35] nmol/mmol lysine) and pentosidine (0.53 [0.43-0.67] vs 0.48 [0.40-0.59] nmol/mmol lysine) as well as free CEL (48 [39-62] vs 45 [36-56] nmol/L) and 5-hydro-5-methylimidazolone (141 [96-209] vs 116 [84-165] nmol/L) were higher in individuals with vs without CVD, whereas protein-bound CML was lower (33 [27-38] vs 34 [29-39] nmol/mmol lysine). However, these differences disappeared after adjustment for confounders. The associations did not differ consistently between individuals with and without T2DM.. We found no independent adverse associations of plasma AGEs with CVD in individuals with normal glucose metabolism, impaired glucose metabolism, and T2DM.

Topics: Aged; Arginine; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Female; Glucose; Humans; Lysine; Male; Middle Aged

Advanced glycation end products (AGEs) play a pivotal role in loss of lens transparency, i.e., cataract. AGEs formation occurs as a result of sequential glycation and oxidation reaction between reducing sugars and protein. AGEs production takes place throughout the normal aging process but its accumulation is found to be more rapid in diabetic patients. In this study, we quantified AGEs and N-(carboxyethyl) lysine (CEL) in human cataractous lenses from non-diabetic (n=50) and diabetic patients (n=50) using ELISA. We observed significantly higher (p<0.001) levels of lens AGEs and CEL in diabetic patients with cataract as compared with their respective controls. The presence of AGEs and CEL was also determined by western blotting and immuno-histochemical analysis. Furthermore, isolated β-crystallin from cataractous lenses of non-diabetic and diabetic patients was incubated with different sugars to evaluate the extent of glycation in a time dependent manner. Our data indicated more pronounced glycation in patients suffering from diabetes as compared to non-diabetics subjects demonstrating the need to focus on developing normoglycemic approaches. Such studies may provide an insight in developing therapeutic strategies and may have clinical implications.

Topics: Aged; beta-Crystallins; Cataract; Diabetes Mellitus, Type 2; Female; Glycation End Products, Advanced; Humans; Immunohistochemistry; Lens, Crystalline; Lysine; Male; Middle Aged

Diabetic retinopathy is a frequent microvascular complication. In search of novel risk markers, we analysed the association between serum levels of the major advanced glycation end product N(epsilon)-carboxymethyl-lysine (CML) and prevalence of advanced stages of retinopathy in Type 2 diabetic patients without nephropathy.. We carried out a case-control study of Type 2 diabetic patients with and without advanced stages of diabetic retinopathy. Retinopathy and macular oedema were defined according to standard criteria. Serum levels of CML were estimated by means of a novel competition-based ELISA assay.. Serum levels of CML were significantly different between age-matched controls (n=792; mean value +/- SD: 521+/-134 ng/ml), Type 2 diabetic patients without severe retinopathy (821+/-141 ng/ml; p<0.0001) and Type 2 diabetic patients with proliferative retinopathy (1182+/-346 ng/ml; p<0.0001). Levels of CML greater than 1000 ng/ml represented a 25-fold increase in risk of proliferative retinopathy. Receiver operating characteristics analysis revealed a CML threshold of 1087 ng/ml (100% sensitivity, 93% specificity) for clinically significant macular oedema.. High serum levels of CML were associated with advanced stages of retinopathy. Serum levels were shown to be a progressive risk marker, whereby a level of more than 1000 ng/ml induced a 25-fold increase in risk of proliferative retinopathy and clinically significant macular oedema. Our data suggest that serum levels of CML provide a novel risk marker for advanced stages of diabetic retinopathy in Type 2 diabetic patients.

Topics: Biomarkers; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Female; Glycation End Products, Advanced; Humans; Hypoglycemic Agents; Lysine; Macular Degeneration; Male; Middle Aged