HbA1c and serum levels of advanced glycation and oxidation protein products in poorly and well controlled children and adolescents with type 1 diabetes mellitus

Eight Weeks of Intermittent Exercise in Hypoxia, with or without a Low-Carbohydrate Diet, Improves Bone Mass and Functional and Physiological Capacity in Older Adults with Type 2 Diabetes

In an increasingly aging and overweight population, osteoporosis and type 2 diabetes (T2DM) are major public health concerns. T2DM patients experience prejudicial effects on their bone health, affecting their physical capacity. Exercise in hypoxia (EH) and a low-carbohydrate diet (LCD) have been suggested for therapeutic benefits in T2DM, improving bone mineral content (BMC) and glycemic control. This study investigated the effects of EH combined with an LCD on body composition and functional and physiologic capacity in T2DM patients. Older T2DM patients (n = 42) were randomly assigned to the following groups: (1) control group: control diet + exercise in normoxia; (2) EH group: control diet + EH; (3) intervention group: LCD + EH. Cardiopulmonary tests (BRUCE protocol), body composition (DEXA), and functional capacity (6MWT, handgrip strength) were evaluated. Body mass index (kg/m2) and body fat (%) decreased in all groups (p < 0.001). BMC (kg) increased in all groups (p < 0.001) and was significantly higher in the EH and EH + LCD groups (p < 0.001). VO2peak improved in all groups (p < 0.001), but more so in the hypoxia groups (p = 0.019). Functional capacity was increased in all groups (p < 0.001), but more so in the EH group in 6MWT (p = 0.030). EH with and without an LCD is a therapeutic strategy for improving bone mass in T2DM, which is associated with cardiorespiratory and functional improvements.

Potential impact of auxin in modulation of insulin resistance in diabetic rats

The rational of this study to find out the impact of auxins in prevention of diabetic complications in rats. Seventy-five rats were randomly grouped into five groups: Group I; control (n = 15). (Groups 2-5, 60 rats) were received a single dose of STZ i.p, at dose of 65 mg/kg for induction diabetes. Group II; diabetic untreated. Group III; Rats were given auxin subcutaneous (2.5 µg/kg b.w). Group IV; rats were given auxin (5 µg/kg b.w). Group V; rats were injected insulin (5 units/kg b.w/day) as positive control. Treatment of diabetic rats with auxin (2.5 or 5 ug/kg b.w) for 8 weeks reversed the oxidant/antioxidant imbalance. The protective effect of auxin due to defence against oxygen free radicals production in retinal tissue. Also, auxin inhibit formation of AGEs and inhibit release of inflammatory mediators. It was concluded that, auxin may be used as promising therapeutic agents against diabetic complications.

Characterization of the Oral Microbiome Among Children With Type 1 Diabetes Compared With Healthy Children

Aim: Current microbiome profiling of type 1 diabetes mellitus (T1D) patients is mostly limited to gut microbiome. We characterized the oral microbiome associated with T1D in children after the onset of the disease and explored its relationship with oral physiological factors and dental status. Methods: This cohort study comprised 37 children aged 5-15 years with T1D and 29 healthy children matched in age and gender. Unstimulated whole saliva was collected from diabetic and non-diabetic children, in the morning after brushing their teeth and a fasting period of at least 1 h before sampling. 16S rRNA gene-based analysis was performed by Powersoil Pro kit by Qiagen and Phusion High-Fidelity PCR Master Mix. Oral physiological and dental parameters studied included decayed, missing, and filled teeth index, salivary flow rate, and salivary pH, glucose, calcium, phosphate, and urea levels. Results: Of the identified 105 different genera and 211 different species, the most abundant genera were Streptococcus, Prevotella, Veillonella, Haemophilus, and Neisseria. Streptococcus was more abundant in T1D children. The diabetes group had 22 taxa at the genus level and 33 taxa at the species level that were not present in the control group and the control group exhibited 6 taxa at the genus level and 9 taxa at the species level that did not exist in the diabetes group. In addition, Catonella, Fusobacterium, and Mogibacterium differed between healthy and T1D subjects. Eight species and eight subspecies were significantly more abundant among healthy children than in T1D children. Porphyromonas and Mogibacterium genera were significantly correlated with salivary parameters. We found similarities between taxa revealed in the present study and those found in gut microbiome in type 1 diabetes mellitus according to gutMDisorder database. Conclusions: Salivary microbiome analysis revealed unique microbial taxa that differed between T1D children and healthy subjects. Several genera found in the saliva of T1D children were associated with gut microbiome in T1D individuals.

Evaluation of Macular and Retinal Nerve Fiber Layer Thickness in Children with Type 1 Diabetes Mellitus without Retinopathy

PURPOSE

There are limited data from Asian countries regarding retinal thickness in children with type 1 diabetes mellitus (T1DM). This study aimed to compare the macular and retinal nerve fiber layer (RNFL) parameters between diabetic children without retinopathy and non-diabetic healthy children. We also evaluated the factors associated with RNFL thickness in children with T1DM.

METHODS

A comparative cross-sectional study was conducted among children with T1DM and healthy children aged 7 to 17 years old in Hospital Universiti Sains Malaysia from 2017 to 2019. Children with retinal disease or glaucoma were excluded. Macular and RNFL thicknesses were measured using spectral-domain optical coherence tomography. Demographic information, duration of diabetes, blood pressure, body mass index, visual acuity, and retinal examination findings were documented. Glycosylated hemoglobin levels, renal function, and blood lipid levels were also collected.

RESULTS

Forty-one children with T1DM and 80 age- and sex-matched children were enrolled. Both sexes were affected. Mean duration of diabetes mellitus was 3.66 years. The mean glycated hemoglobin levels in the T1DM group was 9.99%. The mean macular and RNFL thicknesses in children with T1DM were 277.56 (15.82) µm and 98.85 (12.05) µm, respectively. Children with T1DM had a significantly thinner average macula, superior outer macula, nasal outer macula, mean RNFL, and inferior RNFL thickness compared to controls (p < 0.05). There was a significant association between nephropathy and the mean RNFL thickness.

CONCLUSIONS

Children with T1DM had significantly decreased mean macular and RNFL thicknesses. Nephropathy is associated with an increased RNFL thickness.

Advanced glycation end products as predictors of renal function in youth with type 1 diabetes

To examine if skin autofluorescence (sAF) differed in early adulthood between individuals with type 1 diabetes and age-matched controls and to ascertain if sAF aligned with risk for kidney disease. Young adults with type 1 diabetes (N = 100; 20.0 ± 2.8 years; M:F 54:46; FBG-11.6 ± 4.9 mmol/mol; diabetes duration 10.7 ± 5.2 years; BMI 24.5(5.3) kg/m²) and healthy controls (N = 299; 20.3 ± 1.8 years; M:F-83:116; FBG 5.2 ± 0.8 mmol/L; BMI 22.5(3.3) kg/m²) were recruited. Skin autofluorescence (sAF) and circulating AGEs were measured. In a subset of both groups, kidney function was estimated by GFR_{CKD-EPI CysC} and uACR, and DKD risk defined by uACR tertiles. Youth with type 1 diabetes had higher sAF and BMI, and were taller than controls. For sAF, 13.6% of variance was explained by diabetes duration, height and BMI (P_model = 1.5 × 10^-12). In the sub-set examining kidney function, eGFR and sAF were higher in type 1 diabetes versus controls. eGFR and sAF predicted 24.5% of variance in DKD risk (P_model = 2.2 × 10^-9), which increased with diabetes duration (51%; P_model < 2.2 × 10^-16) and random blood glucose concentrations (56%; P_model < 2.2 × 10^-16). HbA_1C and circulating fructosamine albumin were higher in individuals with type 1 diabetes at high versus low DKD risk. eGFR was independently associated with DKD risk in all models. Higher eGFR and longer diabetes duration are associated with DKD risk in youth with type 1 diabetes. sAF, circulating AGEs, and urinary AGEs were not independent predictors of DKD risk. Changes in eGFR should be monitored early, in addition to uACR, for determining DKD risk in type 1 diabetes.

Examination of the Effectiveness of the Healthy Empowered Active Lifestyles (HEAL) Program on Advanced Glycation End Products

This pilot study investigated the effectiveness of the healthy empowered active lifestyles (HEAL) program to reduce circulatory levels of advanced glycation end products (AGEs) and assess its relationship to BMI, % body fat, fasting glucose, and A1C. The HEAL program was delivered at a local wellness center using a team-based approach and focused on physical activity and dietary education. A sample of twenty primarily European American (19 white, 1 black) participants (i.e., 10 males, 10 females) aged 26 to 71 (m = 48.75 ± 10.26) completed 12 weeks of the HEAL intervention. Pre to post changes in AGEs, BMI, % body fat, fasting glucose, and A1C were examined as primary outcomes. The findings showed participants had the following average reductions: AGEs 36.04 ± 18.48 ug/mL, BMI 2.0 ± 1.2 kg/m2, % body fat 3.18 ± 1.57%, fasting glucose 5.9 ± 17.21 mg/dL, and A1C 0.68 ± 1.11%. All twenty participants successfully completed the entire twelve weeks of the HEAL intervention. The results of this study show that the HEAL intervention provides beneficial reductions of AGEs, BMI, % body fat, fasting glucose, and A1C. In addition, the high adherence shows promise, and demonstrates the potential for HEAL as a behavioral intervention to improve pre-diabetic and other inflammatory related comorbidities. Further replication of results via additional randomized controlled trials is needed.

Development and Progression of Non-Alcoholic Fatty Liver Disease: The Role of Advanced Glycation End Products

Non-alcoholic fatty liver disease (NAFLD) affects up to 30% of the adult population and is now a major cause of liver disease-related premature illness and deaths in the world. Treatment is largely based on lifestyle modification, which is difficult to achieve in most patients. Progression of simple fatty liver or steatosis to its severe form non-alcoholic steatohepatitis (NASH) and liver fibrosis has been explained by a 'two-hit hypothesis'. Whilst simple steatosis is considered the first hit, its transformation to NASH may be driven by a second hit. Of several factors that constitute the second hit, advanced glycation end products (AGEs), which are formed when reducing-sugars react with proteins or lipids, have been implicated as major candidates that drive steatosis to NASH via the receptor for AGEs (RAGE). Both endogenous and processed food-derived (exogenous) AGEs can activate RAGE, mainly present on Kupffer cells and hepatic stellate cells, thus propagating NAFLD progression. This review focuses on the pathophysiology of NAFLD with special emphasis on the role of food-derived AGEs in NAFLD progression to NASH and liver fibrosis. Moreover, the effect of dietary manipulation to reduce AGE content in food or the therapies targeting AGE/RAGE pathway on disease progression is also discussed.

Adipose Tissue Protein Glycoxidation is Associated with Weight-Loss Potential

OBJECTIVE

This study aimed to characterize the differences in protein oxidation biomarkers in adipose tissue (AT) as an indicator of AT metabolism and bariatric surgery weight-loss success.

METHODS

A human model, in which sixty-five individuals with obesity underwent bariatric surgery, and a diet-induced obesity animal model, in which animals were treated for 2 months with normocaloric diets, were analyzed to determine the associations between AT protein oxidation and body weight loss. Protein oxidative biomarkers were determined by gas chromatography/mass spectrometry in AT from human volunteers before the surgery, as well as 2 months after a diet treatment in the animal model.

RESULTS

The levels of carboxyethyl-lysine (CEL) and 2-succinocystein (2SC) in both visceral and subcutaneous AT before the surgery directly correlated with greater weight loss in both human and animal models. 2SC levels in subcutaneous AT greater than 4.7 × 10⁶  μmol/mol lysine (95% CI: 3.4 × 10⁶ to 6.0 × 10⁶ ) may predict greater weight loss after bariatric surgery (receiver operating characteristic curve area = 0.8222; P = 0.0047). Additionally, it was observed that individuals with diabetes presented lower levels of CEL and 2SC in subcutaneous AT (P = 0.0266 and P = 0.0316, respectively) compared with individuals without diabetes.

CONCLUSIONS

CEL and 2SC in AT are useful biomarkers of AT metabolism and predict the individual's ability to reduce body weight after bariatric surgery.

Plasma markers of oxidative status were associated with increasing continuous cardiometabolic risk scores in healthy students aged 16-20 years without central obesity

AIM

We studied the association between increased cardiometabolic risk and markers of oxidative status and glycation in apparently healthy subjects who did not present with central obesity.

METHODS

From 2011 to 2012, we recruited 2064 students (53% girls) aged 16-20 years from Western Slovakia. Their continuous metabolic syndrome scores (MSS) were calculated as a mean of the sum of the z-scores of waist-to-height ratio, mean arterial pressure, triacylglycerols, high-density lipoprotein-cholesterol and quantitative insulin sensitivity check index. Plasma markers of protein glycation and oxidation, lipid peroxidation and total antioxidant status were analysed.

RESULTS

In both genders, advanced oxidation protein products (AOPPs) increased across the MSS quintiles (p < 0.001). AOPPs and fructosamines were significant predictors of the MSS in both genders. Moreover, high-sensitivity C-reactive protein, leukocyte counts and advanced glycation end-products (AGEs) contributed significantly in girls. Triacylglycerols, fructosamines, AGEs and total antioxidant capacity correlated significantly with AOPPs in both genders.

CONCLUSION

Advanced oxidation protein products may act as inflammatory mediators that contribute to the development of cardiometabolic afflictions. Determining these may provide information related to cardiometabolic risk and represent potential target to reduce or prevent irreversible oxidative stress-induced cellular damage.

Progress in Metabonomics of Type 2 Diabetes Mellitus

With the improvement of living standards and a change in lifestyle, the incidence of type 2 diabetes mellitus (T2DM) is increasing. Its etiology is too complex to be completely understand yet. Metabonomics techniques are used to study the changes of metabolites and metabolic pathways before and after the onset of diabetes and make it more possible to further understand the pathogenesis of T2DM and improve its prediction, early diagnosis, and treatment. In this review, we summarized the metabonomics study of T2DM in recent years and provided a theoretical basis for the study of pathogenesis and the effective prevention and treatment of T2DM.

Food restriction promotes damage reduction in rat models of type 2 diabetes mellitus

There are several animal models of type 2 diabetes mellitus induction but the comparison between models is scarce. Food restriction generates benefits, such as reducing oxidative stress, but there are few studies on its effects on diabetes. The objective of this study is to evaluate the differences in physiological and biochemical parameters between diabetes models and their responses to food restriction. For this, 30 male Wistar rats were distributed in 3 groups (n = 10/group): control (C); diabetes with streptozotocin and cafeteria-style diet (DE); and diabetes with streptozotocin and nicotinamide (DN), all treated for two months (pre-food restriction period). Then, the 3 groups were subdivided into 6, generating the groups CC (control), CCR (control+food restriction), DEC (diabetic+standard diet), DER (diabetic+food restriction), DNC (diabetic+standard diet) and DNR (diabetic+food restriction), treated for an additional two months (food restriction period). The food restriction (FR) used was 50% of the average daily dietary intake of group C. Throughout the treatment, physiological and biochemical parameters were evaluated. At the end of the treatment, serum biochemical parameters, oxidative stress and insulin were evaluated. Both diabetic models produced hyperglycemia, polyphagia, polydipsia, insulin resistance, high fructosamine, hepatic damage and reduced insulin, although only DE presented human diabetes-like alterations, such as dyslipidemia and neuropathy symptoms. Both DEC and DNC diabetic groups presented higher levels of protein carbonyl groups associated to lower antioxidant capacity in the plasma. FR promoted improvement of glycemia in DNR, lipid profile in DER, and insulin resistance and hepatic damage in both diabetes models. FR also reduced the protein carbonyl groups of both DER and DNR diabetic groups, but the antioxidant capacity was improved only in the plasma of DER group. It is concluded that FR is beneficial for diabetes but should be used in conjunction with other therapies.

Fundus autofluorescence lifetimes are increased in non-proliferative diabetic retinopathy

PURPOSE

To discriminate non-proliferative diabetic retinopathy (NPDR) patients from healthy controls by fluorescence lifetime imaging ophthalmoscopy (FLIO).

METHODS

A prototype FLIO (Heidelberg-Engineering, Heidelberg, Germany) was used to examine the retina of 33 patients and 28 controls. As increased fluorescence of the diabetic lens is known, the lenses of 34 patients and 24 controls were investigated as well. Time-resolved decay was detected in two spectral channels (ch1: 498-560 nm, ch2: 560-720 nm) and approximated by a series of three exponential functions yielding in lifetimes (τ₁ , τ₂ , τ₃ ), amplitudes (α₁ , α₂ , α₃ ) and their amplitude-weighted means (τ_m ).

RESULTS

Significant differences between patients and controls were found for all fundus lifetime components (τ_m , τ₁ -τ₃ ) as for the amplitude α₃ in both spectral channels. Channel 1 showed the largest differences: the average of mean fluorescence lifetime τ_m in the macula was 259 ± 137 ps in the patients versus 147 ± 69 ps in the controls. A logistic regression model allowed discrimination between study and control group with a sensitivity of 90.09% and a specificity of 71.4% (area under the curve: 0.865). Significantly shorter τ_m in the patients group than in the control group was detected in channel 2 in the crystalline lens (1587 ± 326 ps versus 1854 ± 384 ps, p = 0.006).

CONCLUSIONS

Fundus Fluorescence lifetimes are significantly increased in NPDR while lens lifetimes are shorter in the patient group. Lifetime changes might be indicative for the accumulation of advanced glycation end products (AGEs) which enables detection of the disease with high sensitivity and specificity possibly bearing diagnostic merit.

New isatin derivative inhibits neurodegeneration by restoring insulin signaling in brain

Diabetes is associated with neurodegeneration. Glycation ensues in diabetes and glycated proteins cause insulin resistance in brain resulting in amyloid plaques and NFTs. Also glycation enhances gliosis by promoting neuroinflammation. Currently there is no therapy available to target neurodegenration in brain therefore, development of new therapy that offers neuroprotection is critical. The objective of this study was to evaluate mechanistic effect of isatin derivative URM-II-81, an anti-glycation agent for improvement of insulin action in brain and inhibition of neurodegenration. Methylglyoxal induced stress was inhibited by treatment with URM-II-81. Also, Ser473 and Ser9 phosphorylation of Akt and GSK-3β respectively were restored by URM-II-81. Effect of URM-II-81 on axonal integrity was studied by differentiating Neuro2A using retinoic acid. URM-II-81 restored axonal length in MGO treated cells. Its effects were also studied in high fat and low dose streptozotocin induced diabetic mice where it reduced RBG levels and inhibited glycative stress by reducing HbA1c. URM-II-81 treatment also showed inhibition of gliosis in hippocampus. Histological analysis showed reduced NFTs in CA3 hippocampal region and restoration of insulin signaling in hippocampii of diabetic mice. Our findings suggest that URM-II-81 can be developed as a new therapeutic agent for treatment of neurodegenration.

How Can Diet Affect the Accumulation of Advanced Glycation End-Products in the Human Body?

The accumulation of advanced glycation end products (AGEs) is associated with the complications of diabetes, kidney disease, metabolic disorders and degenerative diseases. It is recognized that the pool of glycation products found in the human body comes not only from an endogenous formation, but also from a dietary exposure to exogenous AGEs. In recent years, the development of pharmacologically-active ingredients aimed at inhibiting endogenous glycation has not been successful. Since the accumulation of AGEs in the human body appears to be progressive throughout life, an early preventive action against glycation could be effective through dietary adjustments or supplementation with purified micronutrients. The present article provides an overview of current dietary strategies tested either in vitro, in vivo or both to reduce the endogenous formation of AGEs and to limit exposure to food AGEs.

Diabetes and increased lipid peroxidation are associated with systemic inflammation even in well-controlled patients

BACKGROUND

The effect of the interaction between type 2 diabetes and dyslipidemia on inflammation and lipid peroxidation (LPO) has not been assessed.

AIM

To investigate whether diabetes coupled with dyslipidemia alters oxidative metabolism leading to increased LPO products and inflammatory status.

METHODS

100 patients were divided into four groups based upon diabetic and dyslipidemic status: poorly controlled diabetes with dyslipidemia (DM-PC/D), well-controlled diabetes with dyslipidemia (DM-WC/D), normoglycemic individuals with dyslipidemia (NG/D), and normoglycemic individuals without dyslipidemia (NG/ND). Plasma was evaluated for an LPO product (MDA), antioxidant levels and inflammatory cytokines.

RESULTS

Diabetics presented significantly higher levels of LPO (p<0.05) and the DM-PC/D had higher levels of proinflammatory cytokines and MDA in the plasma in comparison with normoglycemics (p<0.05). Interestingly IL1-β, IL-6, and TNF-α in DM-WC/D were not statistically different from those in DM-PC/D. Normoglycemic individuals with dyslipidemia presented significantly increased levels of IL-6 and TNF-α when compared to normoglycemic without dyslipidemia (p<0.05). MDA levels were also positively correlated with the presence of DM complications (r=0.42, p<0.01).

CONCLUSIONS

These findings show that dyslipidemia is associated with an increased inflammatory status, even in well-controlled diabetics and in normoglycemics. Our results suggest that lipid metabolism and peroxidation are important for the development of inflammation, which is elevated in several complications associated with diabetes.

Evaluation of Ischemia-Modified Albumin, Malondialdehyde, and Advanced Oxidative Protein Products as Markers of Vascular Injury in Diabetic Nephropathy

AIM

This study aimed at evaluation of ischemia-modified albumin (IMA), malondialdehyde (MDA), and advanced oxidative protein products (AOPP) as markers of vascular injury in diabetic nephropathy (DN) with derivation of cutoff values for the same.

MATERIALS AND METHODS

Study population comprised 60 diabetes patients and 30 controls, with diabetes patients further categorized into three groups based on urine albumin/creatinine ratio (UACR) of <30 mg/g (diabetes without microalbuminuria), 30–300 mg/g (early DN), and >300 mg/g of creatinine (overt DN). Serum IMA, MDA, and AOPP were estimated by enzyme-linked immunosorbent assay; HbA1c, serum creatinine, urine albumin, and urine creatinine were estimated using automated analyzers. Statistical analysis was done using analysis of variance, Pearson’s correlation coefficient, and receiver-operating characteristic curve.

RESULTS

A statistically significant difference was found in the levels of IMA among patients with early DN (154 ng/mL), diabetes without nephropathy (109.4 ng/mL), and healthy controls (45.7 ng/mL), with highest levels in early DN cases. Similar increase was seen in AOPP as well. A significant correlation was observed between IMA and UACR in diabetes without nephropathy (r = 0.448).

CONCLUSION

The present study postulates serum IMA as a novel biomarker for the assessment of disease progression in diabetes even before microalbuminuria, and a cutoff point ≥99 ng/mL can be used for detection of early DN.

Early Formation of Serum Advanced Glycation End-Products in Children with Type 1 Diabetes Mellitus: Relationship with Glycemic Control

OBJECTIVES

To quantify serum advanced glycation end-products (AGEs) at the onset of type 1 diabetes mellitus and to determine their potential usefulness as retrospective indicators of glycemic balance.

STUDY DESIGN

Carboxymethyllysine (CML) and pentosidine concentrations were determined by liquid chromatography-tandem mass spectrometry in 3 groups of children with type 1 diabetes mellitus: group (Gr) 1, subjects included at disease onset (n = 36); Gr2, subjects with diabetes of 5 years duration (n = 48); Gr3, subjects with diabetes of 10 years duration and in control subjects (n = 33). Hemoglobin A1c (HbA1c) values were recorded over the entire course of treatment for assessing long-term glycemic balance.

RESULTS

Serum AGE concentrations were increased in all groups of subjects with diabetes compared with control subjects, but were highest in Gr1 (for CML: 0.155, 0.306, 0.219, and 0.224 mmol/mol Lys in control, Gr1, Gr2, and Gr3 subjects, respectively; for pentosidine: 312, 492, 365, and 403 nmol/mol Lys, respectively). AGE concentrations were closely correlated with HbA1c values (r = 0.78 for CML; r = 0.49 for pentosidine). In Gr2 and Gr3, the overall glycemic balance estimated by average HbA1c values was positively correlated with CML and pentosidine concentrations, especially in the first year of follow-up.

CONCLUSION

Our results indicate that AGE concentrations are elevated in serum at the time of diabetes mellitus diagnosis, suggesting that the deleterious role of AGEs in the development of long-term complications should be taken into account even at the initial stages of the disease. Moreover, in some circumstances, AGEs could serve as surrogate markers of HbA1c for monitoring glycemic control.

Differences in biochemical bone markers by diabetes type and the impact of glucose

BACKGROUND

Diabetes mellitus is associated with an increased fracture risk, however the fracture risk is 7 fold increased in patients with type 1 diabetes (T1D) and 1.4 fold increased in patients with type 2 diabetes (T2D) with decreased and increased bone mineral density, respectively. Oral ingestion of glucose causes an acute decrease in bone turnover markers, and thus glucose levels may affect bone turnover in diabetes.

OBJECTIVE

The aim was to examine disparities in bone turnover markers between patients with T1D and T2D and evaluate the effect of glucose on bone turnover.

METHODS

A cross-sectional study was conducted. Patients diagnosed with T1D (n=98) or T2D (n=96) were included from the outpatient clinics at two University Hospitals. All individuals had normal renal function. Glucose and bone turnover markers were measured in non-fasting blood samples.

RESULTS

P-procollagen type 1 amino terminal propeptide (P1NP), p-osteocalcin (OC), and s-Receptor Activator of Nuclear factor Kappa beta Ligand (RANKL) were lower in patients with T2D compared to T1D, and s-osteoprotegerin (OPG) was higher in T2D. P-C-terminal cross-linked telopeptide of type-I collagen (CTX), p-fibroblast growth factor-23 (FGF-23), p-sclerostin, and p-undercarboxylated osteocalcin (ucOC) were similar in between the two groups of patients. Increasing non-fasting glucose levels were inversely related to p-CTX, p-P1NP, p-OC, and p-ucOC and directly related to s-OPG in simple linear and multiple linear regressions adjusted for factors influencing bone turnover markers including HbA1c.

CONCLUSION

Bone turnover markers were lower in patients with T2D compared to T1D. Acute blood glucose alterations may change bone turnover mediated by OPG and have detrimental effects on bone health in diabetes.

TRIAL REGISTRATION NUMBER

ClinicalTrials.govNCT01870557.

Biomarkers in diabetic retinopathy and the therapeutic implications

The main problem both in type 1 (T1DM) and type 2 (T2DM) diabetes is the development of chronic vascular complications encompassing micro- as well as macrocirculation. Chronic complications lower the quality of life, lead to disability, and are the cause of premature death in DM patients. One of the chronic vascular complications is a diabetic retinopathy (DR) which leads to a complete loss of sight in DM patients. Recent trials show that the primary cause of diabetic retinopathy is retinal neovascularization caused by disequilibrium between pro- and antiangiogenic factors. Gaining knowledge of the mechanisms of action of factors influencing retinal neovascularization as well as the search for new, effective treatment methods, especially in advanced stages of DR, puts special importance on research concentrating on the implementation of biological drugs in DR therapy. At present, it is antivascular endothelial growth factor and antitumor necrosis factor that gain particular significance.

Advanced glycation endproducts in children with diabetes

OBJECTIVES

To estimate skin content of advanced glycation endproducts (AGEs) by measurements of skin intrinsic fluorescence (SIF) from youth with diabetes in comparison with a population of youth and adults without diabetes.

STUDY DESIGN

Using a specialized instrument, skin AGEs were estimated from skin auto-fluorescence induced at 420 nm and corrected for skin pigmentation (SIF420[kx0.5, km0.5]) in children with types 1 and 2 diabetes, as well as children and adults without diabetes. The effect of age, sex, ethnicity, and diabetes status on SIF420[kx0.5, km0.5] was analyzed.

RESULTS

SIF420[kx0.5, km0.5] increased with chronologic age and was higher in children with diabetes compared with children without diabetes (P = .0001). SIF420[kx0.5, km0.5] from 43% of children with type 1 diabetes and 55% with type 2 diabetes overlapped the range of adults without diabetes. SIF420[kx0.5, km0.5] was higher in girls than boys in patients with diabetes patients. However, there was no effect of sex or race on SIF420[kx0.5, km0.5] in subjects without diabetes.

CONCLUSIONS

After 4-6 years' exposure to diabetes, many children will have precociously high estimates of skin AGEs, comparable with levels that would naturally accumulate only after ∼25 years of chronologic aging. Potentially, this technology identifies children who are at increased risk for complications.

Metabolomics in human type 2 diabetes research

The high prevalence of diabetes and diabetic complications has caused a huge burden on the modern society. Although scientific advances have led to effective strategies for preventing and treating diabetes over the past several decades, little progress has been made toward curing the disease or even getting it under control, from a public health and overall societal standpoint. There is still a lack of reliable biomarkers indicative of metabolic alterations associated with diabetes and different drug responses, highlighting the need for the development of early diagnostic and prognostic markers for diabetes and diabetic complications. The emergence of metabolomics has allowed researchers to systemically measure the small molecule metabolites, which are sensitive to the changes of both environmental and genetic factors and therefore, could be regarded as the link between genotypes and phenotypes. During the last decade, the progression made in metabolomics has provided insightful information on disease development and disease onset prediction. Recent studies using metabolomics approach coupled with statistical tools to predict incident diabetes revealed a number of metabolites that are significantly altered, including branched-chain and aromatic amino acids, such as isoleucine, leucine, valine, tyrosine and phenylalanine, as diagnostic or highly-significant predictors of future diabetes. This review summarizes the current findings of metabolomic studies in human investigations with the most common form of diabetes, type 2 diabetes.

Threshold serum concentrations of tumour necrosis factor alpha (TNFα) as a potential marker of the presence of microangiopathy in children and adolescents with type 1 diabetes mellitus (T1DM)

The aim of this study was to estimate the threshold serum concentrations of advanced glycation end products (AGEs) and their soluble receptors (sRAGE) as well as tumour necrosis factor alpha (TNFα), vascular endothelial growth factor(165) (VEGF(165)) and interleukin-12 (IL-12) in predicting the occurrence of microangiopathy in children and adolescents with type 1 diabetes mellitus (T1DM). We studied 88 children and adolescents (age range: 6-20 yrs) with T1DM and 32 control subjects (age range: 7-20 yrs). All study participants had their daily urinary albumin excretion, HbA1c and serum creatinine levels measured, and underwent an eye examination and 24-h blood pressure monitoring. Moreover, serum concentrations of AGEs, sRAGE, TNFα, VEGF(165) and IL-12 were measured. In order to calculate the threshold values of the studied parameters, the Receiver Operating Characteristic (ROC) curve analysis was used. The results of our study have shown that among all the studied parameters a discriminative ability was found for TNFα, VEGF(165), duration of the disease, serum AGEs concentrations and daily urinary albumin excretion. However, the highest value of the area under the ROC curve (AUC(ROC)) in predicting the occurrence of diabetic microangiopathy was found for serum TNFα concentrations with its threshold value of 1.7 pg/ml [AUC(ROC) = 0.88 (95% CI: 0.79-0.97)]. The sensitivity and specificity for this variable was at the level of 85.7% and 94.3%, respectively. In conclusion, according to our results serum TNFα concentrations over 1.7 pg/ml may point to the presence of diabetic microangiopathy in children and adolescents T1DM.

Natural history of age-related retinal lesions that precede AMD in mice fed high or low glycemic index diets

PURPOSE

Epidemiologic data indicate that people who consume low glycemic index (GI) diets are at reduced risk for the onset and progression of age-related macular degeneration (AMD). The authors sought corroboration of this observation in an animal model.

METHODS

Five- and 16-month-old C57BL/6 mice were fed high or low GI diets until they were 17 and 23.5 months of age, respectively. Retinal lesions were evaluated by transmission electron microscopy, and advanced glycation end products (AGEs) were evaluated by immunohistochemistry.

RESULTS

Retinal lesions including basal laminar deposits, loss of basal infoldings, and vacuoles in the retinal pigment epithelium were more prevalent in the 23.5- than in the 17-month-old mice. Within each age group, consumption of a high GI diet increased the risk for lesions and the risk for photoreceptor abnormalities and accumulation of AGEs.

CONCLUSIONS

Consuming high GI diets accelerates the appearance of age-related retinal lesions that precede AMD in mice, perhaps by increasing the deposition of toxic AGEs in the retina. The data support the hypothesis that consuming lower GI diets, or simulation of their effects with nutraceuticals or drugs, may protect against AMD. The high GI-fed C57BL/6 mouse is a new model of age-related retinal lesions that precede AMD and mimic the early stages of disease and may be useful for drug discovery.

Biomarkers of oxidative stress in red blood cells

BACKGROUND

Exposure to high concentrations of oxygen radicals, the lack of nucleus and mitochrondria, inability to synthesise new protein and degradation of detoxifying enzymes makes red blood cells (RBCs) uniquely vulnerable to oxidative stress. This review summarizes the changes in biochemical parameters that primarily contribute to alterations in red blood cells during oxidative stress.

METHODS

PubMed, Science Direct and Springer online databases and updates from the Indian Council of Medical Research (ICMR).

RESULTS AND CONCLUSION

As one of the first cells to be affected by changes in the redox status of the body, alterations in red blood cells are widely used in first step-diagnoses of a number of pathological conditions. The information presented in this review provides an update on biomarkers of redox balance in red blood cells. These biomarkers may be used for assessment of oxidative stress during human health and disease.

Oxidative stress and diabetes mellitus

Increasing evidences have suggested that oxidative stress plays a major role in the pathogenesis of diabetes mellitus (DM). Oxidative stress also appears to be the pathogenic factor in underlying diabetic complications. Reactive oxygen species (ROS) are generated by environmental factors, such as ionizing radiation and chemical carcinogens, and also by endogenous processes, including energy metabolism in mitochondria. ROS produced either endogenously or exogenously can attack lipids, proteins and nucleic acids simultaneously in living cells. There are many potential mechanisms whereby excess glucose metabolites traveling along these pathways might promote the development of DM complication and cause pancreatic β cell damage. However, all these pathways have in common the formation of ROS, that, in excess and over time, causes chronic oxidative stress, which in turn causes defective insulin gene expression and insulin secretion as well as increased apoptosis. Various methods for determining biomarkers of cellular oxidative stress have been developed, and some have been proposed for sensitive assessment of antioxidant defense and oxidative damage in diabetes and its complications. However, their clinical utility is limited by less than optimal standardization techniques and the lack of sufficient large-sized, multi-marker prospective trials.

Low levels of asymmetric dimethylarginine in children with diabetes mellitus type I compared with healthy children

OBJECTIVE

Although high levels of asymmetric dimethylarginine (ADMA) are associated with an increased risk for vasculopathy in adults, elevated ADMA concentrations also have been found in healthy young children. Patients with diabetes mellitus type 1 (DM1) are at risk for vasculopathy, and because the function of ADMA in the development of vascular symptoms is incompletely understood, we investigated ADMA concentrations in pediatric patients with DM1 compared with healthy age- and sex-matched individuals.

STUDY DESIGN

This cross-sectional study included 85 pediatric patients with DM1 and 89 age- and sex-matched healthy controls.

RESULTS

ADMA concentrations were significantly lower in the patients with DM1 and were inversely correlated with hemoglobin A1c concentrations.

CONCLUSIONS

Besides its vasoprotective function, nitric oxide itself may exert oxidative stress by generating free radicals. In these circumstances, ADMA would protect the system from nitric oxide overproduction and perpetuation of oxidative stress. This theory is supported by the physiologically higher ADMA concentrations in healthy children. Thus, low ADMA concentrations in children with DM1 may be an indicator of impaired protection against oxidative stress.

Variants of the adenosine A(2A) receptor gene are protective against proliferative diabetic retinopathy in patients with type 1 diabetes

AIMS

The adenosine A(2A) receptor (ADORA(2A)) may ameliorate deleterious physiologic effects associated with tissue injury in individuals with diabetes. We explored associations between variants of the ADORA(2A) gene and proliferative diabetic retinopathy (PDR) in a cohort of patients with type 1 diabetes (T1D).

METHODS

The participants were from the Pittsburgh Epidemiology of Diabetes Complications prospective study of childhood-onset T1D. Stereoscopic photographs of the retinal fundus taken at baseline, then biennially, for 10 years were used to define PDR according to the modified Airlie House system. Two tagging single nucleotide polymorphisms (tSNPs; rs2236624-C/T and rs4822489-G/T) in the ADORA(2A) gene were selected using the HapMap (haplotype map) reference database.

RESULTS

A significant association was observed between SNP rs2236624 and PDR in the recessive genetic model. Participants homozygous for the T allele displayed a decreased risk of developing prevalent PDR (odds ratio, OR = 0.36; p = 0.04) and incident PDR (hazard ratio = 0.156; p = 0.009), and for all cases of PDR combined (OR = 0.23; p = 0.001). The protective effect of T allele homozygosity remained after adjusting for covariates. Similarly, for SNP rs4822489, an association between PDR and T allele homozygosity was observed following covariate adjustment (OR = 0.55; 95% CI: 0.31-0.92; p = 0.04).

CONCLUSION

Genetic variants of ADORA(2A) offer statistically significant protection against PDR development in patients with T1D.

Protein oxidation biomarkers in plasma of type 2 diabetic patients

OBJECTIVES

To evaluate oxidative stress and the extent of oxidation of plasma proteins in type 2 diabetic patients.

DESIGN AND METHODS

Study was carried out on blood from 31 diabetic patients of both sexes (mean age = 58 + or - 7; duration of diabetes 12 + or - 5 years) and healthy age and sex matched normal subjects. Biomarkers of protein oxidation; plasma protein carbonyls (PCO), advanced oxidation protein products (AOPPs) and -SH group and free radical scavenging capacity of plasma was measured.

RESULTS

PCO and AOPPS levels were significantly (P<0.005) higher in diabetic patients in comparison to healthy volunteers. Reduced free radical scavenging capacity (P<0.001) and -SH group (P<0.05) was observed in plasma of type 2 diabetic patients.

CONCLUSIONS

Our data suggest that diabetics are susceptible to protein oxidation. Oxidative modulation of proteins due to reduced radical scavenging activity of plasma patients may be one of the reasons of altered physiological processes in type 2 diabetic patients.