Metformin-Associated Gastrointestinal Adverse Events Are Reduced by Probiotics: A Meta-Analysis.

Metformin, one of the most frequently used oral glucose-lowering drugs (GLDs), is associated with the occurrence of gastrointestinal (GI) adverse events in approximately 20% of users. These unwanted actions result in non-compliance or even discontinuation of metformin therapy. The aim of the presented meta-analysis was to determine whether adding a drug from the group of sulfonylureas, glitazones, DPP-IV inhibitors, or probiotics to metformin monotherapy may affect the risk of GI side effects. The material for this meta-analysis comprised data from 26 randomized controlled clinical trials (RCTs) published in English. This meta-analysis included 41,048 patients. The PubMed, Cochrane Library, and Clinical Trials databases were thoroughly searched to find relevant RCTs. The Population, Intervention, Comparison, Outcomes, and Study Type (PICOT) structure was used to formulate study selection criteria and the research question. Cochrane Review Manager Software 5.4 was used to carry out analysis of collected data. The results were presented as relative risk (RR) and 95% confidence interval (95% CI) for each group, and p < 0.05 was considered as statistically significant. As expected from clinical practice, metformin was associated with a markedly increased risk of abdominal pain, nausea, and vomiting compared to placebo. In comparison to other GLDs, taking metformin was related to an elevated risk of diarrhea and abdominal pain and to a lowered risk of vomiting and bloating. In turn, adding other GLDs to metformin treatment was associated with an elevated risk of nausea and vomiting than treatment with metformin in monotherapy. However, adding probiotics to metformin therapy was related to a decreased risk of diarrhea, bloating, and constipation. The obtained results demonstrate that the combination of metformin with other GLDs may elevate the risk of nausea and vomiting, whereas combination with probiotics decreases the risk of diarrhea, bloating, and constipation. Thus, the results of our meta-analysis suggest that probiotics may reduce the risk of some GI side effects in people with type 2 diabetes mellitus (T2DM) who started treatment with metformin.

Association of Glutathione Peroxidase 3 (GPx3) and miR-196a with Carbohydrate Metabolism Disorders in the Elderly.

The escalating prevalence of carbohydrate metabolism disorders (CMDs) prompts the need for early diagnosis and effective markers for their prediction. Hyperglycemia, the primary indicator of CMDs including prediabetes and type 2 diabetes mellitus (T2DM), leads to overproduction of reactive oxygen species (ROS) and oxidative stress (OxS). This condition, resulting from chronic hyperglycemia and insufficient antioxidant defense, causes damage to biomolecules, triggering diabetes complications. Additionally, aging itself can serve as a source of OxS due to the weakening of antioxidant defense mechanisms. Notably, previous research indicates that miR-196a, by downregulating glutathione peroxidase 3 (GPx3), contributes to insulin resistance (IR). Additionally, a GPx3 decrease is observed in overweight/obese and insulin-resistant individuals and in the elderly population. This study investigates plasma GPx3 levels and miR-196a expression as potential CMD risk indicators. We used ELISA to measure GPx3 and qRT-PCR for miR-196a expression, supplemented by multivariate linear regression and receiver operating characteristic (ROC) analysis. Our findings included a significant GPx3 reduction in the CMD patients (n = 126), especially in the T2DM patients (n = 51), and a decreasing trend in the prediabetes group (n = 37). miR-196a expression, although higher in the CMD and T2DM groups than in the controls, was not statistically significant, potentially due to the small sample size. In the individuals with CMD, GPx3 levels exhibited a negative correlation with the mass of adipose tissue, muscle, and total body water, while miR-196a positively correlated with fat mass. In the CMD group, the analysis revealed a weak negative correlation between glucose and GPx3 levels. ROC analysis indicated a 5.2-fold increased CMD risk with GPx3 below 419.501 ng/mL. Logistic regression suggested that each 100 ng/mL GPx3 increase corresponded to a roughly 20% lower CMD risk (OR = 0.998; 95% CI: 0.996-0.999; p = 0.031). These results support the potential of GPx3 as a biomarker for CMD, particularly in T2DM, and the lack of a significant decline in GPx3 levels in prediabetic individuals suggests that it may not serve reliably as an early indicator of CMDs, warranting further large-scale validation.

Targeted inhibition of the ATR/CHK1 pathway overcomes resistance to olaparib and dysregulates DNA damage response protein expression in BRCA2MUT ovarian cancer cells.

Olaparib is a PARP inhibitor (PARPi) approved for targeted treatment of ovarian cancer (OC). However, its efficacy is impeded by the inevitable occurrence of resistance. Here, we investigated whether the cytotoxic activity of olaparib could be synergistically enhanced in olaparib-resistant OC cells with BRCA2 reversion mutation by the addition of inhibitors of the ATR/CHK1 pathway. Moreover, we provide insights into alterations in the DNA damage response (DDR) pathway induced by combination treatments. Antitumor activity of olaparib alone or combined with an ATR inhibitor (ATRi, ceralasertib) or CHK1 inhibitor (CHK1i, MK-8776) was evaluated in OC cell lines sensitive (PEO1, PEO4) and resistant (PEO1-OR) to olaparib. Antibody microarrays were used to explore changes in expression of 27 DDR-related proteins. Olaparib in combination with ATR/CHK1 inhibitors synergistically induced a decrease in viability and clonogenic survival and an increase in apoptosis mediated by caspase-3/7 in all OC cells. Combination treatments induced cumulative alterations in expression of DDR-related proteins mediating distinct DNA repair pathways and cell cycle control. In the presence of ATRi and CHK1i, olaparib-induced upregulation of proteins determining cell fate after DNA damage (PARP1, CHK1, c-Abl, Ku70, Ku80, MDM2, and p21) was abrogated in PEO1-OR cells. Overall, the addition of ATRi or CHK1i to olaparib effectively overcomes resistance to PARPi exerting anti-proliferative effect in BRCA2MUT olaparib-resistant OC cells and alters expression of DDR-related proteins. These new molecular insights into cellular response to olaparib combined with ATR/CHK1 inhibitors might help improve targeted therapies for olaparib-resistant OC.

Non-Alcoholic Fatty Liver Disease Is Associated with a Decreased Catalase (CAT) Level, CT Genotypes and the T Allele of the -262 C/T CAT Polymorphism.

BACKGROUND: It is well known that oxidative stress plays an important role in the development of non-alcoholic fatty liver disease (NAFLD). It has been suggested that an insufficient antioxidant defense system composed of antioxidant enzymes, including catalase (CAT) and nonenzymatic molecules, is a key factor triggering oxidative damage in the progression of liver disease. Therefore, the aim of our study was to assess whether the level of CAT and -262 C/T polymorphism in the promoter of CAT (rs1001179) are associated with NAFLD. METHODS: In total, 281 adults (152/129 female/male, aged 65.61 ± 10.44 years) were included in the study. The patients were assigned to an NAFLD group (n = 139) or a group without NAFLD (n = 142) based on the results of an ultrasound, the Hepatic Steatosis Index, and the Fatty Liver Index (FLI). CAT levels were determined using an ELISA test, and genomic DNA was extracted via the standard phenol/chloroform-based method and genotyped via RFLP-PCR. RESULTS: The CAT level was decreased in NAFLD patients (p < 0.001), and an ROC analysis revealed that a CAT level lower than 473.55 U/L significantly increases the risk of NAFLD. In turn, genotyping showed that the CT genotype and the T allele of -262 C/T CAT polymorphism elevate the risk of NAFLD. The diminished CAT level in the NAFLD group correlated with increased FLI, waist circumference and female gender. CONCLUSION: The obtained results support observations that oxidative damage associated with NAFLD may be the result of a decreased CAT level as a part of the antioxidant defense system.

Metformin Induces Apoptosis in Human Pancreatic Cancer (PC) Cells Accompanied by Changes in the Levels of Histone Acetyltransferases (Particularly, p300/CBP-Associated Factor (PCAF) Protein Levels).

Accumulating evidence (mainly from experimental research) suggests that metformin possesses anticancer properties through the induction of apoptosis and inhibition of the growth and proliferation of cancer cells. However, its effect on the enzymes responsible for histone acetylation status, which plays a key role in carcinogenesis, remains unclear. Therefore, the aim of our study was to evaluate the impact of metformin on histone acetyltransferases (HATs) (i.e., p300/CBP-associated factor (PCAF), p300, and CBP) and on histone deacetylases (HDACs) (i.e., SIRT-1 in human pancreatic cancer (PC) cell lines, 1.2B4, and PANC-1). The cells were exposed to metformin, an HAT inhibitor (HATi), or a combination of an HATi with metformin for 24, 48, or 72 h. Cell viability was determined using an MTT assay, and the percentage of early apoptotic cells was determined with an Annexin V-Cy3 Apoptosis Detection Assay Kit. Caspase-9 activity was also assessed. SIRT-1, PCAF, p300, and CBP expression were determined at the mRNA and protein levels using RT-PCR and Western blotting methods, respectively. Our results reveal an increase in caspase-9 in response to the metformin, indicating that it induced the apoptotic death of both 1.2B4 and PANC-1 cells. The number of cells in early apoptosis and the activity of caspase-9 decreased when treated with an HATi alone or a combination of an HATi with metformin, as compared to metformin alone. Moreover, metformin, an HATi, and a combination of an HATi with metformin also modified the mRNA expression of SIRT-1, PCAF, CBP, and p300. However, metformin did not change the expression of the studied genes in 1.2B4 cells. The results of the Western blot analysis showed that metformin diminished the protein expression of PCAF in both the 1.2B4 and PANC-1 cells. Hence, it appears possible that PCAF may be involved in the metformin-mediated apoptosis of PC cells.

Considerations about Cytotoxicity of Resin-Based Composite Dental Materials: A Systematic Review.

The dental material industry is rapidly developing resin-based composites (RBCs), which find widespread use in a variety of clinical settings. As such, their biocompatibility has gained increasing interest. This literature review presents a summary of research into the cytotoxicity of methacrylate-based composites published from 2017 to 2023. Subject to analysis were 14 in vitro studies on human and murine cell lines. Cytotoxicity in the included studies was measured via MTT assay, LDH assay, and WST-1 assay. The QUIN Risk of Bias Tool was performed to validate the included studies. Included studies (based entirely on the results of in vitro studies) provide evidence of dose- and time-dependent cytotoxicity of dental resin-based composites. Oxidative stress and the depletion of cellular glutathione (GSH) were suggested as reasons for cytotoxicity. Induction of apoptosis by RBCs was indicated. While composites remain the golden standard of dental restorative materials, their potential cytotoxicity cannot be ignored due to direct long-term exposure. Further in vitro investigations and clinical trials are required to understand the molecular mechanism of cytotoxicity and produce novel materials with improved safety profiles.

Irisin Is Related to Non-Alcoholic Fatty Liver Disease (NAFLD).

Irisin is a cytokine involved in many metabolic pathways occurring, among others, in muscles, adipose tissue and liver. Thus, fluctuations in irisin levels are suggested to be related to metabolic diseases. Therefore, the purpose of our study was to evaluate whether irisin may be associated with non-alcoholic fatty liver disease (NAFLD). A total of 138 patients (70/68 male/female, mean age 65.61 ± 10.44 years) were enrolled in the study. The patients were assigned to the NAFLD group (n = 72, including 46 patients with type 2 diabetes (T2DM]) and the group without NAFLD (n = 66, 31 patients with T2DM). NAFLD was diagnosed based on ultrasound examination, Hepatic Steatosis Index (HSI) and Fatty Liver Index. Baseline anthropometric, blood pressure and biochemical parameters were collected. The serum irisin level was determined using an ELISA test. We observed that NAFLD was associated with an increased concentration of irisin. Moreover, Spearman correlations and linear regression analysis revealed that irisin level correlates with some anthropometric and biochemical parameters such as body mass index, glycated hemoglobin, aspartic aminotransferase, creatinine and urea. Logistic regression analysis depicted that odds for NAFLD increase 1.17 times for each 1 µg/mL rise of irisin concentration. Finally, ROC analysis showed that the concentration of irisin possesses a discriminate capacity for NAFLD and optimal cut points concentration could be designed. The risk of NAFLD in the subgroup with irisin concentration above 3.235 µg/mL was 4.57 times higher than in patients with the lower concentration of irisin. To conclude, the obtained results suggest that irisin concentration is associated with some anthropometric and biochemical parameters and should be further investigated toward its usage as a diagnostic biomarker of NAFLD.

Metabolic Action of Metformin.

Metformin, a cheap and safe biguanide derivative, due to its ability to influence metabolism, is widely used as a first-line drug for type 2 diabetes (T2DM) treatment. Therefore, the aim of this review was to present the updated biochemical and molecular effects exerted by the drug. It has been well explored that metformin suppresses hepatic glucose production in both AMPK-independent and AMPK-dependent manners. Substantial scientific evidence also revealed that its action is related to decreased secretion of lipids from intestinal epithelial cells, as well as strengthened oxidation of fatty acids in adipose tissue and muscles. It was recognized that metformin's supra-therapeutic doses suppress mitochondrial respiration in intestinal epithelial cells, whereas its therapeutic doses elevate cellular respiration in the liver. The drug is also suggested to improve systemic insulin sensitivity as a result of alteration in gut microbiota composition, maintenance of intestinal barrier integrity, and alleviation of low-grade inflammation.

The Action of Vitamin D in Adipose Tissue: Is There the Link between Vitamin D Deficiency and Adipose Tissue-Related Metabolic Disorders?

Adipose tissue plays an important role in systemic metabolism via the secretion of adipocytokines and storing and releasing energy. In obesity, adipose tissue becomes dysfunctional and characterized by hypertrophied adipocytes, increased inflammation, hypoxia, and decreased angiogenesis. Although adipose tissue is one of the major stores of vitamin D, its deficiency is detective in obese subjects. In the presented review, we show how vitamin D regulates numerous processes in adipose tissue and how their dysregulation leads to metabolic disorders. The molecular response to vitamin D in adipose tissue affects not only energy metabolism and adipokine and anti-inflammatory cytokine production via the regulation of gene expression but also genes participating in antioxidant defense, adipocytes differentiation, and apoptosis. Thus, its deficiency disturbs adipocytokines secretion, metabolism, lipid storage, adipogenesis, thermogenesis, the regulation of inflammation, and oxidative stress balance. Restoring the proper functionality of adipose tissue in overweight or obese subjects is of particular importance in order to reduce the risk of developing obesity-related complications, such as cardiovascular diseases and diabetes. Taking into account the results of experimental studies, it seemed that vitamin D may be a remedy for adipose tissue dysfunction, but the results of the clinical trials are not consistent, as some of them show improvement and others no effect of this vitamin on metabolic and insulin resistance parameters. Therefore, further studies are required to evaluate the beneficial effects of vitamin D, especially in overweight and obese subjects, due to the presence of a volumetric dilution of this vitamin among them.

Is Vitamin D Deficiency Related to Increased Cancer Risk in Patients with Type 2 Diabetes Mellitus?

There is mounting evidence that type 2 diabetes mellitus (T2DM) is related with increased risk for the development of cancer. Apart from shared common risk factors typical for both diseases, diabetes driven factors including hyperinsulinemia, insulin resistance, hyperglycemia and low grade chronic inflammation are of great importance. Recently, vitamin D deficiency was reported to be associated with the pathogenesis of numerous diseases, including T2DM and cancer. However, little is known whether vitamin D deficiency may be responsible for elevated cancer risk development in T2DM patients. Therefore, the aim of the current review is to identify the molecular mechanisms by which vitamin D deficiency may contribute to cancer development in T2DM patients. Vitamin D via alleviation of insulin resistance, hyperglycemia, oxidative stress and inflammation reduces diabetes driven cancer risk factors. Moreover, vitamin D strengthens the DNA repair process, and regulates apoptosis and autophagy of cancer cells as well as signaling pathways involved in tumorigenesis i.e., tumor growth factor ß (TGFß), insulin-like growth factor (IGF) and Wnt-ß-Cathenin. It should also be underlined that many types of cancer cells present alterations in vitamin D metabolism and action as a result of Vitamin D Receptor (VDR) and CYP27B1 expression dysregulation. Although, numerous studies revealed that adequate vitamin D concentration prevents or delays T2DM and cancer development, little is known how the vitamin affects cancer risk among T2DM patients. There is a pressing need for randomized clinical trials to clarify whether vitamin D deficiency may be a factor responsible for increased risk of cancer in T2DM patients, and whether the use of the vitamin by patients with diabetes and cancer may improve cancer prognosis and metabolic control of diabetes.

A potential role of calpains in sulfonylureas (SUs) -mediated death of human pancreatic cancer cells (1.2B4).

Sulfonylureas (SUs) are suggested to accelerate the pancreatic ß-cells mass loss via apoptosis. However, little is known whether calpains mediate this process. The aim of the present study is to evaluate the involvement of calpains in SUs-induced death of human pancreatic cancer (PC) cell line 1.2B4. The cells were exposed to: glibenclamide, glimepiride and gliclazide for 72 h. The expression analysis of caspase-3 (CASP-3), TP53, calpain 1 (CAPN-1), calpain 2 (CAPN-2) and calpain 10 (CAPN-10) was detected using RT-PCR method. Intracellular Ca2+ concentrations, CASP-3 activity and total calpain activity were also evaluated. Our results have shown that glibenclamide and glimepiride decrease 1.2B4 cells viability with accompanied increase in intracellular Ca2+ concentration and increased expression of apoptosis-related CASP-3 and TP53. Gliclazide did not affect 1.2B4 cell viability and Ca2+ concentration, however, it downregulated CASP-3 and upregulated TP53. Interestingly, 50 µM glimepiride increased expression of CAPN-1, CAPN-2 and CAPN-10 whereas 50 µM glibenclamide solely upregulated CAPN-2 expression. We have shown that 10 µM and 50 µM glibenclamide and glimepiride increased the activity of CASP-3, but decreased total calpain activity. Our results suggest that calpains may be involved in glibenclamide- and glimepiride-induced death of PC cells. However, further investigation is required to confirm the engagement of calpains in SUs-mediated death of PC cells, especially studies on protein level of particular isoforms of calpains should be conducted.

The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders.

Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca2+ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.

Comparison of an automated microfluidic immunoassay technology (BioIC, lab-on-chips) and ImmunoCAP assay. Lab-on-chips as a tool for specific IgE (sIgE) detection.

INTRODUCTION: The measurement of clinically important specific IgE (sIgE) antibody is pivotal for both diagnosis and management of allergy. Two methods may be distinguished depending on the number of antigens tested simultaneously: singleplex and multiplex. BioIC is a multiplex, advanced, automated microfluidic immunoassay system enabling simultaneous sIgE measurement against multiple allergens. ImmunoCAP is a singleplex assay for sIgE detection and gold standard method for diagnosis of allergy. AIM: To compare and validate the diagnostic capability of a multiplex sIgE assay - BioIC assay with a singleplex ImmunoCAP assay. MATERIAL AND METHODS: Using both BioIC assay and ImmunoCAP assay, the sIgE level in serum samples from 20 allergic disease patients with respect to 33 allergens (16 inhalant allergens, 16 food allergens and 1 contact allergen) was measured. Receiver operating characteristic (ROC) area under the curve (AUC), qualitative and semi-quantitative comparisons were performed to compare both sIgE measurement methods using statistical analyses. RESULTS: ROC AUC analysis showed similar sensitivity and specificity of BioIC assay and ImmunoCAP assay. In qualitative analysis, the negative and positive agreements were 100% equal for each allergen. Spearman's rank correlation coefficients identified very high positive correlations between two assays for all tested allergens (p < 0.001). CONCLUSIONS: The BioIC showed agreement with ImmunoCAP assay. Sensitivity and specificity of both assays are similar, thus they showed similar diagnostic performance. However, careful interpretation of obtained results is necessary in clinical applications because of methodological differences between these two systems.

Light Stability, Pro-Apoptotic and Genotoxic Properties of Silver (I) Complexes of Metronidazole and 4-Hydroxymethylpyridine against Pancreatic Cancer Cells In Vitro.

Antimicrobial properties of silver (I) ion and its complexes are well recognized. However, recent studies suggest that both silver (I) ion and its complexes possess anticancer activity associated with oxidative stress-induced apoptosis of various cancer cells. In this study, we aimed to investigate whether silver nitrate and its complexes with metronidazole and 4-hydroxymethylpyridine exert anticancer action against human pancreatic cancer cell lines (PANC-1 and 1.2B4). In the study, we compared decomposition speed for silver complexes under the influence of daylight and UV-A (ultraviolet-A) rays. We employed the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazonium bromide) assay to evaluate the cytotoxicity and the alkaline comet assay to determine genotoxicity of silver nitrate and its complexes. Flow cytometry and the Annexin V-FITC/PI apoptosis detection kit were used to detect the apoptosis of human pancreatic cancer cells. We found a dose dependent decrease of both pancreatic cancer cell line viability after exposure to silver nitrate and its complexes. The flow cytometry analysis confirmed that cell death occurred mainly via apoptosis. We also documented that the studied compounds induced DNA damage. Metronidazole and 4-hydroxymethylpyridine alone did not significantly affect viability and level of DNA damage of pancreatic cancer cell lines. Complex compounds showed better stability than AgNO3, which decomposed slower than when exposed to light. UV-A significantly influences the speed of silver salt decomposition reaction. To conclude, obtained data demonstrated that silver nitrate and its complexes exerted anticancer action against human pancreatic cancer cells.

Wide-Range Effects of 1,25(OH)2D3 on Group 4A Phospholipases Is Related to Nuclear Factor κ-B and Phospholipase-A2 Activating Protein Activity in Mast Cells.

INTRODUCTION: Phospholipases are enzymes that occur in many types of human cells, including mast cells, and play an important role in the molecular background of asthma pathogenesis, and the development of inflammation NF-κB activities that affect numerous biological processes has been reported in many inflammatory diseases including asthma. Vitamin D is a widely studied factor that affects many diseases, including asthma. The aim of this study is to assess the influence of 1,25-(OH)2D3 on regulation of chosen phospholipase-A2 (PLA2) expression-selected inflammation mediators. METHODS: LUVA mast cells were stimulated with 1,25(OH)2D3, and inhibitors of NF-κB p65 and ubiquitination. Expression analysis of phospholipases (PLA2G5, PLA2G10, PLA2G12, PLA2G15, PLA2G4A, PLA2G4B, PLA2G4C, PLAA, NF-κB p65, and UBC) was done utilizing real-time PCR and Western blot. Eicosanoid (LTC4, LXA4, 15[S]-HETE, and PGE2) levels and sPLA2 were also measured. RESULTS: We found that 1,25(OH)2D3 decreased the expression of PLA2G5, PLA2G15, PLA2G5,UBC, and NF-κB p65 but increased expression of PLAA and PLA2G4C (p < 0.05). Moreover, the expression of PLA2G5 and PLA2G15 decreased after inhibition of NF-κB p65 and UBC. Increased levels of released LXA4 and 15(S)-HETE, decreased levels of LTC4, and sPLA2s enzymatic activity in response to 1,25(OH)2D3 were also observed. Additionally, NF-κB p65 inhibition led to an increase in the LXA4 concentration. CONCLUSION: Future investigations will be needed to further clarify the role of 1,25(OH)2D3 in the context of asthma and the inflammatory process; however, these results confirm a variety of effects which can be caused by this vitamin. 1,25(OH)2D3-mediated action may result in the development of new therapeutic strategies for asthma treatment.

Vitamin D Supplementation Reduces Both Oxidative DNA Damage and Insulin Resistance in the Elderly with Metabolic Disorders.

BACKGROUND: Research evidence indicates that vitamin D deficiency is involved in the pathogenesis of insulin resistance (IR) and associated metabolic disorders including hyperglycemia and dyslipidemia. It also suggested that vitamin D deficiency is associated with elevated levels of oxidative stress and its complications. Therefore, the aim of our study was to determine the effect of vitamin D supplementation on DNA damage and metabolic parameters in vitamin D deficient individuals aged >45 with metabolic disorders. Material and Methods: Of 98 initially screened participants, 92 subjects deficient in vitamin D were included in the study. They were randomly assigned to the following group: with vitamin D supplementation (intervention group, n = 48) and without supplementation (comparative group, n = 44). The patients from both groups were divided into two subgroups according to the presence or absence of type 2 diabetes (T2DM). The intervention group was treated with 2000 International Unit (IU) cholecalciferol/day between October and March for three months. At baseline and after three-month supplementation vitamin D concentration (25-OH)D3 and endogenous and oxidative DNA damage were determined. In addition, fast plasma glucose (FPG), fasting insulin, HbA1c and lipid fraction (total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), triglyceride (TG)), as well as anthropometric measurements (weight, height) were gathered. The following IR-related parameters were calculated Homeostatic Model Assesment - Insulin Resistance (HOMA-IR) and TG/HDL ratio. Results: Three-month vitamin D supplementation increased the mean vitamin D concentration to generally accepted physiological level independently of T2DM presence. Importantly, vitamin D exposure decreased the level of oxidative DNA damage in lymphocytes of patients of intervention group. Among studied metabolic parameters, vitamin D markedly increased HDL level, decreased HOMA-IR, TG/HDL ratio. Furthermore, we found that HbA1c percentage diminished about 0.5% in T2DM patients supplemented with vitamin D. Conclusion: The current study demonstrated that daily 2000I U intake of vitamin D for three months decreased the level of oxidative DNA damage, a marker of oxidative stress, independently on T2DM presence. Furthermore, vitamin D reduced metabolic parameters connected with IR and improved glucose and lipid metabolism. Therefore, our results support the assertion that vitamin D, by reducing oxidative stress and improving of metabolic profile, may decrease IR and related diseases.

Analysis of Association between Vitamin D Deficiency and Insulin Resistance.

Recent evidence revealed extra skeleton activity of vitamin D, including prevention from cardiometabolic diseases and cancer development as well as anti-inflammatory properties. It is worth noting that vitamin D deficiency is very common and may be associated with the pathogenesis of insulin-resistance-related diseases, including obesity and diabetes. This review aims to provide molecular mechanisms showing how vitamin D deficiency may be involved in the insulin resistance formation. The PUBMED database and published reference lists were searched to find studies published between 1980 and 2019. It was identified that molecular action of vitamin D is involved in maintaining the normal resting levels of ROS and Ca2+, not only in pancreatic ß-cells, but also in insulin responsive tissues. Both genomic and non-genomic action of vitamin D is directed towards insulin signaling. Thereby, vitamin D reduces the extent of pathologies associated with insulin resistance such as oxidative stress and inflammation. More recently, it was also shown that vitamin D prevents epigenetic alterations associated with insulin resistance and diabetes. In conclusion, vitamin D deficiency is one of the factors accelerating insulin resistance formation. The results of basic and clinical research support beneficial action of vitamin D in the reduction of insulin resistance and related pathologies.