[Correlation between plasma concentrations of homocysteine and diabetic polyneuropathy evaluated with the Semmes-Weinstein monofilament test in patients with type 2 diabetes mellitus]

Lactobacillus Sps in Reducing the Risk of Diabetes in High-Fat Diet-Induced Diabetic Mice by Modulating the Gut Microbiome and Inhibiting Key Digestive Enzymes Associated with Diabetes

Simple Summary

Type 2 diabetes (T2D) is increasingly spreading across the globe. The disease is linked to a disruption of gut microbiome. Probiotics are essential gut microbiota modulators proven to restore microbiota changes, thereby conferring health to its host. This study aimed to use probiotics (lactobacilli) and their metabolites as natural anti-diabetic therapy through the modulation of gut microbiota and inhibit diabetes-causing enzymes. Lactobacillus-treated high-fat diet mice showed lower blood glucose levels and body weight. Interestingly, our study also proved that the lactobacilli altered gut microbiota composition by suppressing opportunistic bacteria that are highly associated with metabolic diseases. Our findings substantiate the use of probiotics as natural anti-diabetic therapeutics.

Abstract

Obesity caused by a high-fat diet (HFD) affects gut microbiota linked to the risk of type-2 diabetes (T2D). This study evaluates live cells and ethanolic extract (SEL) of Lactobacillus sakei Probio65 and Lactobacillus plantarum Probio-093 as natural anti-diabetic compounds. In-vitro anti-diabetic effects were determined based on the inhibition of α-glucosidase and α-amylase enzymes. The SEL of Probio65 and Probio-093 significantly retarded α-glucosidase and α-amylase enzymes (p < 0.05). Live Probio65 and Probio-093 inhibited α-glucosidase and α-amylase, respectively (p < 0.05). In mice fed with a 45% kcal high-fat diet (HFD), the SEL and live cells of both strains reduced body weight significantly compared to HFD control (p < 0.05). Probio-093 also improved blood glucose level compared to control (p < 0.05). The gut microbiota modulatory effects of lactobacilli on HFD-induced diabetic mice were analyzed with qPCR method. The SEL and live cells of both strains reduced phyla Deferribacteres compared to HFD control (p < 0.05). The SEL and live cells of Probio-093 promoted more Actinobacteria (phyla), Bifidobacterium, and Prevotella (genus) compared to control (p < 0.05). Both strains exerted metabolic-modulatory effects, with strain Probio-093 showing more prominent alteration in gut microbiota, substantiating the role of probiotics in gut microbiome modulations and anti-diabetic effect. Both lactobacilli are potential candidates to lessen obesity-linked T2D.

The relationship between exacerbated diabetic peripheral neuropathy and metformin treatment in type 2 diabetes mellitus

Metformin-treated diabetics (MTD) showed a decrease in cobalamin, a rise in homocysteine, and methylmalonic acid, leading to accentuated diabetic peripheral neuropathy (DPN). This study aimed to determine whether or not metformin is a risk factor for DPN. We compared MTD to non-metformin-treated diabetics (NMTD) clinically using the Toronto Clinical Scoring System (TCSS), laboratory (methylmalonic acid, cobalamin, and homocysteine), and electrophysiological studies. Median homocysteine and methylmalonic acid levels in MTD vs. NMTD were 15.3 vs. 9.6 µmol/l; P < 0.001 and 0.25 vs. 0.13 µmol/l; P = 0.02, respectively with high statistical significance in MTD. There was a significantly lower plasma level of cobalamin in MTD than NMTD. Spearman’s correlation showed a significant negative correlation between cobalamin and increased dose of metformin and a significant positive correlation between TCSS and increased dose of metformin. Logistic regression analysis showed that MTD had significantly longer metformin use duration, higher metformin dose > 2 g, higher TCSS, lower plasma cobalamin, and significant higher homocysteine. Diabetics treated with metformin for prolonged duration and higher doses were associated with lower cobalamin and more severe DPN.

An update on vitamin D and B deficiency in the pathogenesis and treatment of diabetic neuropathy: a narrative review

Diabetic peripheral neuropathy (DPN) is highly prevalent and affects up to 50% of patients with diabetes. Painful neuropathic symptoms may occur in a third of patients with diabetes and is a major cause of sleep disturbance, morbidity and poor quality of life. Effective treatment of DPN remains a major challenge as current therapeutic options have a number of undesirable side effects and only provide a partial response to neuropathic pain. Furthermore, there are a lack of treatments that modulate the natural history of DPN. A growing body of evidence suggests that vitamin B and vitamin D may have analgesic effects and neuroprotective benefits in DPN. This narrative review explores the role of these vitamins in DPN. Given their limited side effects, further mechanistic studies and good quality randomized controlled trials of their putative analgesic ability are required to define the role of vitamin B and D in DPN.

Association between MTHFR variant and diabetic neuropathy

BACKGROUND

Methylene-tetrahydrofolate reductase (MTHFR) gene variant may play an important role in the pathophysiology of diabetes and its complications due to its influence on plasma homocysteine levels and also its effect on scavenging peroxynitrite radicals. Diabetic peripheral neuropathy (DPN) is one of the most common diabetic chronic complications. The aim of this study was to investigate the relationship between diabetic neuropathy and MTHFR gene C677T and 1298A ⁄C polymorphisms.

METHOD

Patients with type 2 diabetes N=248 were enrolled in the study, consisting of patients with neuropathy (N=141) and patients without neuropathy (N=107). MTHFR C677T polymorphism was analyzed using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) of genomic DNA for genotyping of samples. 1298A/C polymorphism was evaluated using ARMS-PCR.

RESULT

There was a significant difference in MTHFR polymorphism between the groups with and without neuropathy.

CONCLUSION

Our results suggest that MTHFR 677 variant confer risk for diabetic neuropathy among Iranian patients with type 2 diabetes.

Serum folate, vitamin B12 levels and diabetic peripheral neuropathy in type 2 diabetes: A meta-analysis

The association between serum folate and vitamin B12 levels and the risk of diabetic peripheral neuropathy (DPN) remains unclear. This meta-analysis included 16 studies of serum folate levels (1190 cases and 1501 controls) and 18 studies of serum vitamin B12 levels (1239 cases and 1562 controls) in patients with type 2 diabetes mellitus (T2DM). Reduced serum levels of folate and vitamin B12 were found in patients with T2DM and DPN compared with patients with T2DM but without DPN; weighted mean difference (WMD) = -1.64 (95% confidence interval [CI] = -2.46, -0.81) and WMD = -70.86 (95% CI = -101.55, -40.17), respectively. A subgroup analysis confirmed these associations in the Chinese population, but not in the Caucasian and mixed populations. In conclusion, these findings support the need for further controlled studies in defined patient populations and the importance of monitoring serum folate and vitamin B12 levels in patients with T2DM.

Diabetic neuropathy is not associated with homocysteine, folate, vitamin B12 levels, and MTHFR C677T mutation in type 2 diabetic outpatients taking metformin

BACKGROUND

Hyperhomocysteinemia and vitamin B12 deficiency may be involved in the development of diabetic peripheral neuropathy (DPN). Metformin therapy may reduce vitamin B12 plasma levels, thus contributing to DPN.

AIM AND METHODS

The purposes of this cross-sectional study were to assess (1) the potential associations of DPN with serum levels of homocysteine (tHcy), B-vitamins, and/or the common methylenetetrahydrofolate reductase (MTHFR) C677T mutation; (2) the influence of chronic treatment with metformin on tHcy and B-vitamins concentrations and, finally, (3) to evaluate whether, by this influence, metformin is a risk factor for DPN in a group of type 2 diabetic outpatients.

RESULTS

Our data showed that fasting tHcy, folate, and vitamin B12 levels and the MTHFR C677T genotype distribution were comparable between subjects with (n = 79, 30 %) and without DPN (n = 184, 70 %). Metformin-treated subjects (n = 124, 47 %) showed significantly lower levels of vitamin B12 (P < 0.001), but the prevalence of DPN was not different when compared to those not treated with this drug (33 vs. 27 %, P = NS). At univariate regression analysis, DPN was associated with age, duration of diabetes, HbA1c, creatinine levels, and the presence of coronary heart disease (CHD), and negatively with HDL-C concentrations (P < 0.05 all), but at multivariate regression analysis, high creatinine levels (P = 0.06), low HDL-C levels (P = 0.013), and a higher prevalence of CHD (P = 0.001) were the only variables independently associated with DPN in this population.

CONCLUSIONS

In conclusion, in these type 2 diabetic outpatients circulating levels of tHcy, folate, and the MTHFR C677T mutation are not associated with DPN, which was predicted by creatinine levels, CHD, and dyslipidemia. Metformin therapy is associated with a mild vitamin B12 level reduction, but not with DPN.

The Effect of Cigarette Smoking on Diabetic Peripheral Neuropathy: A Systematic Review and Meta-Analysis

OBJECTIVE

Studies suggest that smoking may be a risk factor for the development of microvascular complications such as diabetic peripheral neuropathy (DPN). The objective of this study was to assess the relationship between smoking and DPN in persons with type 1 or type 2 diabetes.

RESEARCH DESIGN AND METHODS

A systematic review of the PubMed, Embase, and Cochrane clinical trials databases was conducted for the period from January 1966 to November 2014 for cohort, cross-sectional and case-control studies that assessed the relationship between smoking and DPN. Separate meta-analyses for prospective cohort studies and case-control or cross-sectional studies were performed using random effects models.

RESULTS

Thirty-eight studies (10 prospective cohort and 28 cross-sectional) were included. The prospective cohort studies included 5558 participants without DPN at baseline. During follow-up ranging from 2 to 10 years, 1550 cases of DPN occurred. The pooled unadjusted odds ratio (OR) of developing DPN associated with smoking was 1.26 (95% CI 0.86-1.85; I(2) = 74%; evidence grade: low strength). Stratified analyses of the prospective studies revealed that studies of higher quality and with better levels of adjustment and longer follow-up showed a significant positive association between smoking and DPN, with less heterogeneity. The cross-sectional studies included 27,594 participants. The pooled OR of DPN associated with smoking was 1.42 (95% CI 1.21-1.65; I(2) = 65%; evidence grade: low strength). There was no evidence of publication bias.

CONCLUSIONS

Smoking may be associated with an increased risk of DPN in persons with diabetes. Further studies are needed to test whether this association is causal and whether smoking cessation reduces the risk of DPN in adults with diabetes.

Vitamins and type 2 diabetes mellitus

The present review evaluates the relationship between type 2 diabetes mellitus and individual or combined vitamins. Antioxidant vitamins A, C and E are found decreased in diabetic subjects, possibly due to an increased need to control the excessive oxidative stress produced by abnormalities in glucose metabolism. On the other hand, retinol binding protein exerts a modulating effect, as it has adipokine functions. With respect to the B group vitamins, thiamin, pyridoxine and biotin have been found decreased but the mechanisms are not clear, however supplementation has shown some improvement of the metabolic control in diabetic patients. The absorption of folic acid and vitamin B12 is importantly decreased by the prolongued use of metformin, which is the first choice drug in uncomplicated diabetes, thus these two nutrients have been found deficient in the disease and most probably need to be supplemented regularly. On the other hand, vitamin D is considered a risk factor for the development of diabetes as well as its complications, particularly cardiovascular ones. Although some studies have found an association of vitamin K intake with glucose metabolism further research is needed. Studies on the use of multivitamin supplements have shown unconclusive results. After reviewing the evidence, no real recommendation on the use of vitamin supplements in type 2 diabetes mellitus can be issued, however patients using metformin during prolongued periods may need folic acid and vitamin B12.