Metformin With Either Histamine H2-Receptor Antagonists or Proton Pump Inhibitors: A Polypharmacy Recipe for Neuropathy via Vitamin B12 Depletion

Mapping Endothelial-Macrophage Interactions in Diabetic Vasculature: Role of TREM2 in Vascular Inflammation and Ischemic Response

Vasculopathies occur 15 years earlier in individuals with diabetes mellitus (DM) as compared to those without, but the underlying mechanisms driving diabetic vasculopathy remain incompletely understood. Endothelial cells (ECs) and macrophages (MΦ) are critical players in vascular wall and their crosstalk is crucial in diabetic vasculopathy. In diabetes, EC activation enables monocyte recruitment, which transmigrate into the intima and differentiate into macrophages (MΦ). Beyond this established model of diapedesis, EC-MΦ interplay is highly intricate and heterogenous. To capture these highly context dependent EC-MΦ interactions, we leveraged single-cell (sc)RNA-seq in conjunction with spatial transcriptome (ST)-seq profiling to analyze human mesenteric arteries from non-diabetic (ND) and type 2 diabetic (T2D) donors. We provide in this study a transcriptomic map encompassing major arterial vascular cells, e.g., EC, mononuclear phagocyte (MP), and T cells, and their interactions associated with human T2D. Furthermore, we identified Triggering Receptor Expressed on Myeloid Cells 2 ( TREM2) as a top T2D-induced gene in MP, with concomitant increase of TREM2 ligands in ECs. TREM2 induction was confirmed in mouse models of T2D and monocyte/MΦ subjected to DM-mimicking stimuli. Perturbing TREM2 with either an antibody or silencing RNA in MPs led to decreased pro-inflammatory responses in MPs and ECs and increased EC migration in vitro . In a mouse model of diabetes, TREM2 expression and its interaction with ECs are increased in the ischemic, as compared to non-ischemic muscles. Importantly, neutralization of TREM2 using a neutralizing antibody enhanced ischemic recovery and flow reperfusion in the diabetic mice, suggesting a role of TREM2 in promoting diabetic PAD. Finally, we verified that both TREM2 expression and the TREM2-EC-interaction are increased in human patients with DM-PAD. Collectively, our study presents the first atlas of human diabetic vessels with a focus on EC-MP interactions. Exemplified by TREM2, our study provides valuable insights into EC-MΦ interactions, key processes contributing to diabetic vasculopathies and the potential of targeting these interactions for therapeutic development.

Association between Acid-Lowering Agents, Metformin, and Vitamin B12 among Boston-Area Puerto Ricans

BACKGROUND

Vitamin B12 involves several physiological functions, and malabsorption is reported with medication use.

OBJECTIVES

Studies have reported an inverse association between the use of metformin or acid-lowering agents (ALAs), such as proton pump inhibitors, histamine 2 receptor antagonists, and blood vitamin B12 concentration, because of malabsorption. The concomitant use of these medications is underreported. We sought to examine these associations in a cohort of Boston-area Puerto Rican adults.

METHODS

This analysis was conducted within the Boston Puerto Rican Health Study (BPRHS), an ongoing longitudinal cohort that enrolled 1499 Puerto Rican adults aged 45-75 y at baseline. Our study comprised 1428, 1155, and 782 participants at baseline, wave2 (2.2 y from baseline), and wave3 (6.2 y from baseline), respectively. Covariate-adjusted linear and logistic regression was used to examine the association between baseline medication use and vitamin B12 concentration or deficiency (vitamin B12 <148 pmol/L or methylmalonic acid >271 nmol/L), and long-term medication use (continuous use for ∼6.2 y) and wave3 vitamin B12 concentration and deficiency. Sensitivity analyses were done to examine these associations in vitamin B12 supplement users.

RESULTS

At baseline, we observed an association between metformin use (β = -0.069; P = 0.03) and concomitant ALA and metformin use (β = -0.112; P = 0.02) and vitamin B12 concentration, but not a deficiency. We did not observe associations between ALA, proton pump inhibitors, or histamine 2 receptor antagonists, individually, with vitamin B12 concentration or deficiency.

CONCLUSIONS

These results suggest an inverse relationship between metformin, concomitant ALA, metformin use, and serum vitamin B12 concentration.

Adverse Effects of Medications on Micronutrient Status: From Evidence to Guidelines

Recent dietary reference intake workshops focusing on nutrient requirements in chronic disease populations have called attention to the potential adverse effects of chronic medication use on micronutrient status. Although this topic is mostly ill defined in the literature, several noteworthy drug-nutrient interactions (DNIs) are of clinical and public health significance. The purpose of this narrative review is to showcase classic examples of DNIs and their impact on micronutrient status, including those related to antidiabetic, anticoagulant, antihypertensive, antirheumatic, and gastric acid-suppressing medications. Purported DNIs related to other drug families, while relevant and worthy of discussion, are not included. Unlike previous publications, this review is primarily focused on DNIs that have sufficient evidence supporting their inclusion in US Food and Drug Administration labeling materials and/or professional guidelines. While the evidence is compelling, more high-quality research is needed to establish clear and quantitative relationships between chronic medication use and micronutrient status. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Interaction between Omeprazole and Gliclazide in Relation to CYP2C19 Phenotype

The antidiabetic drug gliclazide is partly metabolized by CYP2C19, the main enzyme involved in omeprazole metabolism. The aim of the study was to explore the interaction between omeprazole and gliclazide in relation to CYP2C19 phenotype using physiologically based pharmacokinetic (PBPK) modeling approach. Developed PBPK models were verified using in vivo pharmacokinetic profiles obtained from a clinical trial on omeprazole-gliclazide interaction in healthy volunteers, CYP2C19 normal/rapid/ultrarapid metabolizers (NM/RM/UM). In addition, the association of omeprazole cotreatment with gliclazide-induced hypoglycemia was explored in 267 patients with type 2 diabetes (T2D) from the GoDARTS cohort, Scotland. The PBPK simulations predicted 1.4–1.6-fold higher gliclazide area under the curve (AUC) after 5-day treatment with 20 mg omeprazole in all CYP2C19 phenotype groups except in poor metabolizers. The predicted gliclazide AUC increased 2.1 and 2.5-fold in intermediate metabolizers, and 2.6- and 3.8-fold in NM/RM/UM group, after simulated 20-day dosing with 40 mg omeprazole once and twice daily, respectively. The predicted results were corroborated by findings in patients with T2D which demonstrated 3.3-fold higher odds of severe gliclazide-induced hypoglycemia in NM/RM/UM patients concomitantly treated with omeprazole. Our results indicate that omeprazole may increase exposure to gliclazide and thus increase the risk of gliclazide-associated hypoglycemia in the majority of patients.

Anti-diabetic effects of blue honeyberry on high-fed-diet-induced type II diabetic mouse

BACKGROUND/OBJECTIVE

The blue honeysuckle berry (Lonicera caerulea var. edulis L.) is a small deciduous shrub belonging to the Caprifoliaceae family that is native to Russia, China, Japan, and Korea. The berry of this shrub is edible, sweet and juicy and is commonly known as the blue honeyberry (BHB). This study examined the anti-diabetic potential of BHB on high-fat-diet-induced mild diabetic mice. The hypoglycemic, and nephroprotective effects of the 12-week oral administration of blue honeyberry extract were analyzed.

MATERIALS/METHODS

The hypoglycemic effects were based on the observed changes in insulin, blood glucose, and glycated hemoglobin (HbA1c). Furthermore, the changes in the weight of the pancreas, including its histopathology and immunohistochemical investigation were also performed. Moreover, the nephroprotective effects were analyzed by observing the changes in kidney weight, its histopathology, blood urea nitrogen (BUN), and serum creatinine levels.

RESULTS

The results showed that the high-fat diet (HFD)-induced control mice showed a noticeable increase in blood glucose, insulin, HbA1c, BUN, and creatinine levels. Furthermore, growth was observed in lipid droplet deposition related to the degenerative lesions in the vacuolated renal tubules with the evident enlargement and hyperplasia of the pancreatic islets. In addition, in the endocrine pancreas, there was an increase in the insulin-and glucagon-producing cells, as well as in the insulin/glucagon cell ratios. On the other hand, compared to the HFD-treated mice group, all these diabetic and related complications were ameliorated significantly in a dose-dependent manner after 84 days of the continuous oral administration of BHBe at 400, 200 and 100 mg/kg, and a dramatic resettlement in the hepatic glucose-regulating enzyme activities was observed.

CONCLUSIONS

By assessing the key parameters for T2DM, the present study showed that the BHBe could act as a potential herbal agent to cure diabetes (type II) and associated ailments in HFD-induced mice.

Vitamin B12 Deficiency Induces Imbalance in Melanocytes Homeostasis-A Cellular Basis of Hypocobalaminemia Pigmentary Manifestations

Vitamin B₁₂ deficiency causes significant changes in cellular metabolism leading to various clinical symptoms, such as hematological, psychiatric, and neurological disorders. We hypothesize that skin pigmentation disorders may be a diagnostically important manifestation of vitamin B₁₂ deficiency, however the cellular and molecular mechanisms underlying these effects remain unknown. The aim of this study was to examine the effect of vitamin B₁₂ deficiency on melanocytes homeostasis. Hypocobalaminemia in vitro model was developed by treating epidermal melanocytes with synthesized vitamin B₁₂ antagonist—hydroxycobalamin(c-lactam). The cells were examined using immunoenzymatic, spectrophotometric, and fluorimetric assays as well as image cytometry. Significant melanogenesis stimulation—the increase of relative melanin content and tyrosinase activity up to 131% and 135%, respectively—has been indicated. Cobalamin-deficient cells displayed the elevation (by 120%) in reactive oxygen species level. Moreover, the redox status imbalance was stated. The study provided a scientific evidence for melanocytes homeostasis disturbance under hypocobalaminemia, thus indicating a significant element of the hyperpigmentation mechanism due to vitamin B₁₂ deficiency. Furthermore, the implication between pigmentary and hematological and/or neuropsychiatric symptoms in cobalamin-deficient patients may be an important issue.

Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications

There is clear evidence that proton-pump inhibitors (PPIs), H2-receptor antagonists (H2RAs), and metformin can reduce serum vitamin B-12 concentrations by inhibiting the absorption of the vitamin. However, it is unclear if the effects of these drugs on serum vitamin B-12 are associated with increased risk of biochemical or functional deficiency (as is indicated by elevated blood concentrations of homocysteine and methylmalonic acid) or clinical deficiency (including megaloblastic anemia and neurologic disorders such as peripheral neuropathy and cognitive dysfunction). This review provides an overview of vitamin B-12 absorption and biochemistry and the mechanisms by which PPIs, H2RAs, and metformin affect these functions. It also summarizes the literature relating the use of these drugs to the risk of vitamin B-12 deficiency. Also discussed is that strategies for assessing vitamin B-12 status and diagnosing vitamin B-12 deficiency have evolved in recent years beyond solely measuring serum total vitamin B-12. Multiple analyte testing, a strategy in which ≥2 of 4 biomarkers of vitamin B-12 status-serum total vitamin B-12, holotranscobalamin, homocysteine, and methylmalonic acid-are measured, increases sensitivity and specificity for diagnosing vitamin B-12 deficiency. It is concluded that randomized controlled trials are now needed that use the strategy of multiple analyte testing to determine if PPIs, H2RAs, and metformin do indeed increase the risk of vitamin B-12 deficiency. Until these studies are conducted, a reasonable recommendation for physicians and their patients who are taking these drugs is to monitor vitamin B-12 status and to provide vitamin B-12 supplements if altered blood biomarkers or clinical signs consistent with low or deficient vitamin B-12 status develop.

Long-term treatment with metformin in type 2 diabetes and methylmalonic acid: Post hoc analysis of a randomized controlled 4.3year trial

AIMS

Metformin treatment is associated with a decrease of serum vitamin B12, but whether this reflects tissue B12 deficiency is controversial. We studied the effects of metformin on serum levels of methylmalonic acid (MMA), a biomarker for tissue B12 deficiency, and on onset or progression of neuropathy.

METHODS

In the HOME trial, 390 insulin-treated patients with type 2 diabetes were treated with metformin or placebo for 52months. In a post hoc analysis, we analyzed the association between metformin, MMA and a validated Neuropathy Score (NPS).

RESULTS

Metformin vs placebo increased MMA at the end of the study (95%CI: 0.019 to 0.055, p=0.001). Mediation analysis showed that the effect of metformin on the NPS consisted of a beneficial effect through lowering HbA1c (-0.020 per gram year) and an adverse effect through increasing MMA (0.042 per gram year), resulting in a non-significant net effect (0.032 per gram year, 95% CI: -0.121 to 0.182, p=0.34).

CONCLUSION

Metformin not only reduces serum levels of B12, but also progressively increases serum MMA. The increase of MMA in metformin users was associated with significant worsening of the NPS. These results provide further support that metformin-related B12 deficiency is clinically relevant. Monitoring of B12 in users of metformin should be considered.

THE RISK OF COBALAMIN DEFICIENCY SYMPTOMS RELATED TO LONG-TERM METFORMIN USE IN T2DM PATIENTS

Background

Metformin is the first-line oral antidiabetic agent used in the treatment of diabetes mellitus. One of the adverse reactions of the long term use of metformin is cobalamin malabsorption. Clinical and laboratory findings are important in the diagnosis of cobalamin deficiency.

Objective

This study aimed to evaluate the risk of cobalamin deficiency symptoms related to long-term use of metformin in type 2 diabetes mellitus patients at Pasar Rebo General Hospital in Jakarta.

Setting

This quantitative, observational study with retrospective cohort design was conducted in outpatient department Pasar Rebo General Hospital November 2015 until January 2016.

Methods

200 subjects were recruited and divided into two groups, patients who had been taking metformin for 1-3 years and patients who had been taking metformin for more than 3 years. Each patient was assessed for the presence of cobalamin deficiency symptoms.

Main outcome measure

Cobalamin deficiency symptoms evaluated were symptoms of neuropathy (measured by DN4 questionnaire) and hematologic abnormalities associated to cobalamin deficiency, i.e. macrocytic erythrocyte, hypersegmented neutrophils, and giant bands.

Results

There are significant differences in the proportions of neuropathy symptoms (RR 2.36, 95%, p=0.000) and hematologic abnormalities (RR 1.5, 95%, p=0.007) between the two groups.

Conclusions

Long-term use of metformin (≥3 years) may increase the risk of cobalamin deficiency symptoms in type 2 diabetes mellitus patients.

Drug Interactions of Metformin Involving Drug Transporter Proteins

Metformin is a most widely used medication all around the world to treat Type 2 diabetes mellitus. It is also found to be effective against various conditions including, Prediabetes, Gestational diabetes mellitus (GDM), Polycystic Ovarian Syndrome (PCOS), Obesity, Cancer, etc. It is a cationic drug and it depends Organic Cation Transporters (OCTs) and Multidrug and Toxin Extruders (MATEs) mostly for its pharmacokinetics movement. The probability of drug interaction increases with the number of concomitant medications. This article focuses the drug interactions of metformin and most of them are linked to the inhibition of OCTs and MATEs leading to increased plasma metformin concentrations and subsequent elevation of risk of Metformin Associated Lactic Acidosis (MALA). By identifying the drugs inhibiting OCTs and MATEs, the healthcare professionals can predict the drug interactions of metformin.

Vitamin B12 deficiency is associated with cardiovascular autonomic neuropathy in patients with type 2 diabetes

AIMS

Vitamin B12 deficiency could be associated with cardiovascular autonomic neuropathy (CAN) in diabetes patients. We aim to investigate the association between serum levels of vitamin B12 and CAN in type 2 diabetes patients.

METHODS

469 ambulatory type 2 diabetes patients (mean diabetes duration 10.0years (IQR 5.0;17.0), mean age 59.0years (SD 11.6), 63% men, mean B12 289.0pmol/l (IQR 217;390)) were screened for CAN using three cardiovascular reflex tests, five minute resting heart rate (5min RHR) and heart rate variability indices.

RESULTS

Serum levels of vitamin B12 were significantly lower in patients treated with metformin and/or proton pump inhibitors (PPIs) compared with patients not treated (p<0.001). A 25pmol/l higher level of vitamin B12 was associated with an odds ratio of the CAN diagnosis of 0.94 (95% CI 0.88; 1.00, p=0.034), an increase in E/I-ratio of 0.21% (95% CI 0.01; 0.43, p=0.038), and a decrease in 5min RHR of 0.25 beats per minute (95% CI -0.47; -0.03, p=0.025).

CONCLUSION

Vitamin B12 may be inversely associated with CAN in patients with type 2 diabetes. Confirmatory studies investigating a causal role of vitamin B12 for the development of diabetic CAN are warranted.

Metformin: From Research to Clinical Practice

Metformin is the recommended first-line oral glucose-lowering drug initiated to control hyperglycemia in type 2 diabetes mellitus. It acts in the liver, small intestines, and skeletal muscles with its major effect on decreasing hepatic gluconeogenesis. It is safe, inexpensive, and weight neutral and can be associated with weight loss. It can reduce microvascular complication risk and its use is associated with a lower cardiovascular mortality compared with sulfonylurea therapy. It is also used to delay the onset of type 2 diabetes mellitus, in treating gestational diabetes, and in women with polycystic ovary syndrome.

Endoscopic hemostat combined with different doses of proton pump inhibitor for management of acute non-varicose upper gastrointestinal bleeding in elderly patients

AIM: To compare the clinical effects of endoscopic hemostat combined with different doses of proton pump inhibitor (PPI) in the treatment of elderly patients with acute non-varicose upper gastrointestinal bleeding.

METHODS: Two hundred and six elderly patients with acute non-varicose upper gastrointestinal bleeding treated from January 2009 to December 2014 were divided and equally into either a high- or a conventional-dose PPI group. Patients in the conventional-dose group were given a conventional dose of PPI, while the high-dose group was given a high dose. Both groups of patients received endoscopic hemostasis. The duration of vomiting and melena, average length of hospital stay, volume of blood transfusion, re-bleeding and clinical efficacy were compared for the two groups.

RESULTS: The duration of vomiting and melena, average length of hospital stay and volume of blood transfusion were significantly lower in the high-dose group than in the conventional-dose group (1.12 d ± 0.38 d vs 3.47 d ± 0.53 d, 3.22 d ± 0.46 d vs 5.35 d ± 1.11 d, 7.17 d ± 1.32 d vs 10.57 d ± 1.79 d, 440.30 mL ± 86.65 mL vs 764.50 mL ± 125.36 mL, P < 0.05). The time to hemostasis, rebleeding rate, and rate of conversion to open surgery were significantly lower in the high-dose group than in the conventional-dose group (1.62 h ± 0.69 h vs 3.49 h ± 1.03 h, 3.88% vs 13.59%, 0.97% vs 5.83%, P < 0.05).

CONCLUSION: Endoscopic hemostat combined with high-dose PPI for acute non-varicose upper gastrointestinal bleeding is better in shortening the duration of vomiting and melena and reducing hospitalization time and rebleeding.