Association of biochemical B₁₂ deficiency with metformin therapy and vitamin B₁₂ supplements: the National Health and Nutrition Examination Survey, 1999-2006

Antinuclear antibodies and mortality in the National Health and Nutrition Examination Survey (1999-2004)

OBJECTIVE

Recent studies suggest antinuclear antibodies (ANA) may be related to mortality risk, but evidence is sparse and inconclusive. Thus, we investigated ANA associations with all-cause and cause-specific mortality in U.S. adults.

METHODS

Our sample included 3357 adults (ages ≥20 years) from the 1999-2004 National Health and Nutrition Examination Survey with ANA measurements (1:80 dilution) and mortality data through 2011 (median follow-up: 9.4 years). We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) via weighted Cox regression to assess ANA associations with mortality from all causes, cardiovascular disease (CVD), and cancer. Models adjusted for age, sex, race/ethnicity, education, and obesity. Analyses examined mortality in the full sample and in subgroups based on self-reported histories of CVD and cancer, both overall and stratified by sex and age at enrollment.

RESULTS

Overall, ANA were not strongly associated with death from all causes (HR: 1.13; CI: 0.79, 1.60), from CVD (HR: 1.60; CI: 0.80, 3.20), or from cancer (HR: 1.58; CI: 0.75, 3.33), though all three HR estimates exceeded 1. In the subgroup with a history of cancer, ANA were associated with elevated all-cause mortality in men (HR: 2.28; CI: 1.01, 5.14) and in participants who enrolled at age ≥75 years (HR: 1.99; CI: 1.04, 3.80).

CONCLUSION

These findings suggest that ANA are not strongly associated with mortality in the general population. Longitudinal studies with repeated assessments are needed to understand the temporal relationship between ANA, aging-associated diseases, and mortality.

Effects of metformin exposure on neurodegenerative diseases in elderly patients with type 2 diabetes mellitus

Epidemiological evidence reveals that patients with type 2 diabetes mellitus (T2DM) have an increased risk of neurodegenerative diseases (NDs), including dementia and Parkinson's disease (PD). The effects of metformin exposure on dementia and PD risk in patients with T2DM are unknown. We evaluated the effects of metformin exposure on the risk of dementia and PD in patients with T2DM. We performed a cohort study by using Taiwan's National Health Insurance Research Database. We recruited 4651 patients in the metformin cohort and a comparable number of nonmetformin controls by using propensity score matching. Multivariate Cox proportional hazards regression was used to estimate the effects of metformin on the risk of dementia and PD after adjustment for several confounding factors. During the 12-year follow-up, the metformin cohort exhibited a higher risk of PD than the nonmetformin cohort (hazard ratio [HR]: 2.27, 95% confidence interval [CI]=1.68-3.07). The metformin cohort had an increased risk of all-cause dementia (HR: 1.66, 95% CI=1.35-2.04). Moreover, metformin exposure increased the risk of Alzheimer's disease (HR: 2.13, 95% CI=1.20-3.79) and vascular dementia (HR: 2.30, 95% CI=1.25-4.22). The effects of exposure duration and dosage on dementia and PD occurrence were also observed. Long-term metformin exposure in patients with T2DM may lead to the development of NDs, including dementia and PD. Additional large-scale, prospective controlled trials are required to confirm the observed association in patients with T2DM.

Comparative evaluation of probiotics effects on plasma glucose, lipid, and insulin levels in streptozotocin-induced diabetic rats

BACKGROUND

Diabetes is a chronic disorder caused by the relative decrease in insulin production from the pancreas, tissue resistance to insulin, or both. Daily consumption of probiotics, particularly Lactobacilli, has been proposed as a new strategy for prevention or control of diabetes.

METHODS

In the current study, the effects of various probiotics including Lactobacillus reuteri (L reuteri), Lactobacillus crispatus (L crispatus), and Bacillus subtilis on the levels of blood glucose, lipid, and insulin as well as haemoglobin A_1c (HbA_1c ) were investigated in rat models of streptozotocin (STZ)-induced diabetes and compared with metformin. In addition, GLUT-4 and PPAR-γ transcript levels have been analysed in adipose tissues.

RESULTS

A significant decrease in plasma glucose and HbA_1c levels and a dramatic increase in insulin levels have been detected after consumption of probiotics. Furthermore, lipid profiles have been improved. The expression of Glut-4 and Ppar-γ genes in adipose tissues also increased after treatment period.

CONCLUSION

The results of this experiment showed that daily consumption of probiotics can be effective in control of STZ-induced diabetes and its complications.

Characteristics of Vitamin B12 Deficiency in Patients With Plasma Cell Disorders

BACKGROUND

Although increased rates of vitamin B12 deficiency have been reported in patients with plasma cell dyscrasias (PCDs), no mechanism has been identified. Excess free light chains (FLCs) could disrupt the renal proximal tubule receptors where B12 is reabsorbed. We sought to characterize the relationship between B12 deficiency and PCDs. We hypothesized that rates of B12 deficiency would be highest in patients with PCDs with high FLC burdens.

METHODS

We reviewed the electronic medical records of 501 patients who met inclusion criteria (diagnosed PCD with documented serum B12 and FLC levels) to obtain clinical data recorded prior to patients' lowest B12 levels.

RESULTS

Overall, 20.0% of patients had low vitamin B12. There was an expected negative correlation between estimated glomular filtration rate and FLC (r_s = -0.317; P < .001). However, low B12 levels were more prevalent in patients with preserved renal function (P = .047). Low B12 was associated with lower mean corpuscular volume (P = .037).

CONCLUSION

Higher FLC burden was associated with poor kidney function but not with low B12. Low B12 was seen more commonly in patients with preserved kidney function. Mean corpuscular volume was statistically but not clinically different between patients with low and normal B12 and, therefore, may not be a reliable indicator of B12 deficiency in PCDs. Prospective studies should compare B12 metabolites with FLC levels. Detection of B12 deficiency among patients with PCDs remains important to reduce neurologic dysfunction and cytopenias, sequelae common to B12 deficiency and PCDs.

Metformin Use and Vitamin B12 Deficiency: Untangling the Association

BACKGROUND

Current evidence linking vitamin B12 deficiency with metformin use is inconsistent. Hence, there is uncertainty regarding the diagnostic approach in this scenario. Furthermore, this possible association has not been studied in the complete spectrum of patients with diabetes.

MATERIALS AND METHODS

We conducted a cross-sectional, controlled study with the objective of assessing differences in serum vitamin B12 levels among patients with and without diabetes with different metformin-treatment regimens. A total of 150 participants were recruited: patients with diabetes (group 1: metformin alone ≥850mg/day, group 2: patients with type 2 diabetes naive to treatment and group 3: metformin ≥850mg/day, in addition to any other oral glucose lowering agent or insulin, or both) and without diabetes (group 4: polycystic ovary syndrome or group 5: healthy individuals). Serum vitamin B12, folate levels and complete blood counts were obtained for the entire population. Methylmalonic acid and homocysteine were obtained for patients when vitamin B12 levels were found to be borderline or low.

RESULTS

When patients with or without diabetes were compared, no significant difference was found in relation to their vitamin B12 levels (517.62 versus 433.83; P = 0.072). No difference in vitamin B12 levels was found among participants with metformin use and metformin naive participants (503.4 versus 462.3; P = 0.380).

CONCLUSIONS

Irrespective of metformin use, no significant difference in the serum levels of vitamin B12 was observed, both in patients with and without diabetes. In the light of the body of evidence and the results of this study, a universal recommendation for vitamin B12 deficiency screening cannot be made.

METFORMIN: NONGLYCEMIC EFFECTS AND POTENTIAL NOVEL INDICATIONS

OBJECTIVE

Metformin is the most commonly prescribed drug for the treatment of type 2 diabetes because of its apparent robust effects in reducing cardiovascular risk. This review examines the current literature regarding the nonglycemic effects and potential novel indications for metformin.

METHODS

Review of the literature, with a focus on metformin use in Stage 3 chronic kidney disease (CKD-3) and heart failure (HF).

RESULTS

The United Kingdom Prospective Diabetes Study suggests that metformin reduces the risk of myocardial infarction, and more recent retrospective studies have shown an association between metformin use and a reduction in stroke, atrial fibrillation and all-cause mortality. The mechanism(s) explaining these putative benefits are not clear but may involve decreased energy intake (with attendant weight loss), improvement in lipids, and lowering of blood pressure; a literature review suggests that metformin lowers blood pressure when it is elevated, but not when it is normal. Metformin appears to be safe when given to patients with CKD-3. In addition, there is evidence that individuals with CKD-3, who are at increased cardiovascular risk, stand to benefit from metformin therapy. Lactic acidosis is an extremely remote and probably avoidable risk; measurement of plasma metformin levels and more frequent monitoring of renal function may be useful in selected patients with CKD-3 who are treated with metformin. Finally, there is evidence that metformin is safe in patients with HF; metformin therapy is associated with a reduction in newly incident HF and in HF mortality.

CONCLUSION

Metformin has a dominant position in the treatment of type 2 diabetes that is deserved due to its favorable and robust effects on cardiovascular risk.

ABBREVIATIONS

AMP = adenosine monophosphate BP = blood pressure CKD = chronic kidney disease CKD-3 = Stage 3 CKD eGFR = estimated glomerular filtration rate HDL = high-density lipoprotein HF = heart failure MAP = mean arterial pressure mVO2 = myocardial oxygen consumption T2DM = type 2 diabetes mellitus UKPDS = United Kingdom Prospective Diabetes Study.

Serum Vitamin B12 Levels in Type 2 Diabetes Patients on Metformin Compared to those Never on Metformin: A Cross-sectional Study

CONTEXT

There are limited data about the effect of metformin use on serum Vitamin B12 levels in type 2 diabetes patients from India.

AIMS

We studied serum Vitamin B12 levels in patients with type 2 diabetes mellitus who were receiving metformin and compared them to those never treated with metformin.

SUBJECTS AND METHODS

A total of 183 patients ("metformin" group 121, "no metformin" group 63) of type 2 diabetes from the endocrinology clinic of a tertiary care center in North India were studied. Serum Vitamin B12 levels were measured in all patients. Diabetic neuropathy symptom score (DNS) and diabetic neuropathy examination score (DNE) were used to assess peripheral neuropathy while hemoglobin and mean corpuscular volume (MCV) were used to assess anemia.

RESULTS

The serum Vitamin B12 levels were 267.7 ± 194.4 pmol/l in metformin group and 275.1 ± 197.2 pmol/l in the no metformin group (P = 0.78). When adjusted for duration of diabetes, metformin use was associated with a 87.7 ± 37.7 pmol/l (95% confidence interval [CI], -162.1--3.3, P = 0.02) lower serum Vitamin B12 levels. No significant increase in the prevalence of neuropathy (DNS and DNE scores), anemia, or MCV was found in the Vitamin B12 deficient patients (levels <150 pmol/l) as compared to patients with normal Vitamin B12. However, serum Vitamin B12 levels for the entire cohort were higher by 12.2 ± 3.0 pmol/l (95% CI 6.4-18.0, P < 0.001) for every 1 year increase in the duration of diabetes.

CONCLUSIONS

Metformin use was associated with a lower serum Vitamin B12 levels when adjusted for duration of diabetes. Increasing duration of diabetes was associated with higher serum Vitamin B12 levels.

Effects of metformin versus placebo on vitamin B12 metabolism in non-diabetic breast cancer patients in CCTG MA.32

BACKGROUND

Metformin is associated with low levels of vitamin B12 (VitB12) in patients with diabetes. The CCTG/MA.32 trial investigates the effects of metformin vs placebo on breast cancer (BC) outcomes in non-diabetic high-risk BC patients. We analyzed VitB12 at baseline and after 6 months of metformin (versus placebo) in the first 492 patients with paired blood samples.

METHODS

VitB12 was analyzed centrally in baseline and 6-month fasting plasma. Levels <181 pmol/L were considered deficient, 181-221 pmol/L borderline, and ≥222 pmol/L sufficient. Methylmalonic acid (MMA) and homocysteine (HC) were assayed in those with VitB12 levels <222 pmol/L. Statistical analyses used Spearman's rank correlation coefficients and Wilcoxon signed-rank test for continuous variables and Chi-square test for categorical variables.

RESULTS

237 patients received metformin and 255 received placebo; median (inter quartile range) baseline VitB12 levels were 390 (290, 552) and 370 (290, 552) pmol/L in the metformin and placebo arms, respectively (p = 0.97). At 6 months, the median levels were 320 (244, 419) in the metformin versus 380 (286, 546) pmol/L in the placebo arm (p = 0.0001). At baseline, 15 patients (11 metformin and 4 placebo) had VitB12 <181 pmol/L, and at 6 months, 18 patients (15 metformin and 3 placebo) (p = 0.004). Median hemoglobin was similar at baseline, metformin, 130 g/L (124-137), and placebo arms, 131 g/L (124-137) (p = 0.38), and at 6 months, metformin, 131 g/L (91-162), and 131 g/L (106-169) in placebo group (p = 0.11). Of the 74 subjects with vitamin B12 <222 pmol/L at either time point (45 metformin, 29 placebo), at baseline MMA was normal in all patients and two had elevated HC (>15μmol/L). At 6 months, one patient (metformin) had MMA >0.4μmol/L and 3 (2 metformin, 1 placebo) had HC > 15μmol/L.

CONCLUSIONS

There was an increased rate of biochemical VitB12 deficiency after 6 months of metformin; this was not associated with anemia. Further research will investigate VitB12 levels in all subjects at baseline and at 6 and 60 months.

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.

Perspectives on Peripheral Neuropathy as a Consequence of Metformin-Induced Vitamin B12 Deficiency in T2DM

Peripheral neuropathy (PN) is a primary complication of type 2 diabetes mellitus (T2DM) and a direct manifestation of vitamin B12 deficiency. Examining the effects of metformin use on PN status became imperative following clinical studies that showed the vitamin B12-lowering effect of the medication. The complexity of the topic and the inconsistency of the results warrant consideration of topic-specific perspectives for better understanding of the available evidence and more appropriate design of future studies.

Prevalence of vitamin B12 deficiency in type 2 diabetic patients using metformin: a cross-sectional study

CONTEXT AND OBJECTIVE:

The prevalence of vitamin B12 deficiency varies from 5.8% to 30% among patients undergoing long-term treatment with metformin. Because of the paucity of data on Brazilian patients, this study aimed to determine the frequency of B12 deficiency and related factors among Brazilian patients with type 2 diabetes mellitus (T2DM) using metformin.

DESIGN AND SETTING:

Cross-sectional study at a public university hospital.

METHODS:

Patients with T2DM and a control group of non-diabetics were included. Serum B12 levels were measured and biochemical B12 deficiency was defined as serum levels < 180 pg/ml. Associations between B12 deficiency and age, duration of T2DM, duration of use and dosage of metformin, and use of proton pump inhibitors (PPIs) or histamine H2 antagonists were determined.

RESULTS:

231 T2DM patients using metformin (T2DM-met) and 231 controls were included. No difference in the frequency of PPI or H2-antagonist use was seen between the groups. B12 deficiency was more frequent in the T2DM-met group (22.5% versus 7.4%) and this difference persisted after excluding PPI/H2-antagonist users (17.9% versus 5.6%). The factors that interfered with serum B12 levels were PPI/H2-antagonist use and duration of metformin use ≥ 10 years. Use of PPI/H2-antagonists was associated with B12 deficiency, with an odds ratio of 2.60 (95% confidence interval, 1.34-5.04).

CONCLUSIONS:

Among T2DM patients, treatment with metformin and concomitant use of PPI/H2-antagonists are associated with a higher chance of developing B12 deficiency than among non-diabetics.

Vitamin B12 deficiency in metformin-treated type-2 diabetes patients, prevalence and association with peripheral neuropathy

Background

The association between long-term metformin use and low vitamin B12 levels has been proven. However, the prevalence estimates of metformin-induced vitamin B12 deficiency showed considerable variation among the studies. The potential of the deficiency to cause or worsen peripheral neuropathy in type-2 diabetes mellitus (T2DM) patients has been investigated with conflicting results. The aim of the study was to investigate: 1) the prevalence of vitamin B12 deficiency in T2DM patients on metformin; 2) the association between vitamin B12 and peripheral neuropathy; 3) and the risk factors for vitamin B12 deficiency in these patients.

Methods

In this cross-sectional study, consecutive metformin-treated T2DM patients attending diabetes clinics of two public hospitals in South Africa were approached for participation. Participation included measuring vitamin B12 levels and assessing peripheral neuropathy using Neuropathy Total Symptom Score-6 (NTSS-6) questionnaire. The prevalence of vitamin B12 deficiency (defined by concentrations <150 pmol/L) was determined. Those with NTSS-6 scores >6 were considered to have peripheral neuropathy. The relationship between vitamin B12 and peripheral neuropathy was investigated when the two variables were in the binary and continuous forms. Multiple logistic regression was used to determine risk factors for vitamin B12 deficiency.

Results

Among 121 participants, the prevalence of vitamin B12 deficiency was 28.1 %. There was no difference in presence of neuropathy between those with normal and deficient vitamin levels (36.8 % vs. 32.3 %, P = 0.209). Vitamin B12 levels and NTSS-6 scores were not correlated (Spearman’s rho =0.056, P = 0.54). HbA1c (mmol/mol) (OR = 0.97, 95 % CI: 0.95 to 0.99, P = 0.003) and black race (OR = 0.34, 95 % CI: 0.13 to 0.92, P = 0.033) were risk factors significantly associated with vitamin B12 deficiency. Metformin daily dose (gram) showed borderline significance (OR = 1.96, 95 % CI: 0.99 to 3.88, P = 0.053).

Conclusions

Close to third of metformin-treated T2DM patients had vitamin B12 deficiency. The deficiency was not associated with peripheral neuropathy. Black race was a protective factor for vitamin B12 deficiency.

Study of Vitamin B12 deficiency and peripheral neuropathy in metformin-treated early Type 2 diabetes mellitus

BACKGROUND

Long-term therapy with metformin was shown to decrease the Vitamin B₁₂ level and manifested as peripheral neuropathy.

AIM

The aim of this study is to define the prevalence of Vitamin B₁₂ deficiency in early Type 2 diabetic patients (duration ≤5 years or drug treatment ≤3 years) and the relationship among metformin exposure and levels of cobalamin (Cbl), folic acid, and homocysteine (Hcy) with severity of peripheral neuropathy.

METHODOLOGY

This is a cross-sectional study involving randomly selected ninety patients (male 56, female 34) between age groups of 35 and 70 years, comparing those who had received >6 months of metformin (Group A) (n = 35) with those without metformin (Group B) (n = 35) and patients taking metformin with other oral hypoglycemic agent (Group C) (n = 20). Comparisons were made clinically, biochemically (serum Cbl, fasting Hcy, and folic acid), and with electrophysiological measures (nerve conduction studies of all four limbs). Comorbidities contributing to neuropathy were excluded from the study.

RESULTS

Group A patients (54.28%) were prone to develop peripheral neuropathy comparing Group B (28.57%) and Group C (35%). There was significantly low plasma level of Cbl in Group A (mean 306.314 pg/ml) than in Group B (mean 627.543 pg/ml) and Group C (mean 419.920 pg/ml). There was insignificant low-level plasma folic acid in Group A (16.47 ng/ml) than in Group B (16.81 ng/ml) and Group C (22.50 ng/ml). There was significantly high level of Hcy in Group A (mean 17.35 µmol/L) and Group C (mean 16.99 µmol/L) than in Group B (mean 13.22 µmol/L). Metformin users even for 2 years showed evidence of neuropathy on nerve conduction velocity though their body mass index and postprandial blood sugar were maintained. There was significant difference in between groups regarding plasma Cbl, folic acid, and Hcy level as significance level <0.05 in all three groups (F [2, 87] = 28.1, P = 0.000), (F [2, 87] = 7.43, P = 0.001), (F [2, 87] = 9.76, P = 0.000). Post hoc study shows significant (P < 0.05) lowering of Cbl and Hcy level in Group A (mean = 306.314, standard deviation [SD] = 176.7) than in Group C (mean = 419.92, SD = 208.23) and Group B (mean = 627.543, SD = 168.33).

DISCUSSION

Even short-term treatment with metformin causes a decrease in serum Cbl folic acid and increase in Hcy, which leads to peripheral neuropathy in Type 2 diabetes patients. A multicenter study with heterogeneous population would have increased the power of the study. We suggest prophylactic Vitamin B₁₂ and folic acid supplementation or periodical assay in metformin user.

Multivitamin Use and Serum Vitamin B12 Concentrations in Older-Adult Metformin Users in REGARDS, 2003-2007

Metformin, an insulin-sensitizing drug, is a first line treatment for type 2 diabetes. Long-term use of metformin has been associated with subsequent reductions in vitamin B12 concentrations. The objective of our study was to determine whether metformin use is associated with lower serum vitamin B12 concentrations in older adults, and whether concurrent use of multivitamins modifies this association. We examined 2,510 participants aged 50 years and over, participating in the national population-based Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study. Multivariable linear and logistic regression models were used to assess associations between multivitamin use and serum vitamin B12 concentrations. We estimated adjusted odds ratios (aOR)s and confidence intervals (CI)s. Results were stratified by three metformin/diabetes sub-groups: 1) participants with diabetes who were metformin users; 2) participants with diabetes who were not metformin users; and 3) participants without diabetes. We found that diabetic metformin users had significantly lower geometric mean serum B12 concentrations (409 pmol/L) than the group with diabetes not taking metformin (485 pmol/L; P<0.01), and the group without diabetes (445 pmol/L; P = 0.02). The geometric mean serum B12 concentrations were greater for multivitamin users (509 pmol/L) compared to those who did not use multivitamins (376 pmol/L; p<0.01). Among the participants with diabetes who were on metformin therapy, multivitamin use was associated with geometric mean serum vitamin B12 concentrations that were 50% (or 161 pmol/L) higher, compared to those not using multivitamins. Among metformin users, multivitamin use was associated with lower prevalence of combined low and borderline vitamin B12 concentrations (aOR = 0.14; 95% CI = 0.04, 0.54) compared to those not using multivitamins. In conclusion, metformin use was associated with lower geometric mean serum vitamin B12 concentrations among diabetic older adults compared to their counterparts. Concurrent multivitamin use may potentially protect against low or borderline vitamin B12 concentrations in long-term metformin users. Additional research is needed to further examine this association as low or borderline vitamin B12 concentrations can be preventable, or treatable if detected at an early stage, in long-term metformin users.

Comparison of 2 Population Health Management Approaches to Increase Vitamin B12 Monitoring in Patients Taking Metformin

BACKGROUND

Population health management uses proactive, targeted interventions to improve health outcomes.

OBJECTIVES

To compare the effectiveness of and time required for 2 pharmacist-driven population health management interventions to improve vitamin B12 monitoring in patients taking metformin.

METHODS

Physicians were randomized to 1 of 2 population health management interventions. For all patients of physicians assigned to the patient portal intervention, a pharmacist communicated need for vitamin B12 monitoring directly to the patient using an electronic patient portal. For all patients of physicians assigned to the office visit intervention, a pharmacist communicated monitoring recommendations to the physician prior to a scheduled office visit through the electronic health record. The proportion of patients in each group who received vitamin B12 monitoring 30 days after the intervention was quantified.

RESULTS

A total of 489 patients of 26 physicians within 5 general internal medicine clinics who had taken metformin for at least 1 year and had not received vitamin B12 monitoring within the past year were identified. The intervention delivered as part of an office visit resulted in increased serum vitamin B12 monitoring compared with the intervention using electronic communication through a patient portal (odds ratio = 4.05; 95% CI = 1.22, 13.46; P = 0.03). The office visit intervention and the patient portal intervention took an average of 8.2 and 0.9 minutes per patient, respectively.

CONCLUSIONS

Population health management completed during the course of office visits was more effective at increasing vitamin B12 monitoring and required more time than an intervention delivered through an electronic patient portal.

Oral manifestations in vitamin B12 deficiency patients with or without history of gastrectomy

BACKGROUND

The purpose of this study was to compare clinical features of vitamin B12 deficiency patients with a history of gastrectomy to those without a history of gastrectomy.

METHODS

Twenty-two patients with vitamin B12 deficiency were included. Patients' chief complaints, oral manifestations, blood examination results, and past medical histories were reviewed.

RESULTS

Eleven patients had a history of gastrectomy and 11 did not. The chief complaint was glossodynia in all patients. No significant differences were observed between the two groups regarding age, sex, symptom duration, or plasma vitamin B12 level. Erythema and depapillation of the tongue were the most common findings, however less common among patients without a history of gastrectomy. Two patients with a history of gastrectomy and 5 patients without a history of gastrectomy had normal oral mucosa. Patients with a history of gastrectomy were more anemic. Oral symptoms of the majority of patients responded to antifungals and vitamin B12 replacement. The suggested etiologies for vitamin B12 deficiency in the patients without a history of gastrectomy were gastritis, medications, diet, autoimmunity, and early gastric cancer.

CONCLUSIONS

Vitamin B12 deficiency and its associated etiological factors should be considered in patients with glossodynia, even those whose oral mucosa appears normal and who lack a history of gastrectomy.

Association between metformin and vitamin B12 deficiency in patients with type 2 diabetes: A systematic review and meta-analysis

AIM

Metformin is the most widely used oral hypoglycaemic drug, but it may lower B₁₂ status, which could have important clinical implications. We undertook a systematic review and meta-analysis of the relationship between metformin use and vitamin B₁₂ deficiency in persons with type 2 diabetes.

METHODS

Electronic database searches were undertaken (1st January 1957-1st July 2013) using the Cochrane library, Scopus, CINAHL, Grey literature databases, Pub Med Central, NICE Clinical Guidelines UK, and ongoing clinical trials. Included studies were of any study design, with data from patients with type 2 diabetes of any age or gender, taking any dose or duration of metformin. Planned primary outcomes were serum vitamin B₁₂ levels, % prevalence or incidence of vitamin B₁₂ deficiency and risk of vitamin B₁₂ deficiency.

RESULTS

Twenty-six papers were included in the review. Ten out of 17 observational studies showed statistically significantly lower levels of vitamin B₁₂ in patients on metformin than not on metformin. Meta-analysis performed on four trials demonstrated a statistically significant overall mean B₁₂ reducing effect of metformin of 57pmol/L [WMD (fixed)=-0.57 (95% CI: -35 to -79pmol/L)] after 6weeks to 3months of use.

CONCLUSION

The evidence from this review demonstrates an association between metformin usage and lower levels of vitamin B₁₂ by 57pmol/L, which leads to frank deficiency or borderline status in some patients with type 2 diabetes. This suggests that it is prudent to monitor B₁₂ levels in these patients who are at increased risk of deficiency.

Depression among people with type 2 diabetes mellitus, US National Health and Nutrition Examination Survey (NHANES), 2005-2012

BACKGROUND

Depression in people with diabetes can result in increased risk for diabetes-related complications. The prevalence of depression has been estimated to be 17.6 % in people with type 2 diabetes mellitus (T2DM), based on studies published between 1980 and 2005. There is a lack of more recent estimates of depression prevalence among the US general T2DM population.

METHODS

The present study used the US National Health and Nutrition Examination Survey (NHANES) 2005-2012 data to provide an updated, population-based estimate for the prevalence of depression in people with T2DM. NHANES is a cross-sectional survey of a nationally representative sample of the civilian, non-institutionalized US population. Starting from 2005, the Patient Health Questionnaire (PHQ-9) was included to measure signs and symptoms of depression. We defined PHQ-9 total scores ≥ 10 as clinically relevant depression (CRD), and ≥ 15 as clinically significant depression (CSD). Self-reported current antidepressant use was also combined to estimate overall burden of depression. Predictors of CRD and CSD were investigated using survey logistic regression models.

RESULTS

A total of 2182 participants with T2DM were identified. The overall prevalence of CRD and CSD among people with T2DM is 10.6 % (95 % confidence interval (CI) 8.9-12.2 %), and 4.2 % (95 % CI 3.4-5.1 %), respectively. The combined burden of depressive symptoms and antidepressants may be as high as 25.4 % (95 % CI 23.0-27.9 %). Significant predictors of CRD include age (younger than 65), sex (women), income (lower than 130 % of poverty level), education (below college), smoking (current or former smoker), body mass index (≥30 kg/m(2)), sleep problems, hospitalization in the past year, and total cholesterol (≥200 mg/dl). Significant predictors of CSD also include physical activity (below guideline) and cardiovascular diseases.

CONCLUSIONS

The prevalence of CRD and CSD among people with T2DM in the US may be lower than in earlier studies, however, the burden of depression remains high. Further research with longitudinal follow-up for depression in people with T2DM is needed to understand real world effectiveness of depression management.

Association Between Serum B12 and Serum Homocysteine Levels in Diabetic Patients on Metformin

INTRODUCTION

Type-2 Diabetes Mellitus (T2DM) and metformin both can lower serum B12 (s.B12). Raised serum Homocysteine (s.Hcy) is considered as an early marker of B12 deficiency.

AIM

The study aimed to check whether homocysteine levels are more sensitive indicator of s. B12 deficiency or not among diabetics using metformin.

MATERIALS AND METHODS

Mean s.B12 and s.Hcy levels of 30 cases (diabetics on metformin <5years) were compared with 30 diabetic controls not on metformin and 31 nondiabetic controls and statistically analysed by ANOVA and post-hoc tests.

RESULTS

No significant differences in either s.B12 mean or s.Hcy mean were found between cases and diabetic controls. s.B12 mean did not differ significantly but s.Hcy mean was significantly higher among nondiabetics as compared to diabetic control. s. B12 level of Nondiabetic group was in borderline category while mean s. B12 levels of cases and diabetic control groups was in normal category but nearer to the lower cut off. Mean s.Hcy values in all the groups were high. Pearson correlation showed strong association between s.B12 and s.Hcy in all the groups. Additionally equation based on linear regression was derived to calculate either of the s.B12 or s.Hcy. On Receiver Operative Characteristic (ROC) curve, area under curve value was 0.842 for the value of s.Hcy.

CONCLUSION

In this study neither metformin nor T2DM could be identified as a cause for s.B12 lowering and raised s.Hcy in the scenario of low normal levels of s.B12 (<300pmol/L). If B12 deficiency recognized early using s. Hcy, consequences due to B12 deficiency can be prevented or delayed among nondiabetics as well as among diabetics and metformin users.

Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study

CONTEXT

Vitamin B12 deficiency may occur with metformin treatment, but few studies have assessed risk with long-term use.

OBJECTIVE

To assess the risk of B12 deficiency with metformin use in the Diabetes Prevention Program (DPP)/DPP Outcomes Study (DPPOS).

DESIGN

Secondary analysis from the DPP/DPPOS. Participants were assigned to the placebo group (PLA) (n = 1082) or the metformin group (MET) (n = 1073) for 3.2 years; subjects in the metformin group received open-label metformin for an additional 9 years.

SETTING

Twenty-seven study centers in the United States.

PATIENTS

DPP eligibility criteria were: elevated fasting glucose, impaired glucose tolerance, and overweight/obesity. The analytic population comprised participants with available stored samples. B12 levels were assessed at 5 years (n = 857, n = 858) and 13 years (n = 756, n = 764) in PLA and MET, respectively.

INTERVENTION

Metformin 850 mg twice daily vs placebo (DPP), and open-label metformin in the metformin group (DPPOS).

MAIN OUTCOME MEASURES

B12 deficiency, anemia, and peripheral neuropathy.

RESULTS

Low B12 (≤ 203 pg/mL) occurred more often in MET than PLA at 5 years (4.3 vs 2.3%; P = .02) but not at 13 years (7.4 vs 5.4%; P = .12). Combined low and borderline-low B12 (≤ 298 pg/mL) was more common in MET at 5 years (19.1 vs 9.5%; P < .01) and 13 years (20.3 vs 15.6%; P = .02). Years of metformin use were associated with increased risk of B12 deficiency (odds ratio, B12 deficiency/year metformin use, 1.13; 95% confidence interval, 1.06–1.20). Anemia prevalence was higher in MET, but did not differ by B12 status. Neuropathy prevalence was higher in MET with low B12 levels.

CONCLUSIONS

Long-term use of metformin in DPPOS was associated with biochemical B12 deficiency and anemia. Routine testing of vitamin B12 levels in metformin-treated patients should be considered.

Changes in Body Weight Among People With Type 2 Diabetes Mellitus in the United States, NHANES 2005-2012

Purpose

To understand weight loss strategies, weight changes, goals, and behaviors in people with type 2 diabetes mellitus (T2DM) and whether these differ by ethnicity.

Methods

T2DM was identified by self-reported diagnosis using the NHANES 2005-2012 data, which also included measured and self-reported current body weight and height, self-reported weight the prior year, and self-reported aspired weight. Nineteen weight loss strategies were evaluated for association with ≥5% weight loss or weight gain versus <5% weight change.

Results

Among people with T2DM, 88.0% were overweight/obese (body mass index [BMI] ≥25 kg/m2) in the prior year and 86.1% the current year. About 60% of the overweight/obese took weight loss actions, mostly using diet-related methods with average weight lost <5%. Two most “effective” methods reported (smoking, taking laxatives/vomiting) are also potentially most harmful. Similar BMI distributions but different goals and behaviors about weight and weight loss were observed across ethnicity. Only physical activity meeting the recommended level and changing eating habits were consistently associated with favorable and statistically significant weight change.

Conclusions

Weight management in T2DM is an ongoing challenge, regardless of ethnicity/race. Among overweight/obese T2DM subjects, recommended level of physical activity and changing eating habits were associated with statistically significant favorable weight change.

Associations between Vitamin B-12 Status and Oxidative Stress and Inflammation in Diabetic Vegetarians and Omnivores

Diabetes is considered an oxidative stress and a chronic inflammatory disease. The purpose of this study was to investigate the correlations between vitamin B-12 status and oxidative stress and inflammation in diabetic vegetarians and omnivores. We enrolled 154 patients with type 2 diabetes (54 vegetarians and 100 omnivores). Levels of fasting glucose, glycohemoglobin (HbA1c), lipid profiles, oxidative stress, antioxidant enzymes activity, and inflammatory makers were measured. Diabetic vegetarians with higher levels of vitamin B-12 (>250 pmol/L) had significantly lower levels of fasting glucose, HbA1c and higher antioxidant enzyme activity (catalase) than those with lower levels of vitamin B-12 (≤250 pmol/L). A significant association was found between vitamin B-12 status and fasting glucose (r = −0.17, p = 0.03), HbA1c (r = −0.33, p = 0.02), oxidative stress (oxidized low density lipoprotein-cholesterol, r = −0.19, p = 0.03), and antioxidant enzyme activity (catalase, r = 0.28, p = 0.01) in the diabetic vegetarians; vitamin B-12 status was significantly correlated with inflammatory markers (interleukin-6, r = −0.33, p < 0.01) in diabetic omnivores. As a result, we suggest that it is necessary to monitor the levels of vitamin B-12 in patients with diabetes, particularly those adhering to a vegetarian diet.

Branched-chain amino acid catabolism fuels adipocyte differentiation and lipogenesis

Adipose tissue plays important roles in regulating carbohydrate and lipid homeostasis, though less is known about the regulation of amino acid metabolism in adipocytes. Here we applied isotope tracing to pre–adipocytes and differentiated adipocytes to quantify the contributions of different substrates to tricarboxylic acid metabolism and lipogenesis. In contrast to proliferating cells that use glucose and glutamine for acetyl–coenzyme A (AcCoA) generation, differentiated adipocytes increased branched chain amino acid (BCAA) catabolic flux such that leucine and isoleucine from media and/or protein catabolism accounted for as much as 30% of lipogenic AcCoA pools. Medium cobalamin deficiency caused methylmalonic acid accumulation and odd–chain fatty acid synthesis. B12 supplementation reduced these metabolites and altered the balance of substrates entering mitochondria. Finally, inhibition of BCAA catabolism compromised adipogenesis. These results quantitatively highlight the contribution of BCAAs to adipocyte metabolism and suggest that BCAA catabolism plays a functional role in adipocyte differentiation.

A dietary intervention for chronic diabetic neuropathy pain: a randomized controlled pilot study

Background:

Diabetic neuropathy is a common and often debilitating condition for which available treatments are limited. Because a low-fat plant-based diet has been shown to improve glycemic control in individuals with type 2 diabetes, we hypothesized that such a diet would reduce painful symptoms of diabetic neuropathy.

Methods:

In this 20-week pilot study, individuals with type 2 diabetes and painful diabetic neuropathy were randomly assigned to two groups. The intervention group was asked to follow a low-fat, plant-based diet, with weekly classes for support in following the prescribed diet, and to take a vitamin B12 supplement. The control group was asked to take the same vitamin B12 supplement, but received no other intervention. At baseline, midpoint and 20 weeks, clinical, laboratory and questionnaire data were collected. Questionnaires included an analog ‘worst pain' scale, Michigan Neuropathy Screening Instrument, global impression scale, Short Form McGill Pain Questionnaire, Neuropathy Total Symptom Score, a weekly pain diary and Norfolk Quality of Life Questionnaire.

Results:

After 20 weeks, body weight change with the intervention was −6.4 kg (95% confidence interval (CI) −9.4 to −3.4, P<0.001) in an effect size analysis. Electrochemical skin conductance in the foot improved by an average of 12.4 microseimens (95% CI 1.2–23.6, P=0.03) with the intervention in an effect size analysis. The between-group difference in change in pain, as measured by the McGill pain questionnaire, was −8.2 points (95% CI −16.1 to −0.3, P=0.04). Michigan Neuropathy Screening Instrument questionnaire score change was −1.6 points (95% CI −3.0 to −0.2, P=0.03).

Conclusions:

Improvements were seen in some clinical and pain measures. This pilot study suggests the potential value of a plant-based diet intervention, including weekly support classes, for treating painful diabetic neuropathy.

The pharmacokinetics of metformin and concentrations of haemoglobin A1C and lactate in Indigenous and non-Indigenous Australians with type 2 diabetes mellitus

AIMS

To compare the pharmacokinetics of metformin between diabetic Indigenous (Aboriginal and Torres Strait Islander) and non-Indigenous patients.

METHODS

An observational, cross-sectional study was conducted on type 2 diabetic Indigenous and non-Indigenous patients treated with metformin. Blood samples were collected to determine metformin, lactate, creatinine and vitamin B12 concentrations and glycosylated haemoglobin levels. A population model was used to determine the pharmacokinetic parameters.

RESULTS

The Indigenous patients (median age 55 years) were younger than the non-Indigenous patients (65 years), with a difference of 10 years (95% confidence interval 6-14 years, P < 0.001). The median glycosylated haemoglobin was higher in the Indigenous patients (8.5%) than in the non-Indigenous patients (7.2%), with a difference of 1.4% (0.8-2.2%, P < 0.001). Indigenous patients had a higher creatinine clearance (4.3 l h(-1) ) than the non-Indigenous patients (4.0 l h(-1) ), with a median difference of 0.3 l h(-1) (0.07-1.17 l h(-1) ; P < 0.05). The ratio of the apparent clearance of metformin to the creatinine clearance in Indigenous patients (13.1, 10.2-15.2; median, interquartile range) was comparable to that in non-Indigenous patients (12.6, 9.9-14.9). Median lactate concentrations were also similar [1.55 (1.20-1.88) vs. 1.60 (1.35-2.10) mmol l(-1) ] for Indigenous and non-Indigenous patients, respectively. The median vitamin B12 was 306 pmol l(-1) (range 105-920 pmol l(-1) ) for the Indigenous patients.

CONCLUSIONS

There were no significant differences in the pharmacokinetics of metformin or plasma concentrations of lactate between Indigenous and non-Indigenous patients with type 2 diabetes mellitus. Further studies are required in Indigenous patients with creatinine clearance <30 ml min(-1) .

Cobalamin status and its relation with depression, cognition and neuropathy in patients with type 2 diabetes mellitus using metformin

AIMS

To investigate the associations of vitamin B12 (cobalamin and holotranscobalamin) status with depression, cognition and neuropathy in patients with type 2 diabetes using metformin.

METHODS

In an observational study, among 550 type 2 diabetes patients using metformin, cobalamin and holotranscobalamin (holoTCII) levels were measured at the annual diabetes checkup, and deficiencies were defined as <148 and <21 pmol/L, respectively. Depression and cognitive function were assessed with corresponding International Classification of Primary Care codes and questionnaires; neuropathy with medical record data and a questionnaire. Confounding variables were retrieved from medical records. Multivariable logistic and linear regressions were used with cobalamin status as independent variable; depression, cognition and neuropathy as dependent variables.

RESULTS

The mean duration of diabetes was 8.4 years (±5.8); mean duration of metformin use was 64.1 months (±43.2), with a mean metformin dose of 1,306 mg/day. A sufficient cobalamin level was independently associated with a decreased risk of depression (OR 0.42; 95 % CI 0.23-0.78) and better cognitive performance (β = 1.79; 95 % CI 0.07-3.52) adjusted for confounders. This indicates that cobalamin-deficient patients had a 2.4 times higher chance of depression and a 1.79 point lower cognitive performance score. HoloTCII was not associated with any outcome.

CONCLUSIONS

Cobalamin deficiency was associated with an increased risk of depression and worse cognitive performance, while holoTCII was not. Screening for cobalamin deficiency may be warranted in diabetes patients using metformin. Physicians should consider a cobalamin deficiency in diabetes patients using metformin with a depression or cognitive decline.

Associations between medication use and homocysteine levels in an older population, and potential mediation by vitamin B12 and folate: data from the B-PROOF Study

BACKGROUND

Elevated homocysteine levels are a risk indicator for cardiovascular disease, fractures and cognitive decline. Previous studies indicated associations between homocysteine levels and medication use, including antihypertensive, lipid-lowering and antidiabetic medication. However, results were often contradictory and inconclusive. Our objective was to study the associations established previously in more detail by sub-classifying medication groups, and investigate the potential mediating role of vitamin B12 and folate status.

MATERIALS AND METHODS

Baseline data from the B-PROOF (B-vitamins for the PRevention Of Osteoporotic Fractures) study were used. We included 2,912 participants aged ≥65 years, with homocysteine levels of 12-50 μmol/L and creatinine levels ≤150 μmol/L, for whom self-reported medication data were available. We used multivariable linear regression models and analysis of covariance to assess the association between medication use and plasma homocysteine levels, and the potential mediation by serum vitamin B12 and folate.

RESULTS

The mean age was 74 years (standard deviation, 6.5), 50 % were women, and median homocysteine levels were 14 µmol/L [interquartile range, 13-17 µmol/L]. Higher mean homocysteine levels were observed in users vs. non-users for diuretics (15.2 vs. 14.9, p = 0.043), high-ceiling sulphonamide diuretics (16.0 vs. 14.9, p < 0.001), medication acting via the renin-angiotensin system (15.2 vs. 14.9, p = 0.029) and metformin (15.6 vs. 15.1, p = 0.006). Non-selective β-blocker use was associated with lower mean homocysteine levels (14.4 vs. 15.0, p = 0.019). Only this association was mediated by an underlying association with vitamin B12 and folate levels.

CONCLUSION

The associations between homocysteine levels and medication use appear to be fairly modest. Our results suggest that medication use is unlikely to contribute to clinically relevant changes in plasma homocysteine levels.

The role of metformin on vitamin B12 deficiency: a meta-analysis review

Metformin is the only biguanide oral hypoglycemic drug, that is used to treat patients with type-2 diabetes mellitus. There are some reports of metformin being associated with decreased serum levels of vitamin B12 (VB12). The objective of this study is to systematically analyze the impact of metformin on the frequency of VB12 deficiency and serum levels of VB12. A search of various databases provided 18 retrospective cohort studies and 11 randomized controlled trials. Pooled estimates of odds ratio with 95% confidence interval using random effect model were conducted. Studies were examined for heterogeneity, publication bias and sensitivity analysis. Separate analysis of randomized control trials (RCTs) including both low-risk and high-risk bias was also conducted. 29 studies were selected with a total of 8,089 patients. 19 studies were rated intermediate or high quality. Primary outcome suggested increased incidence of VB12 deficiency in metformin group (OR = 2.45, 95% CI 1.74-3.44, P < 0.0001.) Heterogeneity was relatively high (I(2) = 53%), with minor publication bias. Secondary outcome suggested lower serum VB12 concentrations in metformin group (Mean difference = -65.8, 95% CI -78.1 to -53.6 pmol/L, P < 0.00001) with high heterogeneity (I(2) = 98%,) and low publication bias. RCTs analysis of low-and high-risk group revealed similar trends. We conclude that metformin treatment is significantly associated with an increase in incidence of VB12 deficiency and reduced serum VB12 levels.

Influence of duration and dose of metformin on cobalamin deficiency in type 2 diabetes patients using metformin

Metformin use is associated with cobalamin (vitamin B12) deficiency. However, the influence of both duration and dose of metformin is unclear. Studies using holotranscobalamin, a marker for cellular cobalamin deficiency, are scarce. We therefore investigated the prevalence of cobalamin deficiency in type 2 diabetes patients using both markers, and its relation with duration and dose of metformin use. This cross-sectional study among 550 type 2 diabetes patients using metformin (mean daily dose 1,306 mg; mean duration 64 months) was conducted in four primary care centers in Utrecht, the Netherlands. Cobalamin and holotranscobalamin concentrations were measured at the annual diabetes check. Detailed information on metformin use and confounding variables was collected from medical records. The prevalence of a cobalamin deficiency was 28.1 %, while a holotranscobalamin deficiency occurred in 3.9 % of the patients. Adjusting for multiple confounders, a 1 mg/day increase in daily metformin dose was associated (p < 0.001) with 0.042 (95 % CI -0.060, -0.023) decrease in cobalamin concentrations. Similarly, a 10 g increase of cumulative metformin dose was associated (p = 0.006) with -0.070 (-0.12, -0.021) lower cobalamin concentrations after adjustment for confounders. Duration of metformin use was not associated with cobalamin concentrations after multivariable adjustment. Similar results were observed for holotranscobalamin. Cobalamin deficiency occurs frequently among diabetes patients using metformin. A higher daily and cumulative doses of metformin were strongly associated with lower cobalamin and holotranscobalamin concentrations, while duration was not. It is thus important to account for metformin dose in recommendations for screening for cobalamin deficiency.

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.

Metformin use in patients with type 2 diabetes mellitus is associated with reduced risk of deep vein thrombosis: a non-randomized, pair-matched cohort study

Background

Metformin, an insulin-sensitizer, may correct several physiologic abnormalities owing to insulin resistance in patients with type 2 diabetes mellitus (DM). The effects of metformin on venous thrombosis in patient with type 2 DM have not been reported. Our study strived to explore the relationship of metformin therapy and the subsequent development of deep vein thrombosis (DVT) using a nationwide, population-based database.

Methods

From 1997 to 2003, we identified a study cohort consisting of patients with type 2 DM using metformin 7154 cases in the National Health Insurance Research Database. A control cohort without metformin, matched for age, sex, comorbidities, and medications was selected for comparison.

Results

Of the 14945 patients (7167 patients with metformin vs. 7778 control), 60 (0.40%) patients developed DVT during a mean follow-up period of 3.74 years, including 16 (0.21%) from the cohort with metformin and 44 (0.56%) from the control group. Subjects with metformin experienced a 0.427 fold (95% confidence interval 0.240-0.758; P = 0.004) changes of risk reduction in development of DVT, which was independent of age, sex and co-morbidities. Kaplan-Meier analysis also revealed metformin therapy is associated with lower occurrence of DVT (log-rank test, P = 0.001).

Conclusions

Metformin may have protective effect in patients with type 2 DM for DVT.

Vitamin B12 in obese adolescents with clinical features of insulin resistance

Emerging evidence indicates an association between obesity, metformin use and reduced vitamin B12 status, which can have serious hematologic, neurologic and psychiatric consequences. This study aimed to examine B12 status in obese adolescents with pre-diabetes and/or clinical features of insulin resistance. Serum B12 was measured using chemiluminescence immunoassay in 103 (43 male, 60 female) obese (mean body mass index (BMI) z-score ± SD (2.36 ± 0.29)), adolescents aged 10 to 17 years, median (range) insulin sensitivity index of 1.27 (0.27 to 3.38) and 13.6% had pre-diabetes. Low B12 (<148 pmol/L) was identified in eight (7.8%) and borderline status (148 to 221 pmol/L) in an additional 25 (24.3%) adolescents. Adolescents with borderline B12 concentrations had higher BMI z-scores compared to those with normal concentrations (2.50 ± 0.22 vs. 2.32 ± 0.30, p = 0.008) or those with low B12 concentration (2.50 ± 0.22 vs. 2.27 ± 0.226, p = 0.041). In conclusion, nearly a third of obese adolescents with clinical insulin resistance had a low or borderline serum B12 status. Therefore, further investigations are warranted to explore the cause and the impact of low B12 status in obese pediatric populations.

Higher prevalence of metformin-induced vitamin B12 deficiency in sulfonylurea combination compared with insulin combination in patients with type 2 diabetes: a cross-sectional study

Long-term and high-dose treatment with metformin is known to be associated with vitamin B₁₂ deficiency in patients with type 2 diabetes. We investigated whether the prevalence of B₁₂ deficiency was different in patients treated with different combination of hypoglycemic agents with metformin during the same time period. A total of 394 patients with type 2 diabetes treated with metformin and sulfonylurea (S+M group, n = 299) or metformin and insulin (I+M group, n = 95) were consecutively recruited. The vitamin B₁₂ and folate levels were quantified using the chemiluminescent enzyme immunoassay. Vitamin B₁₂ deficiency was defined as vitamin B₁₂≤300 pg/mL without folate deficiency (folate>4 ng/mL). The mean age of and duration of diabetes in the subjects were 59.4±10.5 years and 12.2±6.7 years, respectively. The mean vitamin B₁₂ level of the total population was 638.0±279.6 pg/mL. The mean serum B₁₂ levels were significantly lower in the S+M group compared with the I+M group (600.0±266.5 vs. 757.7±287.6 pg/mL, P<0.001). The prevalence of vitamin B₁₂ deficiency in the metformin-treated patients was significantly higher in the S+M group compared with the I+M group (17.4% vs. 4.2%, P = 0.001). After adjustment for various factors, such as age, sex, diabetic duration, duration or daily dose of metformin, diabetic complications, and presence of anemia, sulfonylurea use was a significant independent risk factor for B₁₂ deficiency (OR = 4.74, 95% CI 1.41–15.99, P = 0.012). In conclusion, our study demonstrated that patients with type 2 diabetes who were treated with metformin combined with sulfonylurea require clinical attention for vitamin B₁₂ deficiency and regular monitoring of their vitamin B₁₂ levels.

Childhood obesity and insulin resistance: how should it be managed?

OPINION STATEMENT

Concomitant with the rise in global pediatric obesity in the past decades, there has been a significant increase in the number of children and adolescents with clinical signs of insulin resistance. Given insulin resistance is the important link between obesity and the associated metabolic abnormalities and cardiovascular risk, clinicians should be aware of high risk groups and treatment options. As there is no universally accepted biochemical definition of insulin resistance in children and adolescents, identification and diagnosis of insulin resistance usually relies on clinical features such as acanthosis nigricans, polycystic ovary syndrome, hypertension, dyslipidemia, and nonalcoholic fatty liver disease. Treatment for reducing insulin resistance and other obesity-associated comorbidities should focus on changes in health behaviors to achieve effective weight management. Lifestyle interventions incorporating dietary change, increased physical activity, and decreased sedentary behaviors, with the involvement of family and adoption of a developmentally appropriate approach, should be used as the first line treatment. Current evidence suggests that the primary objective of dietary interventions should be to reduce total energy intake and a combination of aerobic and resistance training should be encouraged. Metformin can be used in conjunction with a lifestyle intervention program in obese adolescents with clinical insulin resistance to achieve weight loss and to improve insulin sensitivity. Ongoing evaluation and research are required to explore optimal protocol and long-term effectiveness of lifestyle interventions, as well as to determine whether the improvements in insulin sensitivity induced by lifestyle interventions and weight loss will lead to a clinical benefit including reduced cardiovascular morbidity and mortality.

Vitamin B12 deficiency is associated with adverse lipid profile in Europeans and Indians with type 2 diabetes

Background

Metformin, a standard therapy in type 2 diabetes, reduces vitamin B12 levels. Studies linking low vitamin B12 levels and cardiovascular disease are equivocal and suggest improving B12 levels may help in primary prevention. The role of vitamin B12 deficiency on cardiovascular risk factors, especially in type 2 diabetes has not been explored. The aim of this study is to investigate whether vitamin B12 deficiency in type 2 diabetes patients is associated with cardiovascular risk factors in two different ethnic groups in UK and India.

Methods

Type 2 diabetes patients from two secondary care diabetic centres (Europeans - UK and Indians - India) were studied. Serum vitamin B12, folate and biochemical parameters were measured.

Results

The prevalence rates of vitamin B12 deficiency (<191 ng/L) were 27% and 12% in Europeans and Indians, respectively and higher in metformin treated type 2 diabetes patients. In linear regression analysis, after adjusting for all likely confounding factors, vitamin B12 independently associated with triglycerides in both the populations and cholesterol/HDL ratio in Indians. Logistic regression showed type 2 diabetes patients with vitamin B12 deficiency were at significantly higher odds of having coexisting coronary artery disease (CAD) in Europeans with similar but non-significant trend in Indians, after adjusting for all likely confounding factors.

Conclusions

The prevalence of vitamin B12 deficiency is common in type 2 diabetes patients and is associated with adverse lipid parameters. Type 2 diabetes management guidelines should include the recommendation for regular testing for B12 levels, especially for those on metformin.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0129-4) contains supplementary material, which is available to authorized users.

Chronic kidney disease in US adults with type 2 diabetes: an updated national estimate of prevalence based on Kidney Disease: Improving Global Outcomes (KDIGO) staging

BACKGROUND

Kidney Disease Improving Global Outcomes (KDIGO) 2013 updated the classification and risk stratification of chronic kidney disease (CKD) to include both the level of renal function and urinary albumin excretion (UAE). The update subclassifies the previous category of moderate renal impairment. There is currently limited information on the prevalence of CKD based on this new classification in United States (US) adults with type 2 diabetes mellitus (T2DM). The objective of this study was to provide such estimates, for T2DM both overall and in those ≥ 65 years of age. We used the continuous National Health and Nutrition Examination Survey (NHANES) 1999-2012 to identify participants with T2DM. Estimated glomerular filtration rate (eGFR) and UAE were calculated using laboratory results and data collected from the surveys, and categorized based on the KDIGO classification. Projections for the US T2DM population were based on NHANES sampling weights.

RESULTS

A total of 2915 adults diagnosed with T2DM were identified from NHANES, with 1466 being age ≥ 65 years. Prevalence of CKD based on either eGFR or UAE was 43.5% in the T2DM population overall, and 61.0% in those age ≥ 65 years. The prevalence of mildly decreased renal function or worse (eGFR < 60/ml/min/1.73 m2) was 22.0% overall and 43.1% in those age ≥ 65 years. Prevalence of more severe renal impairment (eGFR < 45 ml/min/1.73 m2) was 9.0% overall and 18.6% in those age ≥ 65 years. The prevalence of elevated UAE (> 30 mg/g) was 32.2% overall and 39.1% in those age ≥ 65 years. The most common comorbidities were hypertension, retinopathy, coronary heart disease, myocardial infarction, and congestive heart failure.

CONCLUSIONS

This study confirms the high prevalence of CKD in T2DM, impacting 43.5% of this population. Additionally, this study is among the first to report US prevalence estimates of CKD based on the new KDIGO CKD staging system.

Association of vitamin B12 deficiency and metformin use in patients with type 2 diabetes

We evaluated the prevalence of vitamin B12 deficiency and associated factors in type 2 diabetes patients using metformin. A total of 799 type 2 diabetes patients using metformin was enrolled. Vitamin B12 and folate levels were quantified by chemiluminescent enzyme immunoassay. Vitamin B12 deficiency was defined as vitamin B12 ≤ 300 pg/mL without folate deficiency (folate > 4 ng/mL). The prevalence of vitamin B12 deficiency in metformin-treated type 2 diabetes patients was 9.5% (n = 76), and the mean vitamin B12 level was 662.5 ± 246.7 pg/mL. Vitamin B12 deficient patients had longer duration of metformin use (P < 0.001) and higher daily metformin dose (P < 0.001) than non-deficient patients. Compared with daily metformin dose of ≤ 1,000 mg, the adjusted odds ratio for 1,000-2,000 mg, and ≥ 2,000 mg were 2.52 (95% CI, 1.27-4.99, P = 0.008) and 3.80 (95% CI, 1.82-7.92, P < 0.001). Compared with metformin use of < 4 yr, the adjusted odds ratios for 4-10 yr, and ≥ 10 yr were 4.65 (95% CI, 2.36-9.16, P < 0.001) and 9.21 (95% CI, 3.38-25.11, P < 0.001), respectively. In conclusion, our study indicates that patients with type 2 diabetes treated with metformin should be screened for vitamin B12 deficiency, especially at higher dosages (> 1,000 mg) and longer durations (≥ 4 yr) of treatment.

A marriage of two "Methusalem" drugs for the treatment of psoriasis?: Arguments for a pilot trial with metformin as add-on for methotrexate

In this article we present arguments that the “antidiabetic” drug metformin could be useful as an add-on therapy to methotrexate for the treatment of psoriasis and, perhaps, for rheumatoid arthritis as well. Biochemical data suggest that both drugs may share a common cellular target, the AMP-activated protein kinase (AMPK). This enzyme is a master regulator of metabolism and controls a number of downstream targets, e.g., important for cellular growth or function in many tissues including T-lymphocytes. Clinical observations as well as experimental results argue for anti-inflammatory, antineoplastic and antiproliferative activities of metformin and a case-control study suggests that the drug reduces the risk for psoriasis.

Patients with psoriasis have higher risk of metabolic syndrome, type 2 diabetes and cardiovascular mortality. Metformin has proven efficacy in the treatment of prediabetes and leads to a pronounced and sustained weight loss in overweight individuals. We expect that addition of metformin to methotrexate can lead to positive effects with respect to the PASI score, reduction of the weekly methotrexate dose and of elevated cardiovascular risk factors in patients with metabolic syndrome and psoriasis. For reasons explained later we suggest that only male, overweight patients are to be included in a pilot trial. On the other side of the coin are concerns that the gastrointestinal side effects of metformin are intolerable for patients under low dose, intermittent methotrexate therapy. Metformin has another side effect, namely interference with vitamin B₁₂ and folate metabolism, leading to elevated homocysteine serum levels. As patients must receive folate supplementation and will be controlled with respect to their B₁₂ status increased hematological toxicity is unlikely to result.

Vitamin B12 status in metformin treated patients: systematic review

OBJECTIVE

Randomized controlled trials and observational studies have yielded inconsistent results on the effects of metformin on vitamin B12 reduction. We therefore performed a systematic review to analyze the effects of metformin on vitamin B12 concentration.

METHODS

PubMed, Medline, Embase, and the Cochrane central registry of controlled trials were searched to identify randomized controlled trials and observational studies exploring the association between metformin and vitamin B12 concentration in patients with type 2 diabetes mellitus or polycystic ovary syndrome. The main outcome measure was changes in serum vitamin B12 concentration after 6-208 weeks of treatment with metformin, as compared with placebo or other anti-hyperglycemic therapy.

RESULTS

Six randomized controlled trials met the inclusion criteria. Serum vitamin B12 concentrations were significantly lower in patients treated with metformin than in those who received placebo or rosiglitazone (mean difference [MD], -53.93 pmol/L; 95% confidence interval [CI], -81.44 to -26.42 pmol/L, P = 0.0001). Subgroup analysis identified four trials in which patients received a lower dose of metformin (<2000 mg/d) and two in which they received a higher dose (≥2000 mg/d), with MDs in vitamin B12 concentration after metformin treatment of -37.99 pmol/L (95% CI, -57.44 to -18.54 pmol/L, P = 0.0001) and -78.62 pmol/L (95% CI, -106.37 to -50.86 pmol/L, P<0.00001), respectively.

CONCLUSIONS

The reduction of vitamin B12 may be induced by metformin in a dose dependent manner.

Update on Safety Issues Related to Antihyperglycemic Therapy

The American Diabetes Association emphasizes the importance of individualized patient care in the management of diabetes. One of the important considerations in choosing an antihyperglycemic agent is its side-effect and safety profile. This article reviews the common and clinically significant side effects of each class of agents, including ways to prevent and overcome their occurrence.