Addition of a Gastrointestinal Microbiome Modulator to Metformin Improves Metformin Tolerance and Fasting Glucose Levels

BACKGROUND

Adverse effects of metformin are primarily related to gastrointestinal (GI) intolerance that could limit titration to an efficacious dose or cause discontinuation of the medication. Because some metformin side effects may be attributable to shifts in the GI microbiome, we tested whether a GI microbiome modulator (GIMM) used in combination with metformin would ameliorate the GI symptoms.

METHODS

A 2-period crossover study design was used with 2 treatment sequences, either placebo in period 1 followed by GIMM in period 2 or vice versa. Study periods lasted for 2 weeks, with a 2-week washout period between. During the first week, type 2 diabetes patients (T2D) who experienced metformin GI intolerance took 500 mg metformin along with their assigned NM504 (GIMM) or placebo treatment with breakfast and with dinner. In the second week, the 10 subjects took 500 mg metformin (t.i.d.), with GIMM or placebo consumed with the first and third daily metformin doses. Subjects were permitted to discontinue metformin dosing if it became intolerable.

RESULTS

The combination of metformin and GIMM treatment produced a significantly better tolerance score to metformin than the placebo combination (6.78 ± 0.65 [mean ± SEM] versus 4.45 ± 0.69, P = .0006). Mean fasting glucose levels were significantly (P < .02) lower with the metformin-GIMM combination (121.3 ± 7.8 mg/dl) than with metformin-placebo (151.9 ± 7.8 mg/dl).

CONCLUSION

Combining a GI microbiome modulator with metformin might allow the greater use of metformin in T2D patients and improve treatment of the disease.

Contribution of Clostridium difficile infection to the development of lower gastrointestinal adverse events during autologous stem cell transplantation

BACKGROUND

Lower gastrointestinal (GI) adverse events (LGAE) are common afflictions of patients undergoing stem cell transplantation (SCT). Unfortunately, the pathophysiology remains poorly characterized. Emerging data suggest a prominent role of intestinal microbiota; however, contributions of pathogenic gut microbiota such as Clostridium difficile are not well defined. We performed a genome-wide association study (GWAS) to investigate clinical and genetic factors associated with development of LGAE.

METHODS

A total of 972 patients undergoing autologous SCT were graded for LGAE based on Common Terminology Criteria for Adverse Events (v 4.0). Germline DNA material was obtained from leukapharesis products and genotyped using Illumina(®) Whole Genome Genotyping Infinium chemistry and HumanOmni1-Quad Bead chips containing over 1.1 million single nucleotide polymorphisms (SNPs) (Illumina, San Diego, California, USA). Statistical models incorporating clinical factors, genetic factors, and a combination of clinical plus genetic factors were utilized to compare patients who developed severe LGAE (grade 2 or above) and others.

RESULTS

Among 972 patients, 459 (47.2%) developed severe LGAE. Baseline hemoglobin and hematocrit, estimated glomerular filtration rate, β2-microglobulin, protocol type, and C. difficile infection (CDI) were associated with severe LGAE on univariate analysis, Genomic comparisons between groups did not reveal any SNPs associated with severe LGAE and neither did incorporation of genetic factors into the clinical model. In addition, 11 candidate SNPs associated with upper GI mucositis were evaluated, alongside clinical factors in a multivariate model. Only CDI was found to be associated with severe LGAE in all models.

CONCLUSION

CDI is a prominent factor in the development of LGAE in patients undergoing autologous SCT.