A Double-Blind, Placebo-Controlled Trial of Anti-Aging, Pro-Autophagy Effects of Metformin in Adults With Prediabetes

Anti-aging medicine is a burgeoning field. Accumulating evidence implicates the cellular process of autophagy as a primary mechanism of normal aging and the diseases associated with it. Autophagy is a process of "cellular recycling" and is known to affect a spectrum of health and disease states associated with aging, including inflammatory disorders, metabolic syndrome, type 2 diabetes, cardiovascular disease, cancer, and neurodegeneration. The dynamics of autophagy are controlled by autophagy-related genes and by one of the central regulators of metabolism, AMPK (the target of metformin). Autophagy also affects stem cells and cellular senescence. When the process of autophagy fails, the result is a state of chronic inflammation and degeneration in many organ systems.

Numerous studies have documented the metabolic benefits conferred by the glucose lowering agent metformin. In animal models, metformin has been shown to increase both lifespan and health-span, and a clinical trial (NCT02432287) is currently ongoing to determine whether this effect translates to humans, with additional investigation into how the medication alters the adult human transcriptome. In vitro studies demonstrate metformin's ability to mitigate aging- and disease-related inflammation, oxidative damage, and diminished autophagy. Additionally, there are numerous cohort, case-control and meta-analysis studies confirming metformin's reduction in cancer-related death via hypothesized activity in the relevant mTOR, human epidermal growth factor receptor 2 (HER2), micro-Ribosomal Nucleic Acid (miRNA) and transcription growth factor alpha (TGF-alpha) pathways and processes. As such, the National Institutes of Health (NIH) has issued an Funding Opportunity Announcement (FOA) parent announcement PA-17-073 (https://grants.nih.gov/grants/guide/pa-files/PA-17-073.html) to solicit additional clinical studies that will evaluate metformin's effects on aging and age-related conditions.

The long term goal of this study is to develop a Phase III study in response to this FOA using leucocyte LC3, transcription factor EB (TFEB) scores, total DNA methylation and galectin-3 to gauge the magnitude of metformin's effects on autophagy and cellular senescence as proxies for aging in adults with prediabetes. This study will provide preliminary data for such a proposal, and it will fill a knowledge gap regarding the use of validated biomarkers in this arena. It will also contribute significantly to the anti-aging literature. The primary objective of this proposal is to validate the autophagy-related experimental design by using leucocyte LC3 as a marker of autophagy and cellular senescence in humans.

Aim: Demonstrate that metformin therapy will increase cellular autophagy as an inverse correlate of aging as measured by increases in LC3 scores.

Hypothesis 1: In addition to beneficial effects on glycemia, body weight, and body composition, metformin therapy exerts beneficial effects on surrogate measures of autophagy and aging.

Primary outcome: Increased levels of LC3.

FUTURE DIRECTIONS Confirmation of improvement in markers of autophagy resulting from treatment with metformin will justify the submission of grant proposals for more definitive clinical trials examining the effect of metformin on actual clinical outcomes (as opposed to surrogate measures) in pursuit of a potential Food and Drug Administration (FDA) indication for metformin as an anti-aging therapy.

Inclusion criteria

• Adults with prediabetes (defined as an A1c of 5.7-6.4%)
• BMI between 27 and 40 kg/m2 (inclusive).

Exclusion criteria

• Prior treatment with metformin or other diabetes medications,
• Pregnancy,
• Significant renal dysfunction (Serum Creatinine > 1.3 mg/dl for women, > 1.4 mg/dl for men),
• Severe hepatic dysfunction (aspartate amnotransferease [AST] or alanine aminotransferase [ALT] > 3 times the upper limit of normal),
• Ongoing alcohol or substance abuse,
• Inflammatory bowel disease,
• Ongoing glucocorticoid therapy,
• Or inability to render informed consent.