The scale of the problem is staggering. According to the International Diabetes Federation, roughly 589 million adults aged 20 to 79 were living with diabetes in 2024, a figure projected to reach 853 million by 2050, with the burden falling disproportionately on low- and middle-income countries. India alone accounts for an estimated 101 million adults with diabetes and another 136 million with prediabetes, according to the ICMR-INDIAB study. Meanwhile, GLOBOCAN 2022 tallied about 20 million new cancer cases and 9.7 million cancer deaths worldwide in a single year. A nationwide analysis cited in the review, involving nearly five million individuals, found increased cancer incidence in 21 of 24 common cancer types among people with diabetes, with relative risk increases ranging from 11 percent for non-Hodgkin lymphoma to more than 200 percent for liver cancer. The authors also note that diabetes and elevated body mass index together accounted for approximately 5.7 percent of all new cancers globally in 2012, some 804,100 cases.

The epidemiological picture is strikingly site-specific. Cancers of the pancreas, liver, colorectum, breast, endometrium, gallbladder, thyroid, and bladder show consistently higher incidence among people with type 2 diabetes. A North African cohort study found that 38.1 percent of pancreatic cancer patients had diabetes, and 42.7 percent of those had new-onset disease, hinting at a complex feedback loop in which early occult malignancy may itself trigger metabolic derangement. Data from the Southern Community Cohort Study showed diabetes conferred a hazard ratio of 5.4 for hepatocellular carcinoma in European Americans versus 1.8 in African Americans, suggesting ethnic differences in susceptibility. Colorectal cancer survivors carry a 20 percent higher risk of developing type 2 diabetes, particularly within the first decade after diagnosis, while a Lithuanian cohort reported a standardized incidence ratio of 1.69 for endometrial cancer among women with diabetes. Among women with breast cancer, diabetes was associated with sharply increased all-cause mortality, with a hazard ratio of 2.49 in those with obesity. Intriguingly, the one consistent exception is prostate cancer, where diabetes appears protective, possibly through lower testosterone and prostate-specific antigen levels and reduced detection rates.

Beneath these statistics lies a dense web of molecular mechanisms. Chronic hyperglycemia fosters the formation of advanced glycation end-products and reactive oxygen species, which directly damage DNA, producing mutations, strand breaks, and chromosomal instability, the raw material of early tumorigenesis. Glycation end-products also engage their receptor RAGE, igniting intracellular signaling that enhances inflammation and supports cancer cell survival. Insulin resistance, the hallmark of type 2 diabetes, drives compensatory hyperinsulinemia that chronically stimulates insulin and insulin-like growth factor 1 signaling, activating the PI3K/AKT and MAPK cascades that promote cell proliferation, block apoptosis, and spur angiogenesis. Altered circulating levels of IGF-1 and its binding proteins have been reported in oral, breast, colorectal, and liver malignancies, and in experimental models of hepatocellular carcinoma, hyperglycemia suppresses the tumor-suppressive gene ZNF334 through DNA hypermethylation.

Chronic low-grade inflammation supplies a third mechanistic pillar. Sustained metabolic stress in diabetes keeps pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor alpha elevated, activating the oncogenic transcription factors NF-κB and STAT3, which drive proliferation, angiogenesis, immune evasion, and metastasis in colorectal, breast, liver, and pancreatic cancers. The review highlights experimental evidence that histone deacetylase 3 is upregulated in type 2 diabetes, amplifying TNFα, IL-6, and NF-κB signaling, while anti-inflammatory regulators such as SIRT1 and DBC1 decline, locking immune and metabolic cells into a pro-inflammatory state. Preclinical work further suggests that poly(ADP-ribose) polymerase 1, or PARP1, may amplify inflammation-associated oncogenic signaling, although the authors caution that its relevance to the diabetes-cancer axis in humans remains unproven.

Metabolic reprogramming completes the loop. Both diseases share deranged energy handling: lipid accumulation, mitochondrial dysfunction, and impaired oxidative phosphorylation in diabetes create a metabolic milieu that favors the Warburg effect, the aerobic glycolysis exploited by tumors for rapid ATP generation and biomass production. Key glycolytic regulators such as pyruvate kinase M2 and hypoxia-inducible factor 1-alpha are central players, and elevated lactate, common to both conditions, worsens insulin resistance while also acting as an epigenetic modifier by inhibiting histone deacetylases, relaxing chromatin, and activating oncogenic genes. Reduced NAD+ availability in diabetes impairs sirtuin activity, weakening cellular defenses against oxidative stress. In other words, the diabetic metabolic state does not merely coexist with cancer metabolism; it can amplify it.

The review’s most provocative claim is that epigenetics serves as the molecular memory that stabilizes these transient metabolic insults into durable cancer risk. DNA methylation, catalyzed by the methyltransferases DNMT1, DNMT3A, and DNMT3B using S-adenosyl methionine as the methyl donor, generally silences genes when deposited at promoters. In diabetes, methylation patterns shift at genes governing insulin secretion and glucose metabolism; in cancer, the same machinery silences tumor suppressors and activates oncogenes. Histone acetylation and methylation are equally sensitive to metabolism, since the enzymes that write these marks depend on metabolites such as acetyl-CoA and alpha-ketoglutarate, whose availability is distorted by hyperglycemia and lipotoxicity. Non-coding RNAs, including microRNAs and long non-coding RNAs, add a post-transcriptional layer, while chromatin remodeling complexes such as SWI/SNF reposition nucleosomes in response to metabolic and inflammatory cues. Because these marks are heritable yet reversible, they explain a puzzling clinical observation: cancer risk in people with diabetes can persist even after glycemic control improves.

Several emerging frontiers extend this framework, though the authors are careful to flag them as hypothesis-generating. Epigenetic clocks such as GrimAge and DunedinPACE show accelerated biological aging in people with metabolic syndrome and diabetes, independent of lifestyle factors, and poor glycemic control is associated with widespread methylation changes that may hasten aging and oncogenic transformation. Metformin has been linked in some studies to slower epigenetic aging, hinting at a modifiable target. Diabetes-associated gut dysbiosis, marked by loss of short-chain fatty acid-producing bacteria and increased intestinal permeability, allows lipopolysaccharides to enter circulation and directly alter host DNA methylation, histone acetylation, and microRNA expression, while depleting protective metabolites such as butyrate, folate, and vitamin B12. Sex-specific epigenetic signatures, including differential methylation at loci such as ABCG1, HOOK2, and PDGFA and sex-biased microRNA profiles involving miR-93, miR-199a, miR-21, and miR-155, may partly explain why diabetes progression and cancer susceptibility diverge between men and women, though most of this evidence remains observational.

The therapeutic implications cut in both directions. Cancer treatment itself is diabetogenic: glucocorticoids induce insulin resistance and hepatic gluconeogenesis, mTOR and PI3K/AKT inhibitors impair insulin signaling, immune checkpoint inhibitors can trigger autoimmune diabetes resembling type 1 disease, and androgen deprivation therapy significantly raises diabetes risk in prostate cancer patients, particularly with long-term use. Conversely, antidiabetic drugs carry oncologic signals: metformin is most consistently associated with reduced cancer risk, potentially through AMPK activation and mTOR inhibition, while pioglitazone showed a statistically significant association with bladder cancer in one large UK cohort, a drug-specific effect not seen with rosiglitazone and questioned by later meta-analyses. Evidence for insulin, sulfonylureas, DPP4 inhibitors, GLP-1 receptor agonists, and SGLT2 inhibitors remains inconsistent or immature. Meanwhile, epigenetic therapies, including HDAC inhibitors such as vorinostat and romidepsin, DNMT inhibitors such as decitabine, and RNA-based approaches targeting microRNAs, offer a precision route to reverse diabetes-associated chromatin states that favor tumorigenesis.

The authors’ bottom line is a call for integrated, anticipatory care. Diabetes clinics may serve as early warning stations for occult malignancy, especially in patients with unexplained weight loss, anemia, jaundice, or persistent inflammatory markers, while oncology patients exposed to glucocorticoids, targeted agents, or pancreatic irradiation deserve periodic glycemic surveillance. Lifestyle interventions that modulate inflammation, insulin sensitivity, and epigenetic programming, including physical activity and dietary change, may simultaneously lower risk for both diseases. Much of the epigenetic evidence remains observational, derived from animal models, small cohorts, or heterogeneous clock algorithms, and the review is candid about these gaps. But the convergence of epidemiology, molecular biology, and chromatin science now makes a compelling case that diabetes and cancer are not merely co-travelers of aging and adiposity; they are active collaborators, and the epigenome is where their pact is signed.

Subject of Research: The bidirectional relationship between diabetes and cancer and the epigenetic mechanisms linking them

Article Title: The Bidirectional Relationship Between Diabetes and Cancer: Mechanistic Insights, Epigenetic Intermediaries, and Therapeutic Approaches

Article References: The Bidirectional Relationship Between Diabetes and Cancer: Mechanistic Insights, Epigenetic Intermediaries, and Therapeutic Approaches. (n.d.). https://doi.org/10.1007/s13300-026-01926-9

Image Credits: AI Generated

DOI: 10.1007/s13300-026-01926-9

Keywords: diabetes, cancer, epigenetics, insulin resistance, hyperglycemia, chronic inflammation, metabolic reprogramming, DNA methylation, epigenetic aging, microbiome, metformin, precision medicine