Modifications in weight post cancer diabetes mellitus evaluation and risk based on populations study

Background: Cancer survivors are at an increased risk of developing type 2 diabetes mellitus (DM), and obesity is an important modifiable factor contributing to this risk. However, the influence of post-diagnosis weight changes on diabetes development among cancer survivors remains inadequately understood.Materials and Methods: This retrospective cohort study utilised data from the Indian National Health Insurance Service. Adults diagnosed with a new malignancy between 2021 and 2024 who completed national health examinations before and after their cancer diagnosis were included. Based on changes in body weight, participants were categorised into four groups: sustained normal weight, obese to normal weight, normal weight to obese, and sustained obese. Cox proportional hazards regression models were applied to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for incident DM after controlling for potential confounders.Results: A total of 264,250 cancer survivors were analysed. The sustained obese group demonstrated the greatest risk of developing DM (aHR 2.17; 95% CI: 2.08–2.26), followed by participants who transitioned from normal weight to obesity (aHR 1.66; 95% CI: 1.54–1.79) and those who reduced from obesity to normal weight (aHR 1.29; 95% CI: 1.21–1.39), compared with the sustained normal-weight group. Subgroup analyses across different cancer types consistently showed the highest diabetes risk among survivors who remained obese.Conclusion: Persistent obesity following a cancer diagnosis is strongly associated with an increased risk of developing diabetes mellitus. Although weight reduction from obesity lowers this risk, it does not completely eliminate it. Conversely, gaining weight after diagnosis significantly increases diabetes risk. These findings emphasize the importance of long-term weight management strategies as an integral component of survivorship care to reduce metabolic complications and improve overall health outcomes in cancer survivors.