The Impact of Type 2 Diabetes Mellitus on the Severity of Influenza Infection: A Single-centre Retrospective Observational Study from India

Background: Type 2 diabetes mellitus (T2DM) significantly impacts the severity of influenza infection, leading to higher risks of complications, prolonged hospitalisation, and increased mortality. Understanding this relationship is crucial for developing effective preventive and management strategies. Vaccination, glycaemic control, and timely antiviral treatment can help mitigate adverse outcomes and reduce the burden on healthcare systems. Methods: This retrospective study analysed 282 patients diagnosed with influenza from January 2024 to December 2024 in a tertiary care hospital. Data collected included demographic factors (age, gender) and clinical parameters (T2DM status, ICU stay, hospital stay duration, oxygen requirement, and mortality). Results: Among 292 patients, 168 (57.5%) had T2DM, while 124 (42.5%) were non-diabetic. The mean age was 58.9 years, with a male predominance. The average hospital stay was 8 ± 1.5 days. ICU admission was significantly higher in diabetic patients (58.9%) compared to non- diabetic patients (21%) ( P < .001). Oxygen requirement was also significantly higher in diabetic individuals (60.1%) than in non-diabetics (21.8%) ( P < .001). The controlled HbA1c level for a diabetic patient is 33% and the uncontrolled level is 67%. About 175 (60%) patients were vaccinated, and 117 (40%) were not. Mortality was notably higher in T2DM patients, demonstrating a strong association between diabetes and severe influenza-related complications. Conclusion: T2DM patients infected with influenza face significantly worse outcomes, including double the risk of mortality, triple the risk of hospitalisation, and quadruple the risk of ICU admission. These findings emphasise the critical need for routine influenza vaccination and optimised diabetes management to reduce severe complications in this high-risk population.