Megha Garg, 41, a homemaker from Delhi, had no idea she was living with type 2 diabetes when she contracted H1N1 influenza this month. What began as an ordinary fever on August 12 quickly became a fight for breath.The fever kept rising, followed by a cough, cold and intense body pain. By the fourth day, Megha’s oxygen saturation had fallen to 80 per cent. She developed persistent chills despite taking paracetamol and antibiotics prescribed by a local pharmacist. Then blood began appearing when she coughed — haemoptysis, a potentially serious sign that prompted further evaluation of her lungs.She was admitted to Apollo Hospital on August 15, where she was diagnosed with H1N1 influenza. With her oxygen level at 80 per cent, she required oxygen therapy and non-invasive ventilation and was kept in isolation. Her condition was severe enough that doctors closely monitored her for further deterioration and the possible need for invasive ventilation.It was during this evaluation that doctors found another problem — one Megha had not known existed.Her HbA1c, a blood test that reflects average blood glucose levels over roughly the previous two to three months, was above the diabetic range.“She had undetected diabetes. She came to us with influenza, but during the evaluation, we found that her HbA1c was very high,” said Dr Nikhil Modi, Senior Consultant, Respiratory Medicine, Indraprastha Apollo Hospitals, New Delhi. The finding mattered. Diabetes can impair several aspects of the body’s immune response and is associated with a greater risk of complications from influenza and other infections. When a person is simultaneously battling a severe viral infection and uncontrolled blood sugar, doctors may have to manage two problems at once.“Patients with comorbidities such as diabetes, hypertension and cancer can take more time and effort to stabilise and have a higher risk of deterioration,” Dr Modi said.Story continues below this adThe science is simple“White blood cells may not respond as effectively to pathogens, while chronic metabolic stress can trigger abnormal inflammation. The result is a paradox: the immune system may be less efficient at clearing the virus, yet inflammation can still become excessive,” said Dr Modi.The problem isn’t simply “weak immunity.” It is poorly coordinated immunity. If early antiviral defences are delayed or weakened, H1N1 can potentially persist for longer. Experimental evidence suggests that elevated glucose can increase influenza infection and replication in respiratory epithelial cells, although the exact contribution of hyperglycaemia in humans remains an area of ongoing research. That creates a vicious cycle.Megha was treated with the antiviral oseltamivir, alongside respiratory support and treatment to bring her blood glucose under control. She remained in hospital for nearly a week and was discharged on August 22. Her diabetes, however, will now require long-term attention.She was prescribed insulin and diabetes medication in low doses after discharge. “In hospitalised patients with newly detected or markedly elevated blood sugar, doctors may use insulin because it allows glucose levels to be adjusted relatively quickly and under close monitoring. Longer-term treatment is then individualised once the acute illness settles,” said Dr Modi.Story continues below this adFor Megha’s family, recovery has meant a new routine. Her husband Tarun, who runs a local general store, has taken leave to care for her while their son manages the shop. “She is recovering at home now. She sleeps most of the time. I have taken leave from the shop to take care of her, and our son is managing the shop,” he said.Should we all be checking our blood sugar?Megha’s experience raises a question that extends beyond influenza: How many people are walking around with diabetes without knowing it?Type 2 diabetes can develop gradually and may cause few or no obvious symptoms in its early stages. That is why testing is particularly important for people with risk factors such as excess weight, a family history of diabetes, high blood pressure, abnormal cholesterol, a sedentary lifestyle, or a previous history of high blood sugar.A simple blood glucose test can provide a snapshot of current sugar levels, while an HbA1c test can help identify persistently elevated blood glucose over the preceding few months.Story continues below this adThat does not mean every healthy person needs to repeatedly test their sugar at home. Who should be screened, and how often, should depend on age, risk factors and a clinician’s assessment. But people who have never been tested — particularly those with diabetes risk factors — should discuss screening with their doctor rather than waiting for an infection or another illness to expose the problem.When can flu become dangerousMost people with influenza recover without needing hospitalisation. The danger is recognising the smaller group in whom the illness is progressing to pneumonia, respiratory failure or other complications.Warning signs that warrant urgent medical assessment include:Difficulty breathing or breathlessnessPersistently low oxygen saturation, particularly if measured accurately and accompanied by symptomsChest pain or pressureBluish or grey lips or faceConfusion, unusual drowsiness or difficulty wakingSevere weakness or dehydrationCoughing up bloodSymptoms that initially improve but then return or worsen, particularly fever and coughPeople with underlying conditions — including diabetes, chronic lung or heart disease, cancer or conditions that weaken immunity — may need earlier medical evaluation when they develop influenza-like illness.Sometimes the infection is not the only illness a patient is fighting. For patients and families, the practical message is simple: know your risk factors, get appropriate diabetes screening rather than waiting for symptoms, and do not ignore signs of respiratory deterioration during flu.