Hello Thanks for your query. Dry cough in a diabetic patient may be because of many reasons like asthma, eosinophilic pneumonia, associated vasculitis, tropical pulmonary eosinophilia, drug reactions, GERD etc. Therefore you need to first undergo a detailed evaluation of the cause of the cough through following panel of investigations like - 1. Chest X-ray PA view 2. Sputum eosinophil count 3. Absolute eosinophil count 4. Spirometry with bronchodialator reversibility 5. Total serum IgE level Consult a good pulmonologist and get yourself examined. With all these probably you will get an answer to your cough. Thank you Regards Dr Arnab Maji