Thanks for your question on Health Care Magic. I can understand your concern. Most common cause for pleural effusion is heart diseases. Congestive heart failure causes fluid over load and hence accumulation of fluid in the pleural cavity. Her chest pain is not improving with anti tb drugs, so we need to rule out other causes for pleural effusion. Since your mother is having diabetes and hypertension, we should first rule out heart failure as a cause for pleural effusion. So better to get done ecg and 2d echo first. If these are suggestive of heart disease then she will need diuretics and cardiac inotropic drugs. Another possibility is Pulmonary embolism and infarction. So get done CT Pulmonary Angiography. So consult doctor and discuss all these. Hope I have solved your query. Wishing good health to your mother. Thanks.