Chronic Obstructive Pulmonary Disease (COPD): Given the patient's significant smoking history (40 pack-years), symptoms of worsening dyspnea, productive cough, wheezing, and diminished breath sounds, COPD is the most likely diagnosis. The patient's history of smoking, even though she quit 15 years ago, increases her risk for COPD.

Asthma: Although less likely than COPD due to the patient's age and smoking history, asthma cannot be ruled out, especially with symptoms of wheezing and cough. Asthma can develop at any age and may be exacerbated by environmental factors or comorbid conditions.
Congestive Heart Failure (CHF): The patient's symptoms of worsening dyspnea, fatigue, and being winded from minimal exertion could also suggest CHF, particularly in the context of her type 2 diabetes, which is a risk factor for heart disease.
Pneumonia: Although the patient does not have a fever mentioned, pneumonia should be considered, especially with symptoms of productive cough and diminished breath sounds. Elderly patients may not always present with typical symptoms of infection.

Pulmonary Embolism (PE): This is a critical diagnosis not to miss, as it can be fatal if not treated promptly. While the patient's symptoms do not classically suggest PE (e.g., sudden onset of dyspnea, chest pain), her age, immobility (implied by being winded from walking across her home), and history of osteoporosis (which may increase the risk of immobilization and thus venous thromboembolism) make it essential to consider.
Lung Cancer: Given her significant smoking history, lung cancer is a possibility, especially if she has had no recent evaluation for lung cancer screening. Symptoms could include worsening cough, dyspnea, and diminished breath sounds, although these are non-specific.

Cystic Fibrosis: Although extremely rare in a 72-year-old, cystic fibrosis can present later in life, especially in individuals with mild mutations. However, this diagnosis would be highly unusual and would require further testing for confirmation.
Alpha-1 Antitrypsin Deficiency: This genetic disorder can cause COPD-like symptoms and is more common in smokers. It's a rare condition but should be considered in patients with a significant smoking history and symptoms suggestive of COPD, especially if they are not responding to typical COPD management.
Eosinophilic Pneumonia: A rare condition characterized by an accumulation of eosinophils in the lungs, which can cause respiratory symptoms. It might be considered if the patient does not respond to typical treatments for more common conditions and if eosinophilia is found on laboratory tests.