Anemia of Chronic Disease: Given the patient's history of diabetes mellitus (DM) and hypertension (HTN), along with the laboratory values indicating anemia (low Hgb and Hct), anemia of chronic disease is a plausible diagnosis. Chronic diseases like DM can lead to anemia due to various mechanisms, including decreased erythropoietin production, inflammation, and oxidative stress.

Iron Deficiency Anemia: Although the patient's history does not specifically mention gastrointestinal symptoms or dietary deficiencies, iron deficiency anemia is a common condition that could explain the low hemoglobin and hematocrit levels. Further testing, such as serum iron and ferritin levels, would be necessary to confirm this diagnosis.
Chronic Kidney Disease (CKD) related Anemia: Given the patient's history of HTN and DM, both of which are risk factors for CKD, anemia related to CKD is a possible diagnosis. CKD can lead to decreased erythropoietin production, resulting in anemia.

Myelodysplastic Syndrome (MDS): Although less common, MDS is a condition that can present with anemia and should not be missed due to its potential for progression to acute leukemia. The patient's age and anemia without an obvious cause make MDS a "do not miss" diagnosis.
Gastrointestinal Bleeding: A source of chronic blood loss, such as gastrointestinal bleeding, could explain the anemia. This condition is critical to identify due to the potential for significant morbidity and mortality if left untreated.

Sideroblastic Anemia: A rare form of anemia characterized by the presence of ringed sideroblasts in the bone marrow. It can be congenital or acquired and is associated with various conditions, including myelodysplastic syndromes.
Pernicious Anemia: An autoimmune condition leading to vitamin B12 deficiency due to impaired absorption. Although rare, it's an important diagnosis to consider in patients with anemia, especially if they have neurological symptoms or a family history of autoimmune diseases.