Background: Diabetes management in patients with hematologic malignancies is challenging because of advanced age, multimorbidity, and cancer-related therapies. However, real-world evidence regarding glycemic control in this population remains limited. We aimed to evaluate glycemic control, glucose-lowering treatment patterns, and factors associated with tight glycemic control in patients with type 2 diabetes and hematologic malignancies. Methods: This retrospective cross-sectional study included 86 adults treated at a tertiary university hematology department. Demographic, clinical, laboratory, and treatment data were extracted from medical records. Low measured glycated hemoglobin (HbA1c) was defined as HbA1c <6.5%. Associated factors were examined using exploratory multivariable logistic regression. Results: The mean age was 75.0 ± 11.6 years; 48 patients (55.8%) were men. Among the 80 patients with available HbA1c measurements, the median HbA1c was 6.6% (interquartile range 6.0–7.2), and 37 (46.3%) had HbA1c <6.5%. Exploratory regression analyses suggested higher odds of HbA1c <6.5% with higher estimated glomerular filtration rate (adjusted odds ratio [OR], 1.03; 95% confidence interval [CI], 1.002–1.055; p = 0.035) and lower odds with diabetic vascular complications (adjusted OR, 0.30; 95% CI, 0.09–0.99; p = 0.048). At the alternative HbA1c threshold of <7.0%, corticosteroid exposure was associated with lower odds (adjusted OR, 0.35; 95% CI, 0.13–0.98; p = 0.046). Fifteen patients (18.8%) had HbA1c <6.5% while receiving insulin and/or a sulfonylurea. Conclusions: Low HbA1c values were common in this cohort, including among patients receiving insulin and/or sulfonylureas. These findings describe low measured HbA1c and associated treatment patterns but do not establish unnecessarily intensive treatment, clinical inappropriateness, hypoglycemia, or treatment-related harm. Prospective studies incorporating individualized treatment targets and documented hypoglycemia are needed to clarify their clinical significance.