Recent evidence supports the relationship between in-hospital hyperglycemia and inpatient complications. Besides, glycated hemoglobin (HbA1c) can predict the clinical course of patients with type 2 diabetes mellitus (DM2) during hospital stays. This study aimed to assess the relationship between HbA1c levels and inpatient outcomes. Type 2 diabetes mellitus patients with age greater than 18 years, hospital length of stay greater than 24 hours, and one HbA1c report during their in-hospital management were included. All the electronic care records of patients admitted at the Clinical Versalles, a high-volume institution, in Manizales-Colombia were revised. The following variables were considered: hospital length of stay, diagnoses at the arrival, complications, capillary glucose levels, and treatment at discharge. Variables were categorized by HbA1c levels: group 1 = ⩽ 7%, group 2 = 7.01% to 8.5%, group 3 = 8.51% to ⩽10% and group 4 = >10%. There were a total of 232 patients. Average age was 69.7 years, mean HbA1c was 7.19 ± 2.03, average body mass index (BMI) was 28.8 ± 5.6. About HbA1c, 146 (62.9%) had ⩽7.5%. The most frequent admission diagnosis was by cardiovascular diseases. Average hospitalization was 7.5 ± 5.7 days. There was no relationship between the levels of HbA1c with hospital stays, inpatient complications, or readmissions. Infections and respiratory diseases were more common conditions related to higher HbA1c levels, especially when these were 8.5%. In diabetic patients with nonsurgical diseases and high HbA1c levels, there was no association with clinical complications, length of stay, readmissions, or in-hospital mortality, but changes in treatment at discharge were observed.