Introduction

Type 2 diabetes mellitus (T2DM) is a major global health problem and one of the leading causes of chronic morbidity worldwide. The International Diabetes Federation estimated that 589 million adults were living with diabetes in 2024, with projections suggesting a continued increase over the coming decades [1]. In Mexico, diabetes represents a particularly important public health challenge, with national survey data reporting a high prevalence of both diagnosed and undiagnosed diabetes among adults [2].

Maintaining adequate glycemic control is central to reducing the risk of diabetes-related complications. Long-term hyperglycemia has been strongly associated with microvascular and macrovascular outcomes in patients with T2DM [3]. Follow-up data from landmark diabetes studies have also shown that early intensive glucose control may provide durable benefits on diabetes-related outcomes over time [4]. Glycated hemoglobin (HbA1c) remains one of the most widely used markers for long-term glycemic assessment, and an HbA1c goal below 7% is commonly recommended for many nonpregnant adults, although individualized targets are emphasized according to age, comorbidities, hypoglycemia risk, and treatment burden [5].

Pharmacologic management of T2DM typically begins with lifestyle modification and oral antidiabetic therapy, with treatment intensification considered when glycemic targets are not achieved. Current consensus recommendations emphasize a patient-centered approach that considers cardiovascular and renal comorbidities, hypoglycemia risk, weight, cost, access, and patient preferences when selecting glucose-lowering therapy [6]. As beta-cell function progressively declines, many patients eventually require injectable therapy, including insulin, frequently in combination with oral antidiabetic agents [6,7].

However, patients receiving combined insulin plus oral antidiabetic therapy often represent a clinically different population. They frequently have longer diabetes duration, greater metabolic deterioration, higher treatment complexity, and more advanced disease. Therapeutic inertia and delays in treatment intensification may further contribute to prolonged exposure to hyperglycemia before insulin is initiated [8]. Therefore, worse glycemic control among insulin-treated patients in observational studies may reflect disease severity, treatment delay, or selection bias rather than lower treatment effectiveness.

Previous studies have identified several factors associated with poor glycemic control, including longer diabetes duration, medication adherence, body mass index (BMI), treatment complexity, and use of insulin or combined therapy [9,10]. In addition, therapeutic inertia has been described as an important barrier to timely treatment intensification in patients with T2DM [11,12]. Nevertheless, the relationship between treatment modality and glycemic control remains clinically relevant, particularly in real-world settings where treatment groups are not randomized and may differ substantially in baseline characteristics.

Understanding how treatment modality is associated with glycemic control in routine clinical practice may help identify patients at higher risk of inadequate control and support earlier therapeutic optimization. Therefore, this study aimed to evaluate the association between treatment modality and glycemic control in patients with T2DM treated at a specialized metabolic and cardiovascular center, using a retrospective cross-sectional analysis adjusted for clinically relevant variables.