European Journal of Cardiovascular Medicine

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia due to defective insulin secretion, insulin action, or both. It has emerged as a global health concern, with an estimated 537 million adults living with diabetes worldwide, a figure projected to rise to 783 million by 2045 (1). Type 2 diabetes mellitus (T2DM) is the most prevalent form, constituting approximately 90% of all diabetes cases. Management of T2DM primarily involves lifestyle modifications, oral antidiabetic drugs (OADs), and in advanced cases, insulin therapy (2).

Critically ill patients with T2DM admitted to the Intensive Care Unit (ICU) often face disruptions in their usual antidiabetic treatment regimen due to factors such as fasting for procedures, altered drug metabolism, and potential drug interactions (3). As a result, OADs are frequently discontinued upon ICU admission, with insulin therapy commonly initiated for glycemic management. However, the abrupt discontinuation of OADs and transition to insulin therapy can significantly impact glycemic control, which is a critical aspect of managing critically ill patients (4).

Poor glycemic control in the ICU has been associated with increased morbidity, mortality, prolonged ICU stay, and higher healthcare costs (5). It is well-documented that hyperglycemia, even in non-diabetic patients, is associated with adverse outcomes, including increased risk of infections, impaired wound healing, and higher rates of organ failure (6). Therefore, achieving optimal glycemic control in diabetic patients admitted to the ICU remains a crucial component of patient management.

Several studies have explored the outcomes of insulin therapy in critically ill patients with T2DM; however, limited data exist regarding the impact of OAD discontinuation on glycemic control during ICU admission (7,8). Furthermore, the type of OADs used before admission may influence glycemic outcomes, as different classes of drugs exhibit varying mechanisms of action and efficacy profiles (9).

This prospective cohort study aims to evaluate the impact of OAD discontinuation on glycemic control in ICU patients with T2DM and identify factors associated with poor glycemic control during hospitalization. The findings of this study may contribute to the development of standardized protocols for the management of hyperglycemia in critically ill patients with pre-existing diabetes.

Study Design and Setting

This prospective cohort study was conducted over a 6-month period at the Intensive Care Unit (ICU) of a tertiary care hospital. The study aimed to evaluate the impact of discontinuing oral antidiabetic drugs (OADs) on glycemic control in critically ill patients with type 2 diabetes mellitus (T2DM).

Study Population

The study included adult patients aged 18 years and above, with a confirmed diagnosis of T2DM, who were admitted to the ICU and had their OADs discontinued upon admission. Patients receiving insulin therapy prior to ICU admission, those with type 1 diabetes mellitus, pregnant women, and patients with severe liver or renal dysfunction were excluded from the study.

Sample Size Calculation

A total of 200 patients were enrolled based on convenience sampling. The sample size was determined to provide sufficient statistical power to detect significant differences in glycemic control parameters among various OAD groups.

Data Collection

Data were collected from patient medical records and direct observation. Baseline characteristics such as age, gender, duration of diabetes, comorbid conditions, type of OADs used prior to admission, and glycemic control parameters (HbA1c levels) were recorded at the time of admission.

During the ICU stay, blood glucose levels were monitored at regular intervals using a standardized glucometer. The frequency of blood glucose monitoring was determined by the patient's clinical condition and institutional protocols. Insulin therapy was initiated and adjusted as necessary to maintain blood glucose levels within the target range, following standard ICU glycemic management guidelines.

Outcome Measures

The primary outcome measure was glycemic control, assessed by:

• Mean blood glucose levels during the ICU stay.
• HbA1c levels recorded at the time of admission and discharge.
• Proportion of patients achieving target blood glucose levels (140–180 mg/dL).
• Incidence of hyperglycemia (blood glucose >200 mg/dL) and hypoglycemia (blood glucose <70 mg/dL).

Secondary outcome measures included the duration of ICU stay and mortality rates.

Statistical Analysis

Data analysis was performed using statistical software (e.g., SPSS, Version 27.0). Descriptive statistics were calculated for demographic variables, comorbidities, and glycemic control parameters. Continuous variables were presented as mean ± standard deviation (SD), while categorical variables were expressed as frequencies and percentages.

Comparative analysis between different OAD groups was performed using independent t-tests or ANOVA for continuous variables and chi-square tests for categorical variables. Multivariate regression analysis was conducted to identify factors associated with poor glycemic control. A p-value of <0.05 was considered statistically significant

Baseline Characteristics

A total of 200 patients with type 2 diabetes mellitus (T2DM) were included in the study. The mean age of the patients was 58.4 ± 12.5 years, with 120 males (60%) and 80 females (40%). The majority of patients (70%) were on a combination of OADs prior to ICU admission, while the remaining 30% were on monotherapy. The baseline characteristics of the study population are summarized in Table 1.

Table 1: Baseline Characteristics of Study Population

Glycemic Control During ICU Stay

Blood glucose levels were monitored daily during the ICU stay. The mean blood glucose level for all patients during the ICU stay was 198.4 ± 45.2 mg/dL. Patients previously managed with sulfonylureas exhibited the highest mean blood glucose levels (218.5 ± 40.3 mg/dL), followed by those on metformin (205.1 ± 38.9 mg/dL), DPP-4 inhibitors (190.3 ± 35.4 mg/dL), and SGLT-2 inhibitors (182.6 ± 32.8 mg/dL). The comparison of glycemic control based on previous OAD usage is shown in Table 2.

Table 2: Comparison of Glycemic Control Based on Previous OAD Usage

Outcomes of Glycemic Control

Out of the 200 patients, 150 (75%) required insulin therapy during their ICU stay. Among these, 90 (60%) achieved target blood glucose levels (140–180 mg/dL), while 60 (40%) had persistent hyperglycemia (>200 mg/dL). The incidence of hypoglycemia was low, affecting only 10 patients (5%).

Patients with good glycemic control had an average ICU stay of 8.2 ± 2.5 days, whereas those with poor glycemic control had a significantly longer stay of 12.4 ± 3.6 days (Table 3).

Table 3: Clinical Outcomes Based on Glycemic Control

The findings from the statistical analysis revealed that poor glycemic control was significantly associated with longer ICU stay (p < 0.01) and higher mortality rates (p < 0.05).

The findings of this study highlight the challenges of managing glycemic control in critically ill patients with type 2 diabetes mellitus (T2DM) admitted to the Intensive Care Unit (ICU). The abrupt discontinuation of oral antidiabetic drugs (OADs) and the initiation of insulin therapy are essential for achieving adequate glycemic control, but the process is often associated with fluctuations in blood glucose levels (1).

The mean blood glucose levels observed in this study (198.4 ± 45.2 mg/dL) are consistent with previous studies indicating that critically ill patients with pre-existing diabetes often experience hyperglycemia during ICU admission (2,3). Hyperglycemia in critically ill patients is known to be associated with increased morbidity, prolonged ICU stay, and higher mortality rates (4). Furthermore, hyperglycemia has been linked to poor clinical outcomes due to its effects on immune function, increased risk of infection, and impaired wound healing (5,6).

Our findings indicate that patients previously managed with sulfonylureas exhibited the highest mean blood glucose levels (218.5 ± 40.3 mg/dL) during ICU stay compared to those on other OADs. This observation aligns with previous research suggesting that sulfonylurea-treated patients may experience greater glycemic instability upon discontinuation (7). Additionally, patients on metformin and DPP-4 inhibitors showed comparatively better glycemic control, which may be attributed to their unique mechanisms of action that involve reducing hepatic glucose production and enhancing insulin sensitivity (8,9).

Insulin therapy was initiated in 75% of the study population, with 60% of those achieving adequate glycemic control (blood glucose levels between 140–180 mg/dL). The use of insulin remains the standard of care for managing hyperglycemia in critically ill patients, as recommended by various guidelines (10,11). However, achieving optimal glycemic control is challenging, particularly in patients who are critically ill and have multiple comorbidities (12).

The prolonged ICU stay observed in patients with poor glycemic control (12.4 ± 3.6 days) compared to those with good control (8.2 ± 2.5 days) underscores the importance of effective glycemic management strategies (13). Studies have shown that hyperglycemia can contribute to adverse outcomes by promoting oxidative stress, inflammation, and endothelial dysfunction (14). Additionally, increased mortality rates observed among patients with poor glycemic control (15%) compared to those with good control (5%) further highlight the clinical implications of inadequate glycemic management (15).

This study demonstrates that discontinuation of oral antidiabetic drugs (OADs) in ICU patients with type 2 diabetes mellitus significantly impacts glycemic control, particularly among those previously managed with sulfonylureas. Insulin therapy initiation was necessary for most patients to achieve adequate glycemic control, although many still experienced hyperglycemia during their ICU stay. Effective glycemic management strategies are essential to reduce ICU stay duration and improve patient outcomes. Future studies should focus on optimizing transition protocols from OADs to insulin therapy in critically ill patients to enhance clinical outcomes.

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