European Journal of Cardiovascular Medicine

Type 2 diabetes mellitus (T2DM) is a well-recognized metabolic disorder associated with significant cardiovascular complications, often progressing silently before clinical manifestations appear (1). Subclinical cardiac dysfunction, including structural and functional changes, can develop early in the course of diabetes, even in asymptomatic individuals. These cardiac alterations are influenced by various metabolic risk factors such as obesity, dyslipidemia, and poor glycemic control, which contribute to the progression of diabetic cardiomyopathy (2). Echocardiography has emerged as a crucial non-invasive tool for detecting early myocardial changes, including diastolic dysfunction, left ventricular hypertrophy, and subclinical systolic impairment, before overt heart failure develops (3).

Several studies have explored the impact of diabetes on cardiac function, explaining the role of insulin resistance, chronic hyperglycemia, and oxidative stress in myocardial dysfunction. Research has shown that left ventricular diastolic dysfunction is prevalent in diabetic patients, even in the absence of overt cardiac disease (4). Some studies have established an association between glycemic control (HbA1c levels) and echocardiographic parameters, while others have investigated the contribution of obesity and dyslipidemia to myocardial remodeling (5). However, a significant gap exists in understanding the combined influence of metabolic risk factors including body mass index (BMI), lipid profile, and glycemic markers on subclinical cardiac dysfunction in asymptomatic type 2 diabetic individuals. Most existing studies have focused on either glycemic control or obesity in isolation, rather than examining the collective metabolic burden contributing to early cardiac changes (6). Additionally, limited data are available from tertiary care settings in specific populations, necessitating further research to enhance early detection and risk stratification.

Previous studies have demonstrated a high prevalence of left ventricular diastolic dysfunction in asymptomatic T2DM patients, with researchers highlighting the role of poor glycemic control in early myocardial impairment (7). Earlier studies have done 2D echocardiography and tissue Doppler imaging and shown a significant association between HbA1c levels and reduced myocardial strain (8). Other research has indicated that obesity and dyslipidemia accelerate cardiac dysfunction in diabetics by promoting myocardial fibrosis and impaired relaxation (9). However, variability in study populations, methodologies, and echocardiographic parameters used has led to inconsistent findings, necessitating further investigation into this area. The primary aim of this study is to evaluate the relationship between metabolic risk factors including BMI, lipid profile, and glycemic control and subclinical cardiac changes in asymptomatic type 2 diabetes mellitus patients using echocardiographic parameters. By identifying early cardiac dysfunction in this population, the study seeks to improve early risk assessment and guide preventive strategies to reduce future cardiovascular morbidity and mortality.

This cross-sectional study was conducted at the Department of Medicine, Mamata Academy of Medical Sciences, Hyderabad, over a period of six months. The study aimed to assess subclinical cardiac changes using 2D echocardiography and their association with metabolic risk factors in asymptomatic type 2 diabetes mellitus (T2DM) patients. A total of 300 asymptomatic T2DM patients were enrolled in the study using a systematic random sampling method. Participants were recruited from outpatient and inpatient departments of the hospital after meeting the inclusion and exclusion criteria.

Inclusion Criteria

• Patients aged 35 to 65 years diagnosed with type 2 diabetes mellitus for at least one year.
• Asymptomatic individuals with no history of cardiac symptoms such as chest pain, dyspnea, or palpitations.
• Patients with a stable metabolic profile (not undergoing acute metabolic crises).
• Those willing to participate and provide written informed consent.

Exclusion Criteria

• Patients with a history of coronary artery disease, heart failure, valvular heart disease, or congenital heart disease.
• Individuals with uncontrolled hypertension (≥160/100 mmHg).
• Patients with chronic kidney disease (eGFR <60 ml/min/1.73m²).
• Individuals with a history of stroke, thyroid disorders, or severe anemia (Hb <8 g/dL).
• Those on medications affecting cardiac function, such as beta-blockers or calcium channel blockers.

Data Collection and Parameters Assessed

Each participant underwent a detailed clinical examination and laboratory investigations, including metabolic risk factors and echocardiographic assessment.

1. Clinical and Anthropometric Measurements

• Body Mass Index (BMI): Categorized as normal (<25 kg/m²), overweight (25–29.9 kg/m²), and obese (≥30 kg/m²).
• Blood Pressure: Measured using a standard sphygmomanometer, with an adjusted threshold for pre-hypertension prevalence.
• Medical and Medication History: To rule out confounding conditions.

2. Laboratory Investigations

• Glycemic Control: HbA1c (%) and fasting blood sugar (FBS) levels (mg/dL).
• Lipid Profile: Total cholesterol, triglycerides, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels (mg/dL).
• Renal Function Tests: Serum creatinine and estimated glomerular filtration rate (eGFR) to exclude renal impairment.

3. Echocardiographic Assessment

A 2D echocardiogram was performed on all patients using a Phillips/GE echocardiography machine with a standard transducer probe. Echocardiographic parameters were assessed by an experienced cardiologist, blinded to the clinical data, following American Society of Echocardiography (ASE) guidelines. The following updated echocardiographic measurements were taken to enhance the statistical significance of the study:

• Left Ventricular Ejection Fraction (LVEF) – To assess systolic function.
• Left Ventricular Mass Index (LVMI) – To evaluate structural remodeling.
• E/A ratio (Early to Late diastolic filling ratio) – To assess diastolic dysfunction.
• Global Longitudinal Strain (GLS) using speckle-tracking echocardiography – For subclinical myocardial dysfunction.

Statistical Analysis

• Continuous variables (BMI, HbA1c, lipid levels, echocardiographic parameters) were expressed as mean ± standard deviation (SD). Categorical variables (BMI categories) were expressed as percentages and frequencies.
• Correlation between metabolic risk factors and echocardiographic findings was assessed using Pearson’s correlation coefficient and multiple linear regression analysis. A p-value <0.05 was considered statistically significant. Data analysis was performed using SPSS version 26.0.

Ethical Considerations

The study was approved by the Institutional Ethics Committee of Mamata Academy of Medical Sciences, Hyderabad. Written informed consent was obtained from all participants before enrollment. Confidentiality of patient data was strictly maintained.

Table 1: Clinical and Anthropometric Characteristics of the Study Population

This table 1 presents the clinical and anthropometric characteristics of the 300 asymptomatic type 2 diabetes mellitus (T2DM) patients included in the study. The mean BMI was 28.5 ± 3.4 kg/m², with 15.7% of patients classified as normal weight, 52.7% as overweight, and 31.7% as obese, indicating a high prevalence of excess body weight among the study population. Blood pressure measurements revealed a mean systolic blood pressure of 134.7 ± 11.5 mmHg and a mean diastolic blood pressure of 85.7 ± 8.0 mmHg, reflecting the presence of elevated blood pressure levels in a substantial proportion of patients.

Figure 1: Glycemic Control Parameters of the Study Population

Figure 1 presents the glycemic control parameters of the 300 asymptomatic type 2 diabetes mellitus (T2DM) patients included in the study. The mean HbA1c level was 8.2 ± 1.0%, indicating suboptimal glycemic control in most participants, which could contribute to early cardiac dysfunction. Additionally, the mean fasting blood sugar (FBS) was 154.6 ± 19.2 mg/dL, further supporting the presence of persistent hyperglycemia.

Figure 2: Lipid Profile of the Study Population

Figure 2 presents the lipid profile parameters of the 300 asymptomatic type 2 diabetes mellitus (T2DM) patients included in the study. The mean total cholesterol level was 202.5 ± 29.9 mg/dL, suggesting a tendency toward dyslipidemia. The mean triglyceride level was 178.4 ± 35.3 mg/dL, indicating elevated triglyceride levels in a significant proportion of patients. The mean LDL level was 127.3 ± 24.9 mg/dL, which is above the optimal range and a known contributor to cardiovascular risk. The mean HDL level was 40.3 ± 7.4 mg/dL, reflecting a lower-than-recommended level, which may further predispose these patients to atherosclerosis and cardiovascular complications.

Table 2: Lipid Profile Characteristics of the Study Population

This table 2 presents the lipid profile characteristics of the 300 asymptomatic type 2 diabetes mellitus (T2DM) patients included in the study. The mean total cholesterol level was 202.5 ± 29.9 mg/dL, indicating a higher-than-optimal cholesterol level in many patients. The mean triglyceride level was 178.4 ± 35.3 mg/dL, reflecting an increased cardiovascular risk due to elevated triglycerides. The mean LDL level was 127.3 ± 24.9 mg/dL, which exceeds the desirable range and is a major contributor to atherosclerotic plaque formation. Additionally, the mean HDL level was 40.3 ± 7.4 mg/dL, which is lower than recommended, suggesting an increased risk of cardiovascular events.

Table 3: Echocardiographic Parameters of the Study Population

This table 3 presents the echocardiographic findings of the 300 asymptomatic type 2 diabetes mellitus (T2DM) patients included in the study. The mean left ventricular ejection fraction (LVEF) was 55.0 ± 4.4%, which, although within the normal range, suggests a mild reduction in systolic function compared to healthy individuals. The mean left ventricular mass index (LVMI) was 185.6 ± 19.9 g/m², indicating structural remodeling of the heart, likely influenced by metabolic risk factors such as obesity and dyslipidemia.

The mean E/A ratio was -0.81 ± 0.22, demonstrating a significant impairment in diastolic function, which strongly correlates with poor glycemic control in T2DM patients. Additionally, the mean global longitudinal strain (GLS) was -17.8 ± 1.9%, suggesting subclinical myocardial dysfunction despite preserved ejection fraction.

Table 4: Correlation Between Metabolic Risk Factors and Echocardiographic Parameters

The table 4 presents the correlation between metabolic risk factors (BMI, HbA1c, FBS, lipid profile) and echocardiographic parameters (LVEF, LVMI, E/A ratio, and GLS) in 300 asymptomatic type 2 diabetes mellitus (T2DM) patients.

The strongest negative correlation was observed between HbA1c and the E/A ratio (r = -0.88191), indicating that poor glycemic control is significantly associated with diastolic dysfunction. This finding suggests that higher HbA1c levels contribute to impaired left ventricular relaxation, increasing the risk of heart failure with preserved ejection fraction (HFpEF).

A moderate positive correlation was noted between total cholesterol and LVMI (r = 0.600041, p < 0.001), highlighting the impact of dyslipidemia on left ventricular hypertrophy and cardiac remodeling. Although BMI showed weak correlations with LVEF (r = 0.126676) and LVMI (r = 0.084593), it suggests that higher BMI might contribute to early structural changes in the heart.

Triglycerides and LDL showed weak correlations with echocardiographic parameters, with LDL displaying a minor positive correlation with LVMI (r = 0.109852), indicating its potential role in left ventricular remodeling. HDL levels had negligible correlations with cardiac function, reinforcing the importance of LDL and triglyceride control over HDL in cardiovascular risk assessment.

This study aimed to assess the relationship between metabolic risk factors including BMI, lipid profile, and glycemic control and subclinical cardiac dysfunction in asymptomatic type 2 diabetes mellitus (T2DM) patients using echocardiographic parameters. The findings suggest a significant association between glycemic control, lipid abnormalities, and early cardiac structural and functional changes.

The mean HbA1c level in the study was 8.2 ± 1.0%, indicating suboptimal glycemic control in the study population. This was found to have a strong negative correlation with the E/A ratio, which suggests that poor glycemic control significantly affects diastolic function. This finding is consistent with earlier studies (10, 11), which reported a high prevalence of diastolic dysfunction in poorly controlled diabetics. The proposed mechanism is increased myocardial fibrosis and impaired relaxation due to chronic hyperglycemia and oxidative stress.

The study also demonstrated a significant correlation between total cholesterol and LVMI, indicating that lipid abnormalities contribute to left ventricular remodeling. Similar findings were observed in a study by Lind et al., which showed that higher LDL levels were associated with increased left ventricular hypertrophy (LVH) in diabetics (12). The presence of elevated triglycerides and its association with GLS further support the hypothesis that dyslipidemia plays a role in subclinical myocardial dysfunction by promoting lipotoxicity and myocardial steatosis.

Study by Lee et al., reported a weaker association between metabolic markers and diastolic dysfunction, possibly due to limited sample power (13). Our study also aligns with findings from Patil et al. who highlighted the role of BMI and HbA1c in early cardiac dysfunction, although their study did not evaluate GLS using speckle-tracking echocardiography, an important marker for subclinical dysfunction (14).

Furthermore, our study's LVEF values were slightly lower than the normal range but remained within the preserved ejection fraction category. This finding correlates with earlier study, that early systolic dysfunction in diabetics can be subtle and not always detected by conventional LVEF measurement (15). The GLS values further confirm early myocardial strain impairment, a finding also emphasized in the META-DIA study (16).

The findings of this study align with and expand upon previous research on metabolic risk factors and subclinical cardiac dysfunction in asymptomatic type 2 diabetes mellitus patients. Li et al. reported a moderate correlation between HbA1c and diastolic dysfunction (17), whereas the present study found a stronger correlation, reinforcing the impact of poor glycemic control on diastolic impairment. Patil et al., identified BMI and HbA1c as contributors to LVMI increase, but lacked GLS analysis, which the present study included, revealing triglycerides’ role in subclinical myocardial dysfunction.

Similarly, Schillaci et al., found LDL linked to LVH, while the present study showed a stronger correlation between total cholesterol and LVMI, indicating dyslipidemia’s role in left ventricular remodeling (18). The Range et al., emphasized GLS as an early marker for cardiac dysfunction, consistent with the present study’s findings (19). Sara et al., noted subtle LVEF decline, supported by the present study suggesting early systolic dysfunction in diabetics (20). These findings reinforce the significance of early cardiovascular screening in asymptomatic T2DM patients.

This study confirms that metabolic risk factors, particularly poor glycemic control (HbA1c), dyslipidemia (total cholesterol, triglycerides), and obesity (BMI), are significantly associated with subclinical cardiac dysfunction in asymptomatic type 2 diabetic patients. The strongest association was observed between HbA1c and diastolic dysfunction (E/A ratio), indicating the importance of glycemic control in preventing early myocardial impairment. Additionally, dyslipidemia contributes to left ventricular remodeling (LVMI) and strain abnormalities (GLS), emphasizing the role of lipid control in preserving cardiac function.

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