2.1. Study Design and Subjects Selection
This is a case-control study was carried out at the College of Medicine and Health Sciences, Hadhramout University, and the subjects were selected from the diabetic outpatient clinic of Ibn-Sina hospital, Mukalla during the period from 1st January to 30th May 2020. A total of 284 Yemeni adult subjects, randomly selected, and recruited into this study. At recruitment, an in-person interview was conducted using a structured questionnaire to collect health-related information. The study group was subdivided into two groups: 142 healthy control subjects composed of 51 males and 91 females (age: 46.0±7.94 yr.), and 142 T2D patients composed of 64 males and 78 females (age: 54.0±8.29 yr.). T2D patients were those who reported being diagnosed with T2D. Healthy control subjects were selected from the remaining participants who were free of T2D and were matched for age, sex, and dialect group with cases on a 1:1 ratio. Moreover, the selected healthy control subjects were screened for the presence of undiagnosed T2D at the time of blood donation by measuring fasting blood glucose (FBG). Healthy control subjects with FBG ≥7.0mmol/L were excluded from the study. Written consent was obtained from each participant entered into the study. The study was approved by the Ethics Committee of the Medicine and Health Sciences College, Hadhramout University, Mukalla, Yemen. Patients with co-morbidities such as chronic liver disease, chronic renal disease, cardiovascular disease, and malignancy were excluded.
2.2. Data Collection
A questionnaire form focusing on demographic information and diabetes history was given to all subjects. The patient’s demographic information, clinical presentation, medical history, and physical findings were taken from each subject. This included the patient’s age, sex, smoking status (never, current or past), hypertension status (yes or no), diabetes status (yes or no) diabetes duration (years), diabetes medication, and diabetes complications. Patients were diagnosed with diabetes based on medical history, present intake of diabetes medications, or according to the American Diabetes Association (ADA) criteria [14]. Classification of Body Mass Index (BMI) was based on the World Health [15].
2.3. Anthropometric and Blood Pressure Measurements
Weight and height were measured following measured according to WHO guidelines [15]. Body mass index (BMI) was calculated as weight/height2 (Kg/m2). Obese subjects were defined as BMI ≥30 kg/m2 and normal-weight subjects having a BMI of 18–25 according to WHO guidelines [15]. Patients who had a blood pressure of ≥140/90 mmHg or were taking antihypertensive medications were diagnosed with hypertension [16]. A true healthy normal ALT level ranges from 29 to 33 IU/l for males, and 19 to 25 IU/l for females and levels above this should be assessed as described by the American College of Gastroenterology (ACG) [17].
2.3. Biochemical Investigations
Ten milliliters of the venous blood sample was obtained from consenting subjects. The blood samples were collected by vein puncture in tubes without anticoagulant. The blood samples were then transported to the laboratory immediately. The serum was separated and stored at −20°C freezers till analyses. The serum samples of matched case–control pairs were randomly placed next to each other with the case/control status blinded to the laboratory personnel and were processed, and tested in the same batch. All laboratory equipment was calibrated. Thawing freezing was avoided by dividing the samples into aliquots. Plasma fasting blood glucose (FBG), total cholesterol, triglycerides, and HDL-cholesterol (HDL-C) were determined enzymatically using a chemical autoanalyzer (Cobas Integra 400 Plus, Roche diagnostic GmbH, Mannheim, Switzerland), following the standard procedures as described by the manufacturer. Concentrations of LDL-cholesterol (LDL-C) were calculated using Friedwald's formula [18]. All biochemical investigations were analyzed in the National Center for Public Health Labs–Mukalla, Yemen.
2.4. Statistical Analysis
Data were analyzed using the Statistical Package for the Social Sciences for Windows (version 24) and are expressed by mean ± standard deviation (SD) for continuous variables (normally distributed). Non-continuous variables are expressed by median (inter-quartile range) and n (percentage) for categorical variables. Independent Student’s t-test used for normally distributed continuous variables and Wilcoxon signed-rank test for skewed continuous variables. The Pearson correlation test was performed with ALT, AST, and GGT as the dependent variables. The statistical analysis was conducted at a 95% confidence level and a P -value <0.05 was considered statistically significant.