Ethics approval and consent to participate
The Ethical Review Committee of the University of Ilorin Teaching Hospital, Kwara State Nigeria, approved the ethics. (Reference number: UITH/CAT/189/19B/120). Consent to participate was also given by individual participants.
Study Population
This cross-sectional study comprised female type 2 DM patients with or without systemic hypertension, and it was carried out at the University of Ilorin Teaching Hospital in Ilorin, Nigeria, between October and December 2020. Prior to their enrollment in the trial, every patient gave written, informed consent, and the study was approved by the institutional ethics committee. A total of 122 individuals were registered for the research.
Participants were grouped into three: group 1 (control) consists of 42 normotensive and normoglycemic subjects; group 2 consists of 40 hypertensive patients without type 2 DM while group 3 was made up of 40 hypertensive patients with type 2 DM.
Control group consisted of normotensive (≤130/80 mmHg and not on any antihypertensive medication) and normoglycemic (FBS <7 mmol/l and not on any antidiabetic medication) individuals for control group. Hypertensive group were patients with blood pressure (BP) ≥ 140/90mmHg or on antihypertensive medication. Diabetic hypertensive group had BP ≥ 140/90 mmHg, or fasting blood glucose (FBG) ≥7.0mmol/L on both antihypertensive and oral hypoglycemic medication. Physicians diagnosed hypertension based on the Joint National Committee 8 criteria, which include SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg, a history of hypertension, and use of antihypertensive medications. FBG values ≥7.0 mmol/L or a history of diabetes were used to define diabetes.
Excluded were those with secondary hypertension, patients on levothyroxine, or anti-thyroid drugs, steroid hormones, lithium, amiodarone, thiazide, thiazide-like drugs, loop diuretics, contraceptives and anticonvulsants, patients with liver or renal function impairment, systemic inflammatory disease, patients with thyroidal tumor, patients who have had thyroid surgery
Detailed information of all patients was recorded including age, anthropometric data, duration of diabetes, duration of hypertension, usage of medications, smoking and other lifestyle risk factors, and self-reported history of systemic illnesses, such as nephropathy and prior strokes.
Measurements
In order to measure their height and weight, participants had to take off their shoes and any heavy items. We measured and expressed our weight and height in kilograms and centimeters, accordingly. The formula for calculating BMI was weight (in kg) divided by height (in m2). Measurements of the waist circumference (in centimeters) and hip circumference (in centimeters) were taken at the maximum protuberance of the buttocks and the approximate midpoint between the top of the iliac crest and the lower edge of the last palpable rib at the conclusion of tidal expiration. The waist-height ratio (WHtR) was computed by dividing the waist circumference (WC) by the height, and the waist-hip ratio (WHR) was computed by dividing the WC by the hip circumference (HC). After ten minutes of rest, the right arm's blood pressure was measured twice with an automated instrument (BP7250, OMRON, Kyoto, Japan), and the average was utilized.
Blood samples were obtained for fasting plasma glucose testing following an overnight fast (FPG), glycated hemoglobin (HbA1c), serum insulin, triglycerides, thyroid hormones, electrolytes and urea.
Estimation of parameters
After collection, fasting plasma glucose and glycated hemoglobin samples were analysed immediately, while for other assays, serum was separated and aliquoted into cryovials, and stored at -80 °C for later analyses.
For each of the assayed biochemical parameters, the corresponding kit (Biobase Biodustry, High-tech Zone, Jinan, Shandong, China) was loaded into the auto analyser, samples were taken by pre-calibrated micropipette into the auto analyser and results generated. The glycated haemoglobin was determined using the glycohaemoglobin kit from Fortress diagnostics Limited UK.
The Enzyme Linked Immunosorbent Assay technique was utilized to evaluate the serum levels of TSH, free T3, free T4, and insulin (from Diagnostic Automation Inc, 21250 Califa St., Suite 102, 91367 Woodland Hills, CA).
Using the following formula, the homeostasis model of assessment for insulin resistance (HOMA-IR) was developed: Fasting plasma glucose (mmol/l) x Fasting serum insulin (mIU/l)/22.5. The formula used to calculate the Triglyceride-Glucose Index (TyG index) was Ln [fasting triglycerides (mg/dL) × fasting plasma glucose (mg/dL)/2].
Statistical analysis
With SPSS software, all statistical analyses were carried out (version 20, IBM SPSS Statistics, Chicago, IL). The presentation of continuous variables is given as mean ± standard deviations. With one-way ANOVA, statistical differences across groups were assessed. For pairwise comparison, a post hoc Bonferroni test was used. Pearson's correlation coefficient was used to estimate bivariate associations. We employed linear regression analysis to find the characteristics that predict HOMAIR. To find the best predictor of insulin resistance, the receiver operation characteristic curve's area under the curve was produced. We considered a p-value of less than 0.05 to be statistically significant.