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Expression of circulating Microrna’s (Mirnas) in blood of mixed ancestry subjects with glucose intolerance
Background: Early detection of individuals who are at risk of developing Glucose Intolerance would decrease the morbidity and mortality associated with this disease. MicroRNA is one of the most widely studied biomolecules involved in epigenetic mechanisms, hence it offers unique opportunities in this regard. Circulating microRNAs are associated with disease pathogenesis during the asymptomatic stage of disease. This has therefore attracted a lot of attention as a potential biomarker for identifying individuals who have an increased risk of developing Glucose Intolerance. The identification of high risk biomarkers for Glucose Intolerance will go a long way to eliminate the possible complications that arise due to late diagnosis and treatment of Glucose Intolerance. This could ultimately lead to better ways to prevent, manage and control the Glucose Intolerance epidemic that is rampant worldwide. The aim of the study is to investigate expression of circulating microRNA’s in blood of mixed ancestry subjects with glucose intolerance. Methods: A quantitative cross-sectional study design involving 36 individuals [who were age, gender and BMI (Body Mass Index) matched] from a total population of 1989 participants of mixed ancestry descent, residing in Bellville South, South Africa was used. Participants were classified as controls (normoglycemic), pre-diabetic (preDM) and diabetic (DM) (screen detected diabetic) according to WHO criteria of 1998. MicroRNAs were extracted from serum using the Qiagen miRNeasy Serum/Plasma Kit (ThermoFisher). The purified micro RNAs were reverse-transcribed to cDNA (complementary deoxyribonucleic acid) using the Qiagen RT2 First Strand Kit. Then, using Qiagen miScript SYBR Green PCR kit and miScript miRNA PCR arrays (ThermoFisher), the real time polymerase chain reaction was done to determine the expression profile the circulating micro RNAs present in the serum of the participants. Results: The 36 participants were evenly divided into 3 groups of 12 participants each as mentioned earlier. There were significant differences between groups in the waist (cm) (p=0.0415) and waist/hip ratio (p=0.0011) with highest values in the DM group and lowest in the normal group. Clinical parameters varied significantly according to glycemic status. As expected, the FBG (mmol/L) (p<0.0001), 2 HRs Post Glucose (mmol/L) (p<0.0001), HbA1c (%) (p=0.0009), Fasting Insulin (mIU/L) (p=0.0039), were all highest in the DM and lowest in the control group. In contrast, the 2 HRs Post Insulin (mIU/L) (p = 0.0027) was highest in the preDM group and lowest in the normal group, while the Glucose/Insulin ratio (p=0.0477) was highest in the normal group and lowest in the preDM group. Triglycerides (mmol/L) (p=0.0043) and Total Chol (mmol/L) (p=0.0429) were significantly increased through the three groups, with highest values in the DM group and lowest in the normal group. Furthermore, 12 of the 84 miRNAs studied were expressed through all the 3 groups and they exhibited both inverse and positive correlations between the clinical parameters, especially the glucose parameters (Fasting blood glucose, 2 hours post glucose, Fasting blood insulin, 2 hours post insulin and Glycated Hemoglobin).