Plasma Omentin-1 Level and its Relationship with Insulin Resistance in Obese Prediabetics

Abstract

Introduction: Omentin-1 is an adipokine expressed, predominantly in visceral fat and has insulin sensitising effects. However, its levels in obese prediabetics have not been evaluated so far in India. Aim: To evaluate plasma levels of omentin-1 in obese prediabetic, obese normoglycaemic and healthy individuals and to explore correlation of omentin-1 with measures of obesity and insulin resistance. Materials and Methods: The present case control study was conducted on 150 males from medical OPD of hospital. Based on anthropometrical measurements and Oral Glucose Tolerance Test (OGTT) with 75 g of anhydrous glucose, three groups of 50 males each (20-50 years) were selected. Group-1 included healthy controls, Group-2 obese normoglycaemic and Group-3 obese prediabetic subjects. Fasting and postprandial plasma glucose, HbA1c, fasting serum insulin, plasma omentin-1 and lipid profile was investigated. Insulin resistance was calculated by Homeostatic Model of Insulin Resistance (HOMA-IR). Statistical analysis was carried out by SPSS statistics software using one-way ANOVA followed by Tukey’s test at 5% level. Pearson’s correlation coefficient was used for calculation of association of variables. Results: We found that plasma omentin-1 levels were decreased significantly in obese prediabetics (228.7±13.4 ng/mL) compared to obese normoglycaemic (298.4±79.8 ng/mL) and healthy control (408.0±98.9 ng/mL) (p<0.05). Fasting insulin levels were higher in obese prediabetics (11.2±3.20 µU/mL) compared to obese normoglycaemic (8.4±4.78 µU/mL) and healthy controls (5.5±2.90 µU/mL). Obese prediabetics had altered lipid profile. HOMA-IR was higher in obese prediabetics, compared to other two groups. Plasma omentin-1 levels showed negative and significant correlation with HOMA-IR (p<0.05). Conclusion: Concentration of plasma omentin-1 decreased and insulin resistance increased in obese prediabetics compared to obese normoglycaemics and healthy controls. As omentin-1 increases sensitivity to insulin, its decreased levels may be responsible for impaired glucose homeostasis in obese prediabetics.

Keywords

• adipokine
• glucose tolerance
• lipid profile