Serum Retinol Binding Protein-4 Levels in Prediabetics - Novel Biomarker of Insulin Resistance and Atherosclerosis.

Background: Atherosclerotic cardiovascular diseases are the leading cause of morbidity and mortality in both diabetics and prediabetics. In insulin resistant states, increased levels of various adipose derived cytokine (adipokine) have been found to have an important role in the process of atherosclerosis. One such novel adipokine is RBP4, (belonging to lipokalin family) which also by exerting an inflammatory process has a role in the pathogenesis of insulin resistance and CVD.. Early detection of all these inflammatory cytokines may immensely help us in prognosticating the pace of disease besides instituting early interventional manuevers.

Objective: The aim of the study was to compare serum levels of RBP4 in prediabetics and controls and to correlate levels of RBP4 with HOMA-IR and CIMT.

Methods: 60 prediabetic patients and 60 age, sex, BMI matched controls were employed in the case control study. In both cases and controls serum levels of fasting and postprandial blood glucose, glycated hemoglobin (HbA1c) and fasting insulin levels were measured. HOMA-IR values in both the groups were calculated using fasting glucose and insulin levels. Serum RBP4 levels were measured using ELISA. The values obtained were compared between cases and controls. CIMT was only measured in cases using B-mode ultrasonography.

Results: Median (IQR) of fasting plasma insulin levels (uIU/ml)in cases was 11.3 (10.175-13.505) versus that of controls which was 5.73 (4.3-7.1). HOMA-IR median (IQR) in cases and controls was 3.12 (2.73-3.595) and 1.21(0.918-1.505) respectively. Median (IQR) for RBP4 in cases was 67.4 (46.166-111.088) which was significantly higher as compared to controls 33.92 (23.902-52.45). Significant positive correlation was seen between RBP4 with both, HOMA-IR and mean CIMT with correlation coefficients of 0.3693 and 0.621 respectively. On performing univariate linear regression analysis it was found that with increase in serum RBP4 levels by 1 mg/L, HOMA-IR and mean CIMT significantly increased by 0.007 units and 0.001 mm respectively.

Methods: 60 prediabetic patients and 60 age, sex, BMI matched controls were employed in the case control study. In both cases and controls serum levels of fasting and postprandial blood glucose, glycated hemoglobin (HbA1c) and fasting insulin levels were measured. HOMA-IR values in both the groups were calculated using fasting glucose and insulin levels. Serum RBP4 levels were measured using ELISA. The values obtained were compared between cases and controls. CIMT was only measured in cases using B-mode ultrasonography.

Conclusion: Prediabetics have been found to have more risk of cardiovascular events as compared to normoglycemics. Early assessment of the same with the use of novel biomarkers like RBP4 can be considered for early detection of atherosclerosis in prediabetic individuals. It may further help in early intervention and thus prevention from future complications.