Increased C3 has been related to body mass index (BMI) and insulin resistance, although there are not sufficient studies in subjects with morbid obesity. The purpose of this study was to evaluate the levels of C3 as a function of the BMI in subjects of both sexes, with severe, morbid and extreme obesity, and their possible relationship to insulin resistance or associated diseases such as diabetes, hypertension and dyslipidemia.
The study included a total of 316 patients (110 men and 206 women) with severe obesity (17.1%), morbid obesity (54.4%) and extreme obesity (28.4%), with an average BMI of 46.70+/-7.37 kg/m2.
The glucose and insulin levels were determined baseline, and 2 h after a 75 g of oral glucose load. The homeostasis model of assessment for insulin resistance (HOMA-IR) was calculated. A lipid profile (total cholesterol, triglycerides, high-density lipoprotein cholesterol, apolipoprotein AI and apolipoprotein B100) was obtained and C3 levels determined by nephelometry.
When distributing the patients by quartiles of BMI, we found a progressive increase in the levels of C3, and no significant differences in the rest of analytical variables studied were found; the mean values of C3 were 127.78+/-29.7 mg/dl.A significant correlation was found between C3 and the BMI (r=0.263, P<0.001), baseline insulin (r=0.237, P=0.001) and HOMA-IR (r=0.237, P=0.001). High blood pressure was found in 111 patients, type 2 diabetes in 74 patients and dyslipidemia in 139 cases. When distributing the levels of C3 according to the number of associated risk factors (hypertension, diabetes and dyslipidemia), we found significant differences between these patients and those who presented no associated diseases (P<0.01).
A relationship between C3 and the progressive increase of BMI in subjects with severe, morbid or extreme obesity was established. This increase in C3 was closely related to insulin levels and the values for HOMA-IR. Furthermore, we also found an increase in C3 as more diseases related to insulin resistance, such as diabetes, hypertension and dyslipidemia, were associated with the obesity.