Effect of soy protein isolate supplementation on insulin resistance, fasting blood glucose and lipid profile in type 2 diabetic outpatients at public health center 66, health department, Bangkok metropolitan administration

Abstract

This quasi-experimental study was conducted to determine the effects of soy protein isolate (SPI) supplementation on insulin resistance, fasting glucose and lipid profile in type 2 diabetic outpatients at Public Health Center 66. The duration of the study was 10 weeks with 2 periods: a 4-week dietary counseling period and a 6-week supplementation period. Thirty-eight subjects participated in this study and were randomly assigned into SPI group (supplemented with 30 g/day of SPI containing 32 mg of isoflavones) and control group (no SPI supplementation). Fasting blood biochemistry, body weight, height, and anthropometry were examined before and after the SPI supplementation period. The results showed that there was no significant difference in fasting plasma glucose, glycosylated hemoglobin (HbA1c), and insulin resistance (assessed by the HOMA-IR model) between SPI and control group. Fasting plasma glucose in control group was significantly increased (p=0.03), whereas HbA1c level in SPI group was significantly decreased (p=0.01) from baseline. The reduction of HOMA-IR was larger in the SPI group than that in the control group. No significant differences were found between groups for serum lipid profile. The concentration of TC, LDL-C, and TG were decreased greater in SPI group than those in control group. TC was significantly decreased from baseline in the subjects of the SPI group with baseline TC higher than 5.18 mmol/l (200 mg/dl) (p=0.04). There were no significant differences in weight, BMI and anthropometric data after SPI supplementation between groups and within group. This study indicated that SPI with isoflavones supplementation improves glucose control, insulin resistance and lipid profile in type 2 diabetes.