Preparation of Polylactic Acid/Glycolic Acid Copolymer Nanoparticles and Its Effect in the Treatment of Diabetes

Insulin (INS) is easily degraded when administered orally and loading it into polylactic acid/glycolic acid (PLGA) polymer nanoparticles can enhance the efficacy of the drug. The W/O/W double emulsion solvent volatilization method was adopted to prepare INS-loaded PLGA nanoparticles. The preparation formula of nanoparticles was determined according to the type, concentration, and PLGA concentration of the emulsifier. Then, the morphology, particle size, and drug encapsulation efficiency of nanoparticles were characterized. Phosphate buffered solution (PBS) with pH = 7.4 was utilized as the release medium, and the prepared nanoparticles were analyzed for in vitro release performance. In addition, the rat diabetes model was constructed, and subcutaneous injection of nanoparticle in vitro release solution was performed to observe its hypoglycemic effect, which was used for the treatment of diabetic patients. Patients were rolled into experimental group and control group. The changes of the patients’ HbA1c, blood lipids (total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)), C peptide, and aminopeptidase N (APN) were observed before and after treatment. Through the test, the appearance of the prepared nanoparticles was round, the average particle size was 416.7 nm, and the INS encapsulation efficiency was (36.82±2.26)%. After 36 h, the cumulative release of INS reached (60.58 ±1.45)%, and then the release rate gradually slowed down. The drug release tended to be balanced after 72 h, and the best hypoglycemic effect was achieved after subcutaneous administration 3 h (P < 0.01). The blood glucose level of the rat diabetes model was greatly decreased after 3 h injection of 36.8 IU/kg PLGA polymer nanoparticles (P < 0.05), and the blood glucose dropped to the lowest at 8 h (P < 0.01), which was only (38.8 ± 3.72)% of the initial blood glucose. HbA1C of diabetic patients increased remarkably after treatment (P < 0.05), TG, TC, and LDL-C in blood lipids decreased, and HDL-C increased, without statistically considerable differences (P > 0.05). The serum APN level increased greatly (P < 0.01). In short, the prepared PLGA polymer nanoparticles can effectively reduce blood glucose, help diabetic patients to relieve the toxicity of high glucose in the body, and improve the secretion function of INS.