Administration on glycemic control, insulin secretion, and insulin sensitivity in patients with impaired glucose tolerance 

This 2020 randomized, double-blind, placebo-controlled clinical trial was conducted in 30 patients with impaired glucose control. Fifteen patients were given 300 mg of G. sylvestre or placebo twice a day. Outcomes measured were related to glycemic control, insulin secretion, and insulin sensitivity using a 2-h oral glucose tolerance test (2-h OGTT), fasting plasma glucose, glycated hemoglobin A1c (A1C), and the lipid profile panel. Researchers found that at the end of the intervention, 46.7% of the patients obtained normal values in A1C, decreased 2-h OGTT and increased insulin sensitivity. 

References:

Gaytán Martínez LA, Sánchez-Ruiz LA, Zuñiga LY, González-Ortiz M, Martínez-Abundis E. Effect of Gymnema sylvestre Administration on Glycemic Control, Insulin Secretion, and Insulin Sensitivity in Patients with Impaired Glucose Tolerance. J Med Food. 2020 May 27. doi: 10.1089/jmf.2020.0024. Epub ahead of print. PMID: 32460589. https://europepmc.org/article/med/28459647