Effect of an aqueous Russian tarragon extract on glucose tolerance in response to an oral dextrose load in non-diabetic men

Richard J Bloomer1, Robert E Canale1, Ivo Pischel21Cardiorespiratory/Metabolic Laboratory, The University of Memphis, Memphis, TN, USA; 2PhytoLab GmbH & Co. KG, Vestenbergsgreuth, GermanyBackground: Russian tarragon extracts have been reported to have anti-diabetic activity in animals. This pilot study aimed to investigate the acute effects of an aqueous extract of Russian tarragon (RT) on serum glucose and insulin in response to an oral glucose tolerance test (OGTT).Methods: Using a randomized, double-blind, cross-over design, 12 non-diabetic men reported to the lab on 2 different mornings separated by 1 to 2 weeks, and ingested 75 g of dextrose in solution. Fifteen minutes before ingestion, subjects ingested either 2 g of RT or a placebo. Blood samples were collected before ingestion of the RT and placebo, and at 15, 30, 45, 60, and 75 minutes post ingestion of the dextrose load. Samples were assayed for serum glucose and insulin.Results: For serum glucose, no condition (P = 0.19) or condition × time (P = 0.99) effect was noted. A time effect was noted (P < 0.0001), with values at 15 and 30 minutes higher than pre-ingestion (P < 0.05). No area under the curve (AUC) effect (P = 0.54) was noted, although a 4.5% reduction in AUC was observed for RT (569 ± 92 mg · dL−1 · 75 min−1) vs placebo (596 ± 123 mg · dL−1 · 75 min−1). Similar findings were noted for serum insulin, with no condition (P = 0.24) or condition × time (P = 0.98) effect noted. A time effect was noted (P < 0.0001), with values at 15, 30, and 45 minutes higher than pre-ingestion (P < 0.05). No AUC effect (P = 0.53) was noted, although a 17.4% reduction in AUC was observed for RT (114 ± 22 µIU · mL−1 · 75 min−1) vs placebo (138 ± 30 µIU · mL−1 · 75 min−1). Approximately two-thirds of subjects ingesting the RT experienced attenuation in both the glucose and insulin response to the OGTT.Conclusion: These data indicate that acute ingestion of RT results in a slight, non-statistically significant lowering of blood glucose in response to a dextrose load. This occurs in the presence of a slightly lower insulin response. These findings are specific to a small sample of healthy, non-diabetic men. Additional study is needed involving a larger sample of individuals with pre-diabetes or untreated diabetes.Keywords: Artemisia dracunculus L., glucose, insulin resistance, nutritional supplements, Russian tarragon