Absence of antihyperglycemic effect of jambolan in experimental and clinical models

The use of alternative therapies to treat diabetes, including teas prepared with different vegetables, is widespread in Brazil. In Porto Alegre, a southern city of Brazil, the tea prepared from leaves of Syzygium cumini (L.) Skeels or S. jambos (L.) Alst has been report to be used frequently by diabetic patients. We investigated the postulated antihyperglycemic effect of the S. cumini (L.) Skeels in three experiments. In the first, a randomized, parallel, placebo controlled trial, tea prepared from leaves of S. cumini did not present any antihyperglycernic effect in 30 non-diabetic young volunteers submitted to a glucose blood tolerance test. In the animal experiments, we tested the effect of increasing doses of the crude extract prepared from leaves of S. cumini administrated for 2 weeks, on the post-prandial blood glucose level of normal rats and rats with streptozotocin-induced diabetes mellitus. The treatment did not produce any antihyperglycernic effect in both models. These results do not rule out hypoglycemic effects in patients with type 2 diabetes mellitus, but strongly suggest that, for a while, the jambolan can not be recommended as an antihyperglycemic treatment.