Gymnema Sylvestre is an herb used in the Diabetic Formula of the CardioTrim health supplement line.

References:

1. Baskaran K, Kizar Ahamath B, Radha Shanmugasundaram K, Shanmugasundaram ER. Antidiabetic effect of a leaf extract from Gymnema sylvestre in non-insulin-dependent diabetes mellitus patients. J Ethnopharmacol. 1990 Oct;30(3):295-300.
2. Chattopadhyay RR. Possible mechanism of antihyperglycemic effect of Gymnema sylvestre leaf extract. Gen Pharmacol. 1998 Sep;31(3):495-6.
3. Fushiki T, Kojima A, Imoto T, Inoue K, Sugimoto E. An extract of Gymnema sylvestre leaves and purified gymnemic acid inhibits glucose-stimulated gastric inhibitory peptide secretion in rats. J Nutr. 1992 Dec;122(12):2367-73.
4. Khare AK, Tondon RN, Tewari JP. Hypoglycaemic activity of an indigenous drug (Gymnema sylvestre, 'Gurmar') in normal and diabetic persons. Indian J Physiol Pharmacol. 1983 Jul-Sep;27(3):257-8.
5. Miyasaka A, Imoto T. Electrophysiological characterization of the inhibitory effect of a novel peptide gurmarin on the sweet taste response in rats. Brain Res. 1995 Apr 3;676(1):63-8.
6. Murakami N, Murakami T, Kadoya M, Matsuda H, Yamahara J, Yoshikawa M. New hypoglycemic constituents in "gymnemic acid" from Gymnema sylvestre. Chem Pharm Bull (Tokyo). 1996 Feb;44(2):469-71.
7. Okabayashi Y, Tani S, Fujisawa T, Koide M, Hasegawa H, Nakamura T, Fujii M, Otsuki M. Effect of Gymnema sylvestre, R.Br. on glucose homeostasis in rats. Diabetes Res Clin Pract. 1990 May-Jun;9(2):143-
8. Ota M, Shimizu Y, Tonosaki K, Ariyoshi Y. Role of hydrophobic amino acids in gurmarin, a sweetness-suppressing polypeptide. Biopolymers. 1998 Mar;45(3):231-8.
9. Ota M, Shimizu Y, Tonosaki K, Ariyoshi Y. Synthesis, characterization, and sweetness-suppressing activities of gurmarin analogues missing one disulfide bond. Biopolymers. 1998 Aug;46(2):65-73.
10. Shanmugasundaram ER, Gopinath KL, Radha Shanmugasundaram K, Rajendran VM. Possible regeneration of the islets of Langerhans in streptozotocin-diabetic rats given Gymnema sylvestre leaf extracts. J Ethnopharmacol. 1990 Oct;30(3):265-79.
11. Shanmugasundaram ER, Rajeswari G, Baskaran K, Rajesh Kumar BR, Radha Shanmugasundaram K, Kizar Ahmath B. Use of Gymnema sylvestre leaf extract in the control of blood glucose in insulin-dependent diabetes mellitus. J Ethnopharmacol. 1990 Oct;30(3):281-94.
12. Shanmugasundaram KR, Panneerselvam C, Samudram P, Shanmugasundaram ER. The insulinotropic activity of Gymnema sylvestre, R. Br. An Indian medical herb used in controlling diabetes mellitus. Pharmacol Res Commun. 1981 May;13(5):475-86.
13. Shimizu K, Abe T, Nakajyo S, Urakawa N, Atsuchi M, Yamashita C. Inhibitory effects of glucose utilization by gymnema acids in the guinea-pig ileal longitudinal muscle. J Smooth Muscle Res. 1996 Oct;32(5):219-28.
14. Shimizu K, Iino A, Nakajima J, Tanaka K, Nakajyo S, Urakawa N, Atsuchi M, Wada T, Yamashita C. Suppression of glucose absorption by some fractions extracted from Gymnema sylvestre leaves. J Vet Med Sci. 1997 Apr;59(4):245-51.
15. Shimizu K, Ozeki M, Tanaka K, Itoh K, Nakajyo S, Urakawa N, Atsuchi M. Suppression of glucose absorption by extracts from the leaves of Gymnema inodorum. J Vet Med Sci. 1997 Sep;59(9):753-7.
16. Srivastava Y, Nigam SK, Bhatt HV, Verma Y, Prem AS. Hypoglycemic and life-prolonging properties of Gymnema sylvestre leaf extract in diabetic rats. Isr J Med Sci. 1985 Jun;21(6):540-2.
17. Suttisri R, Lee IS, Kinghorn AD. Plant-derived triterpenoid sweetness inhibitors. J Ethnopharmacol. 1995 Jun 23;47(1):9-26.
18. Yoshikawa M, Murakami T, Kadoya M, Li Y, Murakami N, Yamahara J, Matsuda H. Medicinal foodstuffs. IX. The inhibitors of glucose absorption from the leaves of Gymnema sylvestre R. BR. (Asclepiadaceae): structures of gymnemosides a and b. Chem Pharm Bull (Tokyo). 1997 Oct;45(10):1671-6.
19. Yoshikawa M, Murakami T, Matsuda H. Medicinal foodstuffs. X. Structures of new triterpene glycosides, gymnemosides-c, -d, -e, and -f, from the leaves of Gymnema sylvestre R. Br.: influence of gymnema glycosides on glucose uptake in rat small intestinal fragments. Chem Pharm Bull (Tokyo). 1997 Dec;45(12):2034-8.