It's claimed here that garcinia cambogia extract (it's wrongly spelled here) is good for diabetics. Hardly. That claim is made by predominantly people who sell that diet product. The research shows that this product is most likely going to increase the risk of diabetes in those taking it and is going to make the disease worse in diabetics - see the scholarly report at Do Garcinia Cambogia Side Effects Boost Diabetes?
Some of the physiological processes garcinia cambogia is accomplishing that overlap with statin drugs which are clearly implicated with a significant increased risk of diabetes because both products inhibit the production of cholesterol.