Insulin the simplest unicellular eukaryotes. Apart from animals, insulin-like proteins are also known to exist in the Fungi and Protista kingdoms. Insulin is produced by beta cells of the pancreatic islets in most vertebrates and by the Brockmann body in some teleost fish. Cone snails "Conus geographus" and "Conus tulipa", venomous sea snails that hunt small fish, use modified forms of insulin in their venom cocktails. The insulin toxin, closer in structure to fishes' than to snails' native insulin, slows down the prey fishes by lowering their blood glucose levels. The preproinsulin precursor of insulin is encoded by the "INS" gene.
Lifestyle causes of diabetes mellitus type 2 that "produce fewer and smaller mitochondria than is normal," and are thus prone to insulin resistance. Fat tissue has also been shown to be involved in managing much of the body's response to insulin and control of uptake of sugar. It secretes RBP4 which increases insulin resistance by blocking the action of insulin in muscle and liver. Fat cells also secrete adiponectin which acts in an opposite way to RBP4 by improving the action of insulin, however, engorged fat cells secrete it in lower amount than normal fat cells. The obese therefore may have higher level of RBP4 but lower