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.
Insulin analog shifted isoelectric point so that they exist in a solubility equilibrium in which most precipitates out but slowly dissolves in the bloodstream and is eventually excreted by the kidneys. These insulin analogues are used to replace the basal level of insulin, and may be effective over a period of up to 24 hours. However, some insulin analogues, such as insulin detemir, bind to albumin rather than fat like earlier insulin varieties, and results from long-term usage (e.g. more than 10 years) are currently not available but required for assessment of clinical benefit. Unmodified human and porcine insulins tend to complex