A recent paper noted that a substantial downregulation of the genes NKX2-1 and TPD52L3 forces an increase in the release of free fatty acids into the blood circulation and leads to a reduction in the unsaturation index (the number of carbon-carbon double bonds per 100 acyl chains of membrane phospholipids), as demonstrated in gestational diabetes mellitus, impaired glucose tolerance, and type 2 diabetes. These observations suggest that a lower unsaturation index would reduce the rate of glucose transport across the cell membrane and initiate the onset of type 2 diabetes mellitus. Surprisingly, in 1991, Pelikánová and co-workers reported that a group of 21 men with mild to moderate type 2 diabetes were treated only with a diet with an essentially increased unsaturation index. The present report describes the role of arachidonic acid in this process and provides a comprehensive update on recent developments in type 2 diabetes mellitus-related biochemistry and molecular biology that can be applied to precision medicine.