INS and type 1 diabetes mellitus: Dogs suffer mostly from type 1 diabetes (DT1, in humans, often regarded as insulin dependent, early onset, autoimmune destruction of β-cells), whereas cats suffer mostly from type 2 diabetes (DT2, late-onset, insulin insensitivity); finally, type 3 (DT3, insulin resistance due to other disorders or drugs) and type 4 (DT4, gestational induced) are significantly less common in pets [1,2,4].