INS and obesity due to melanocortin 4 receptor deficiency: A familial effectwas also demonstrated in Psammomys obesus, andaccounted for 51% of the variation in body weight,and 23–26% of the variation in blood glucose andplasma insulin concentrations in these animals.Psammomys obesus represents an excellent animalmodel of.obesity and Type 2 diabetes that exhibits aphenotypic pattern closely resembling that observedin human population studies.