The study evaluated participants who were similar in sex and age, with a large intentional difference in the lean and obese subgroups regarding BMI, and a fairly long mean duration of type 2 diabetes of 7.5 years, thus providing a sound basis for evaluating the effect of both obesity and type 2 diabetes on changes in plasma amino acid concentrations in response to exogenous glucagon (15). This evidence concerns the gene GCG and obesity due to melanocortin 4 receptor deficiency.