Reconciling the data on β2-adrenergic receptor polymorphism to those on loss of β-adrenergic sensitivity in diabetic patients with hypoglycemia unawareness, we hypothesize that hypoglycemia unawareness is at least partly the result of desensitization of the β2-adrenergic receptor and that patients who are homozygous for arginine at codon 16 are particularly susceptible for this desensitization process, whereas patients who are homozygous for glycine at codon 16 are resistant for desensitization.