TFG and type 1 diabetes mellitus: Clinically, a high incidence of glucose intolerance (7 with non-insulin-dependent diabetes mellitus (NIDDM) and 4 with impaired glucose tolerance (IGT) among 16 patients) was reported in patients with HMSN-P13, and two heterozygous missense mutations of TFG have been identified to date as being causative6–8.