We report a Japanese family with distal hereditary motor neuronopathy type II (distal HMN II) due to a novel K141Q mutation in heat-shock 27-kDa protein 1 gene (HSPB1/HSP27). A 47-year-old man (proband) with diabetes mellitus (DM) developed distal wasting and weakness of the legs and severe autonomic dysfunctions in his early forties, while his father and grandfather, without DM, demonstrated slowly progressive muscular wasting and weakness in all limbs still later in life. This mutation appears linked with the late-onset clinical phenotype as distal HMN II. Severe autonomic disturbances in the proband were probably due to uncontrolled DM, but may have been related to HSPB1 mutation.