There are several factors of arm distension and weakness as follows:1. Ionic disorder, in hypokalemia, arm distension and weakness, limb weakness and other situations occur.2. Patients with peripheral radiculitis, such as diabetes mellitus combined with patients with peripheral neuritis, will also have arm distension and weakness.3. Patients with diabetes mellitus combined with hypoglycemia will also have arm distension and weakness, palpitation, chest tightness, sweating and other situations.4, Infectious conditions, such as localized bacterial, viral, fungal and other infections of the arm, local cellulitis, or localized dengue, will also appear swelling and weakness.