Pain and a stretching sensation in the arm muscles can occur for several reasons in a person with diabetes. Your fasting sugar of 120 mg/dL is reasonably controlled, but diabetes can still sometimes cause muscle pain, nerve irritation, or reduced blood circulation. Mildly raised blood pressure at 142/92 mmHg is unlikely to directly cause arm muscle pain, but it should be monitored regularly. Your medicines may also play a role. Pioglitazone in Gemer P2 may occasionally cause muscle discomfort or fluid retention. Huminsulin 30/70 (Human insulin) may rarely cause low potassium levels, which can lead to muscle cramps or weakness. Vitamin supplements, such as Evion LC, are usually not harmful, but interactions and individual reactions can vary. You should also consider simple causes such as muscle strain, poor posture, dehydration, or a vitamin deficiency. However, if the pain increases, weakness develops, swelling appears, or you have chest discomfort or breathlessness, consult your doctor immediately. Your doctor may advise blood tests for electrolytes, vitamin levels, kidney function, and muscle enzymes if symptoms continue.