Abstract: Low-level laser therapy is applied externally through the skin of the patient to targeted areas of a of a patient's body to treat diabetes or prediabetes. A patient is first diagnosed with diabetes or prediabetes, preferably by blood draws that measure insulin, A1C, or glucose levels. A therapeutic amount of laser energy to apply is determined from a patient's biological factors such as body mass index. The therapeutic amount of laser energy is applied one or more times over a two week time period. The patient is then retested for diabetes or prediabetes. If necessary, a new therapeutic amount of laser energy is determined according to any changes in the patient's diabetes or prediabetes diagnosis and any changes in the patient's biological factors. Adjusted treatments with low-level laser energy continue until the diabetes or prediabetes diagnosis is removed.