Blood glucose ranges are usually between 60 and 120 in a person with a normal metabolism. If a person has a metabolic dysfunction such as diabetes where the body either does not produce sufficient quantities of insulin or is resistant to the insulin produced the blood glucose ranges can swing wildly and at times can become so out of control as to be debilitating, sometimes even leading to coma or death. Prolonged, but less severe abnormal blood glucose ranges can damage the kidneys, liver, and even the heart, and can be a contributing factor to the development of glaucoma.