Per the WHO, people with fasting glucose levels from 6.1 to 6.9 mmol/l (110 to 125 mg/dl) are considered to have impaired fasting glucose.[70] people with plasma glucose at or above 7.8 mmol/l (140 mg/dl), but not over 11.1 mmol/l (200 mg/dl), two hours after a 75 gram oral glucose load are considered to have impaired glucose tolerance. Of these two prediabetic states, the latter in particular is a major risk factor for progression to full-blown diabetes mellitus, as well as cardiovascular disease.[71] The American Diabetes Association (ADA) since 2003 uses a slightly different range for impaired fasting glucose of 5.6 to 6.9 mmol/l (100 to 125 mg/dl).[72]
Type 2 diabetes is characterized by insulin resistance, which may be combined with relatively reduced insulin secretion.[11] The defective responsiveness of body tissues to insulin is believed to involve the insulin receptor. However, the specific defects are not known. Diabetes mellitus cases due to a known defect are classified separately. Type 2 diabetes is the most common type of diabetes mellitus.[2] Many people with type 2 diabetes have evidence of "prediabetes" (impaired fasting glucose and/or impaired glucose tolerance) for many years before meeting the criteria for type 2 diabetes.[citation needed] Prediabetes and easy overt type 2 diabetes can be reversed by a variety of measures and medications that improve insulin sensitivity or reduce the liver's glucose production.[citation needed]
Clinical Manifestations. Diabetes mellitus can present a wide variety of symptoms, from none at all to profound ketosis and coma. If the disease manifests itself late in life, patients may not know they have it until it is discovered during a routine examination, or when the symptoms of chronic vascular disease, insidious renal failure, or impaired vision cause them to seek medical help.
Diet and moderate exercise are the first treatments implemented in diabetes. For many Type II diabetics, weight loss may be an important goal in helping them to control their diabetes. A well-balanced, nutritious diet provides approximately 50-60% of calories from carbohydrates, approximately 10-20% of calories from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on age, weight, and activity level. The calorie intake also needs to be distributed over the course of the entire day so surges of glucose entering the blood system are kept to a minimum.

During digestion, pancreatic beta cells release not only insulin, but in a much smaller amount, the hormone amylin, which helps mediate sharp rises in blood glucose levels following meals. Pramlintide (Symlin) is a new, synthetic form of amylin that may help improve blood glucose control for some type 1 and type 2 diabetic people who use insulin. Pramlintide has few side effects (nausea is the main one) but it adds another set of injections to a diabetic person's daily pharmaceutical routine, as it cannot be mixed in the same syringe with insulin.

Sulfonylureasmay increase the risk of death from cardiovascular disease. Prolonged exercise and alcohol intake increase the risk for hypoglycemia. Patients undergoing surgery or who have had recent trauma, stress, or infection may need to switch from a sulfonylurea to insulin to manage blood sugar levels. People with kidney or liver disease need to take precaution.

Neuropathy — This is another term for nerve damage. The most common type is peripheral neuropathy, which affects nerves in the feet and hands. The nerves to the legs are damaged first, causing pain and numbness in the feet. This can advance to cause symptoms in the legs and hands. Damage to the nerves that control digestion, sexual function, and urination can also occur.
At the end of the test, a health care provider will compare the patient's blood sodium, vasopressin levels, and urine concentration to determine whether the patient has diabetes insipidus. Sometimes, the health care provider may administer medications during the test to see if they increase a patient's urine concentration. In other cases, the health care provider may give the patient a concentrated sodium solution intravenously at the end of the test to increase the patient's blood sodium level and determine if he or she has diabetes insipidus.