Diabetes is suspected based on symptoms. Urine tests and blood tests can be used to confirm a diagnose of diabetes based on the amount of glucose found. Urine can also detect ketones and protein in the urine that may help diagnose diabetes and assess how well the kidneys are functioning. These tests also can be used to monitor the disease once the patient is on a standardized diet, oral medications, or insulin.

The protocol for therapy is determined by the type of diabetes; patients with either type 1 or type 2 must pay attention to their diet and exercise regimens. Insulin therapy may be prescribed for patients with type 2 diabetes as well as any who are dependent on insulin. In most cases, the type 2 diabetes patient can be treated effectively by reducing caloric intake, maintaining target weight, and promoting physical exercise.

If you are symptomatic (e.g., increased thirst or urination, unexplained weight loss), your doctor may only use a single test to diagnose diabetes/prediabetes. If you don't have any symptoms, one high blood glucose test doesn't necessarily mean you have diabetes/prediabetes. Your doctor will repeat one of the blood tests again on another day (generally 1 week later) to confirm the diagnosis.

The diabetic patient should learn to recognize symptoms of low blood sugar (such as confusion, sweats, and palpitations) and high blood sugar (such as, polyuria and polydipsia). When either condition results in hospitalization, vital signs, weight, fluid intake, urine output, and caloric intake are accurately documented. Serum glucose and urine ketone levels are evaluated. Chronic management of DM is also based on periodic measurement of glycosylated hemoglobin levels (HbA1c). Elevated levels of HbA1c suggest poor long-term glucose control. The effects of diabetes on other body systems (such as cerebrovascular, coronary artery, and peripheral vascular) should be regularly assessed. Patients should be evaluated regularly for retinal disease and visual impairment and peripheral and autonomic nervous system abnormalities, e.g., loss of sensation in the feet. The patient is observed for signs and symptoms of diabetic neuropathy, e.g., numbness or pain in the hands and feet, decreased vibratory sense, footdrop, and neurogenic bladder. The urine is checked for microalbumin or overt protein losses, an early indication of nephropathy. The combination of peripheral neuropathy and peripheral arterial disease results in changes in the skin and microvasculature that lead to ulcer formation on the feet and lower legs with poor healing. Approx. 45,000 lower-extremity diabetic amputations are performed in the U.S. each year. Many amputees have a second amputation within five years. Most of these amputations are preventable with regular foot care and examinations. Diabetic patients and their providers should look for changes in sensation to touch and vibration, the integrity of pulses, capillary refill, and the skin. All injuries, cuts, and blisters should be treated promptly. The patient should avoid constricting hose, slippers, shoes, and bed linens or walking barefoot. The patient with ulcerated or insensitive feet is referred to a podiatrist for continuing foot care and is warned that decreased sensation can mask injuries.
Diabetes experts feel that these blood glucose monitoring devices give patients a significant amount of independence to manage their disease process; and they are a great tool for education as well. It is also important to remember that these devices can be used intermittently with fingerstick measurements. For example, a well-controlled patient with diabetes can rely on fingerstick glucose checks a few times a day and do well. If they become ill, if they decide to embark on a new exercise regimen, if they change their diet and so on, they can use the sensor to supplement their fingerstick regimen, providing more information on how they are responding to new lifestyle changes or stressors. This kind of system takes us one step closer to closing the loop, and to the development of an artificial pancreas that senses insulin requirements based on glucose levels and the body's needs and releases insulin accordingly - the ultimate goal.
High blood glucose sets up a domino effect of sorts within your body. High blood sugar leads to increased production of urine and the need to urinate more often. Frequent urination causes you to lose a lot of fluid and become dehydrated. Consequently, you develop a dry mouth and feel thirsty more often. If you notice that you are drinking more than usual, or that your mouth often feels dry and you feel thirsty more often, these could be signs of type 2 diabetes.
Diabetes is a condition in which the body cannot properly store and use fuel for energy. The body's main fuel is a form of sugar called glucose, which comes from food (after it has been broken down). Glucose enters the blood and is used by cells for energy. To use glucose, the body needs a hormone called insulin that's made by the pancreas. Insulin is important because it allows glucose to leave the blood and enter the body's cells.

Good metabolic control can delay the onset and progression of diabetic retinopathy. Loss of vision and blindness in persons with diabetes can be prevented by early detection and treatment of vision-threatening retinopathy: regular eye examinations and timely intervention with laser treatment, or through surgery in cases of advanced retinopathy. There is evidence that, even in developed countries, a large proportion of those in need is not receiving such care due to lack of public and professional awareness, as well as an absence of treatment facilities. In developing countries, in many of which diabetes is now common, such care is inaccessible to the majority of the population.

The brain depends on glucose as a fuel. As glucose levels drop below 65 mg/dL (3.2 mmol/L) counterregulatory hormones (eg, glucagon, cortisol, epinephrine) are released, and symptoms of hypoglycemia develop. These symptoms include sweatiness, shaking, confusion, behavioral changes, and, eventually, coma when blood glucose levels fall below 30-40 mg/dL.
Also striking are the differences in incidence between mainland Italy (8.4 cases per 100,000 population) and the Island of Sardinia (36.9 cases per 100,000 population). These variations strongly support the importance of environmental factors in the development of type 1 diabetes mellitus. Most countries report that incidence rates have at least doubled in the last 20 years. Incidence appears to increase with distance from the equator. [31]
People with full-blown type 2 diabetes are not able to use the hormone insulin properly, and have what’s called insulin resistance. Insulin is necessary for glucose, or sugar, to get from your blood into your cells to be used for energy. When there is not enough insulin — or when the hormone doesn’t function as it should — glucose accumulates in the blood instead of being used by the cells. This sugar accumulation may lead to the aforementioned complications.