Diabetes mellitus, or simply diabetes, is a group of diseases in which a person does not produce enough insulin, or because it does not respond to the insulin that is produced. Insulin is a hormone that controls the amount of glucose (sugar) in the blood. Diabetes leads to high blood sugar levels, which can lead to damage of blood vessels, organs, and nerves.
If genetics has taught us anything about diabetes, it's that, for most people, genes aren't the whole story. True, a few rare kinds of diabetes—including those collectively called MODY for maturity-onset diabetes of the young—have been traced to defects in a single gene. But for other types of diabetes, hereditary factors are still not well understood.
A chronic metabolic disorder in which the use of carbohydrate is impaired and that of lipid and protein is enhanced. It is caused by an absolute or relative deficiency of insulin and is characterized, in more severe cases, by chronic hyperglycemia, glycosuria, water and electrolyte loss, ketoacidosis, and coma. Long-term complications include neuropathy, retinopathy, nephropathy, generalized degenerative changes in large and small blood vessels, and increased susceptibility to infection.
Rosiglitazone, a thiazolidinedione, has not been found to improve long-term outcomes even though it improves blood sugar levels. Additionally it is associated with increased rates of heart disease and death. Angiotensin-converting enzyme inhibitors (ACEIs) prevent kidney disease and improve outcomes in those with diabetes. The similar medications angiotensin receptor blockers (ARBs) do not. A 2016 review recommended treating to a systolic blood pressure of 140 to 150 mmHg.
The good news is that if you have diabetes, you have a great amount of control in managing your disease. Although it can be difficult to manage a disease on a daily basis, the resources and support for people with diabetes is endless. It's important for you to receive as much education as possible so that you can take advantage of all the good information that is out there (and weed out the bad).
Autonomic changes involving cardiovascular control (eg, heart rate, postural responses) have been described in as many as 40% of children with diabetes. Cardiovascular control changes become more likely with increasing duration and worsening control.  In a study by 253 patients with type 1 diabetes (mean age at baseline 14.4 y), Cho et al reported that the prevalence of cardiac autonomic dysfunction increases in association with higher body mass index and central adiposity. 
In type 1 diabetes (formerly called insulin-dependent diabetes or juvenile-onset diabetes), the body's immune system attacks the insulin-producing cells of the pancreas, and more than 90% of them are permanently destroyed. The pancreas, therefore, produces little or no insulin. Only about 5 to 10% of all people with diabetes have type 1 disease. Most people who have type 1 diabetes develop the disease before age 30, although it can develop later in life.
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.
Can diabetes be prevented? Why are so many people suffering from it now over decades past? While there will never be anyway to possibly avoid genetic diabetes, there have been cases where dietary changes could perhaps have been made to delay or prevent the ailment from further developing. Doctors report that obesity plays a role, as well as activity levels, and even overall mental health often can be common threads of pre-diabetic patients.
If, on the other hand, you are already starting to develop complications or your medication regimen has changed because your blood sugars are getting higher, remember that diabetes is a progressive disease—and sometimes these things just happen without any influence from your own actions. As you age, beta cells in the pancreas get tired and stop working. If you've had diabetes for 20 years and now need to start insulin, for example, it doesn't mean you've failed. It just means that your body needs some help. Make sure you continue to receive education and that you continue to have someone to lean on when you need it, and keep the lines of communication open with your doctor. It truly can make a difference.
Type 2 diabetes is a preventable disease that affects more than 9 percent of the U.S. population, or about 29 million people. According to the Centers for Disease Control and Prevention, more than a quarter — some 8 million people — remain undiagnosed. With complications including nerve damage, kidney damage, poor blood circulation, and even death, it’s important for us all to know the early signs of type 2 diabetes.