Insulin is a hormone produced by the beta cells within the pancreas in response to the intake of food. The role of insulin is to lower blood sugar (glucose) levels by allowing cells in the muscle, liver and fat to take up sugar from the bloodstream that has been absorbed from food, and store it away as energy. In type 1 diabetes (previously called insulin-dependent diabetes mellitus), the insulin-producing cells are destroyed and the body is not able to produce insulin naturally. This means that sugar is not stored away but is constantly released from energy stores giving rise to high sugar levels in the blood. This in turn causes dehydration and thirst (because the high glucose ‘spills over’ into the urine and pulls water out of the body at the same time). To exacerbate the problem, because the body is not making insulin it ‘thinks’ that it is starving so does everything it can to release even more stores of energy into the bloodstream. So, if left untreated, patients become increasingly unwell, lose weight, and develop a condition called diabetic ketoacidosis, which is due to the excessive release of acidic energy stores and causes severe changes to how energy is used and stored in the body.
It is recommended that all people with type 2 diabetes get regular eye examination.[13] There is weak evidence suggesting that treating gum disease by scaling and root planing may result in a small short-term improvement in blood sugar levels for people with diabetes.[79] There is no evidence to suggest that this improvement in blood sugar levels is maintained longer than 4 months.[79] There is also not enough evidence to determine if medications to treat gum disease are effective at lowering blood sugar levels.[79]
This depends on the type of diabetes. Type 2 diabetes, and to a lesser extent type 1 diabetes, may run in families. If a parent has diabetes, their children will not necessarily get it but they are at an increased risk. In type 2 diabetes, lifestyle factors such as being overweight (obesity) and lack of exercise can significantly increase your risk of developing diabetes. Some rarer types of diabetes mellitus may be inherited.

Fasting glucose test This test involves giving a blood sample after you have fasted for eight hours. (18) If you have a fasting blood sugar level of less than 100 milligrams per deciliter (mg/dl), your blood sugar levels are normal. But if you have one from 100 to 125 mg/dl, you have prediabetes, and if you have 126 mg/dl on two separate occasions, you have diabetes. (17)

Type 2 diabetes is the most common type of diabetes. It is a chronic problem in which blood glucose (sugar) can no longer be regulated. There are two reasons for this. First, the cells of the body become resistant to insulin (insulin resistant). Insulin works like a key to let glucose (blood sugar) move out of the blood and into the cells where it is used as fuel for energy. When the cells become insulin resistant, it requires more and more insulin to move sugar into the cells, and too much sugar stays in the blood. Over time, if the cells require more and more insulin, the pancreas can't make enough insulin to keep up and begins to fail.
Diagnosis. The most common diagnostic tests for diabetes are chemical analyses of the blood such as the fasting plasma glucose. Capillary blood glucose monitoring can be used for screening large segments of the population. Portable equipment is available and only one drop of blood from the fingertip or earlobe is necessary. Capillary blood glucose levels have largely replaced analysis of the urine for glucose. Testing for urinary glucose can be problematic as the patient may have a high renal threshold, which would lead to a negative reading for urinary glucose when in fact the blood glucose level was high.

"Brittle" diabetes, also known as unstable diabetes or labile diabetes, is a term that was traditionally used to describe the dramatic and recurrent swings in glucose levels, often occurring for no apparent reason in insulin-dependent diabetes. This term, however, has no biologic basis and should not be used.[39] Still, type 1 diabetes can be accompanied by irregular and unpredictable high blood sugar levels, frequently with ketosis, and sometimes with serious low blood sugar levels. Other complications include an impaired counterregulatory response to low blood sugar, infection, gastroparesis (which leads to erratic absorption of dietary carbohydrates), and endocrinopathies (e.g., Addison's disease).[39] These phenomena are believed to occur no more frequently than in 1% to 2% of persons with type 1 diabetes.[40]
FASTING GLUCOSE TEST. Blood is drawn from a vein in the patient's arm after a period at least eight hours when the patient has not eaten, usually in the morning before breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results.

Not all people with diabetes need drug therapy. A healthy eating plan and exercise alone can be enough if the person makes significant lifestyle changes. Other signs, symptoms, and complications also may need treatment. For example, nutritional deficiencies should be corrected, heart or kidney disease may need to be treated, and vision must be checked for eye problems like diabetic retinopathy.
There is no single gene that “causes” type 1 diabetes. Instead, there are a large number of inherited factors that may increase an individual’s likelihood of developing diabetes. This is known as multifactorial inheritance. The genes implicated in the development of type 1 diabetes mellitus control the human leukocyte antigen (HLA) system. This system is involved in the complex process of identifying cells which are a normal part of the body, and distinguishing them from foreign cells, such as those of bacteria or viruses. In an autoimmune disease such as diabetes mellitus, this system makes a mistake in identifying the normal ‘self’ cells as ‘foreign’, and attacks the body.  

Commonly, diabetic patients’ random blood glucose measurement will be greater than 200 mg/dL. Additionally, diabetic patients’ urinalysis will be positive for greater than 30 mg/g of microalbumin on at least two of three consecutive sampling dates. Type 2 diabetics who have had diabetes mellitus for more than 2 years will usually have a fasting C-peptide level greater than 1.0 ng/dL. Patients with type 1 diabetes will have islet cell and anti-insulin autoantibodies present in their blood within 6 months of diagnosis. These antibodies, though, usually fade after 6 months.

Kidney damage from diabetes is called diabetic nephropathy. The onset of kidney disease and its progression is extremely variable. Initially, diseased small blood vessels in the kidneys cause the leakage of protein in the urine. Later on, the kidneys lose their ability to cleanse and filter blood. The accumulation of toxic waste products in the blood leads to the need for dialysis. Dialysis involves using a machine that serves the function of the kidney by filtering and cleaning the blood. In patients who do not want to undergo chronic dialysis, kidney transplantation can be considered.
Exercise. A program of regular exercise gives anyone a sense of good health and well-being; for persons with diabetes it gives added benefits by helping to control blood glucose levels, promoting circulation to peripheral tissues, and strengthening the heart beat. In addition, there is evidence that exercise increases the number of insulin receptor sites on the surface of cells and thus facilitates the metabolism of glucose. Many specialists in diabetes consider exercise so important in the management of diabetes that they prescribe rather than suggest exercise.
Because type 2 diabetes is linked to high levels of sugar in the blood, it may seem logical to assume that eating too much sugar is the cause of the disease. But of course, it’s not that simple. “This has been around for years, this idea that eating too much sugar causes diabetes — but the truth is, type 2 diabetes is a multifactorial disease with many different types of causes,” says Lynn Grieger, RDN, CDE, a nutrition coach in Prescott, Arizona, and a medical reviewer for Everyday Health. “Type 2 diabetes is really complex.”
In addition to the problems with an increase in insulin resistance, the release of insulin by the pancreas may also be defective and suboptimal. In fact, there is a known steady decline in beta cell production of insulin in type 2 diabetes that contributes to worsening glucose control. (This is a major factor for many patients with type 2 diabetes who ultimately require insulin therapy.) Finally, the liver in these patients continues to produce glucose through a process called gluconeogenesis despite elevated glucose levels. The control of gluconeogenesis becomes compromised.
A second theory, dubbed the hygiene hypothesis, blames the rise of type 1 on a society that's too clean. Good housekeeping and hygiene habits mean far fewer interactions with germs, which in turn may foster an immune system prone to going awry. "In a developing country, you have more infectious disease. This is associated with a lower risk of type 1 diabetes," says Li Wen, MD, PhD, an immunologist at the Yale University School of Medicine. In her lab, rodents raised in hyper-clean environments are more likely to get type 1 than those reared in dirtier cages.
Environmental factors are important, because even identical twins have only a 30-60% concordance for type 1 diabetes mellitus and because incidence rates vary in genetically similar populations under different living conditions. [25] No single factor has been identified, but infections and diet are considered the 2 most likely environmental candidates.
Medications used to treat diabetes do so by lowering blood sugar levels. There is broad consensus that when people with diabetes maintain tight glucose control (also called "tight glycemic control") -- keeping the glucose levels in their blood within normal ranges - that they experience fewer complications like kidney problems and eye problems.[84][85] There is however debate as to whether this is cost effective for people later in life.[86]
Classic symptoms of DM are polyuria, polydipsia, and weight loss. In addition, patients with hyperglycemia often have blurred vision, increased food consumption (polyphagia), and generalized weakness. When a patient with type 1 DM loses metabolic control (such as during infections or periods of noncompliance with therapy), symptoms of diabetic ketoacidosis occur. These may include nausea, vomiting, dizziness on arising, intoxication, delirium, coma, or death. Chronic complications of hyperglycemia include retinopathy and blindness, peripheral and autonomic neuropathies, glomerulosclerosis of the kidneys (with proteinuria, nephrotic syndrome, or end-stage renal failure), coronary and peripheral vascular disease, and reduced resistance to infections. Patients with DM often also sustain infected ulcerations of the feet, which may result in osteomyelitis and the need for amputation.
Intensive blood sugar lowering (HbA1c<6%) as opposed to standard blood sugar lowering (HbA1c of 7–7.9%) does not appear to change mortality.[74][75] The goal of treatment is typically an HbA1c of 7 to 8% or a fasting glucose of less than 7.2 mmol/L (130 mg/dl); however these goals may be changed after professional clinical consultation, taking into account particular risks of hypoglycemia and life expectancy.[59][76][77] Despite guidelines recommending that intensive blood sugar control be based on balancing immediate harms with long-term benefits, many people – for example people with a life expectancy of less than nine years who will not benefit, are over-treated.[78]
Kidney disease: According to the Centers for Disease Control and Prevention (CDC), an estimated 33 percent of people with diabetes have chronic kidney disease. Diabetes can also damage blood vessels in the kidneys, impairing function. The kidneys play a vital role in balancing fluid levels and removing waste from the body. Kidney health is therefore vital for preserving overall health.

Kidney disease: According to the Centers for Disease Control and Prevention (CDC), an estimated 33 percent of people with diabetes have chronic kidney disease. Diabetes can also damage blood vessels in the kidneys, impairing function. The kidneys play a vital role in balancing fluid levels and removing waste from the body. Kidney health is therefore vital for preserving overall health.
John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.