Genetic variations likely act together with health and lifestyle factors to influence an individual's overall risk of type 2 diabetes. All of these factors are related, directly or indirectly, to the body's ability to produce and respond to insulin. Health conditions that predispose to the disease include overweight or obesity, insulin resistance, prediabetes (higher-than-normal blood sugar levels that do not reach the cutoff for diabetes), and a form of diabetes called gestational diabetes that occurs during pregnancy. Lifestyle factors including smoking, a poor diet, and physical inactivity also increase the risk of type 2 diabetes.
Although a defect in mitochondrial function is associated with extremes of insulin resistance in skeletal muscle (30), this does not appear to be relevant to the etiology of type 2 diabetes. No defect is present in early type 2 diabetes but rather is directly related to ambient plasma glucose concentration (31). Observed rates of mitochondrial ATP production can be modified by increasing or decreasing plasma fatty acid concentration (32,33). Additionally, the onset of insulin stimulation of mitochondrial ATP synthesis is slow, gradually increasing over 2 h, and quite distinct from the acute onset of insulin’s metabolic effects (34). Although it remains possible that secondary mitochondrial effects of hyperglycemia and excess fatty acids exist, there is no evidence for a primary mitochondrial defect underlying type 2 diabetes.
In fact, high blood pressure is very common with diabetes, as two in three adults with diabetes also have high blood pressure, according to the American Diabetes Association (ADA). High blood pressure doesn't always have noticeable symptoms and you may not know you have it unless your doctor checks. Still, it can lead to serious complications including heart attack, stroke, eye problems, and kidney disease.
Fortunately, if sleep deprivation lasts only a few days, these effects can be reversed—and insulin levels can improve—with as little as two full nights of sleep (nearly 10 hours per night). This is comforting to know when you’re in a pinch and need to stay up late for several consecutive nights to meet a deadline or deal with a family emergency. But don’t make this a habit. In the long run, it’s best to try to get seven to nine hours of uninterrupted sleep on a nightly basis so you can feel and function optimally and reduce your risk of developing type 2 diabetes and other health problems.
Some people with type 2 diabetes are treated with insulin. Insulin is either injected with a syringe several times per day, or delivered via an insulin pump. The goal of insulin therapy is to mimic the way the pancreas would produce and distribute its own insulin, if it were able to manufacture it. Taking insulin does not mean you have done a bad job of trying to control your blood glucose—instead it simply means that your body doesn’t produce or use enough of it on its own to cover the foods you eat.
There are a number of rare cases of diabetes that arise due to an abnormality in a single gene (known as monogenic forms of diabetes or "other specific types of diabetes").[10][13] These include maturity onset diabetes of the young (MODY), Donohue syndrome, and Rabson–Mendenhall syndrome, among others.[10] Maturity onset diabetes of the young constitute 1–5% of all cases of diabetes in young people.[39]

One of the key factors in Joslin’s treatment of diabetes is tight blood glucose control, so be certain that your treatment helps get your blood glucose readings as close to normal as safely possible. Patients should discuss with their doctors what their target blood glucose range is. It is also important to determine what your goal is for A1C readings (a test that determines how well your diabetes is controlled over the past 2-3 months). By maintaining blood glucose in the desired range, you’ll likely avoid many of the complications some people with diabetes face.

Heart disease and stroke. People who have diabetes are at greater risk for heart disease and stroke. The risk is even greater for people who have diabetes and smoke, have high blood pressure, have a family history of heart disease, or are overweight. Heart disease is easiest to treat when it is caught early. It is very important to see your doctor on a regular basis. He or she can test for early signs of heart disease. This includes checking cholesterol levels. If your cholesterol is higher than the recommended level, your doctor will talk to you about lifestyle changes and medicine to help get your cholesterol under control.

Diabetic hyperglycemic hyperosmolar syndrome (HHS) occurs in type 2 diabetes. It involves very high blood glucose levels but no ketones. You might become dehydrated with this condition. You may even lose consciousness. HHS is most common in people whose diabetes is undiagnosed or who haven’t been able to control their diabetes. It can also be caused by a heart attack, stroke, or infection.
Type 2 diabetes is typically a chronic disease associated with a ten-year-shorter life expectancy.[10] This is partly due to a number of complications with which it is associated, including: two to four times the risk of cardiovascular disease, including ischemic heart disease and stroke; a 20-fold increase in lower limb amputations, and increased rates of hospitalizations.[10] In the developed world, and increasingly elsewhere, type 2 diabetes is the largest cause of nontraumatic blindness and kidney failure.[24] It has also been associated with an increased risk of cognitive dysfunction and dementia through disease processes such as Alzheimer's disease and vascular dementia.[25] Other complications include acanthosis nigricans, sexual dysfunction, and frequent infections.[23]
Creatinine is a chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatine, a molecule of major importance for energy production in muscles. Creatinine has been found to be a fairly reliable indicator of kidney function. As the kidneys become impaired the creatinine level in the blood will rise. Normal levels of creatinine in the blood vary from gender and age of the individual.
Type 2 diabetes was also previously referred to as non-insulin dependent diabetes mellitus (NIDDM), or adult-onset diabetes mellitus (AODM). In type 2 diabetes, patients can still produce insulin, but do so relatively inadequately for their body's needs, particularly in the face of insulin resistance as discussed above. In many cases this actually means the pancreas produces larger than normal quantities of insulin. A major feature of type 2 diabetes is a lack of sensitivity to insulin by the cells of the body (particularly fat and muscle cells).
"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.[38] 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).[38] These phenomena are believed to occur no more frequently than in 1% to 2% of persons with type 1 diabetes.[39]

Diabetes mellitus is a chronic disease, for which there is no known cure except in very specific situations.[75] Management concentrates on keeping blood sugar levels as close to normal, without causing low blood sugar. This can usually be accomplished with a healthy diet, exercise, weight loss, and use of appropriate medications (insulin in the case of type 1 diabetes; oral medications, as well as possibly insulin, in type 2 diabetes).
The twin cycle hypothesis of the etiology of type 2 diabetes. During long-term intake of more calories than are expended each day, any excess carbohydrate must undergo de novo lipogenesis, which particularly promotes fat accumulation in the liver. Because insulin stimulates de novo lipogenesis, individuals with a degree of insulin resistance (determined by family or lifestyle factors) will accumulate liver fat more readily than others because of higher plasma insulin levels. In turn, the increased liver fat will cause relative resistance to insulin suppression of hepatic glucose production. Over many years, a modest increase in fasting plasma glucose level will stimulate increased basal insulin secretion rates to maintain euglycemia. The consequent hyperinsulinemia will further increase the conversion of excess calories to liver fat. A cycle of hyperinsulinemia and blunted suppression of hepatic glucose production becomes established. Fatty liver leads to increased export of VLDL triacylglycerol (85), which will increase fat delivery to all tissues, including the islets. This process is further stimulated by elevated plasma glucose levels (85). Excess fatty acid availability in the pancreatic islet would be expected to impair the acute insulin secretion in response to ingested food, and at a certain level of fatty acid exposure, postprandial hyperglycemia will supervene. The hyperglycemia will further increase insulin secretion rates, with consequent enhancement of hepatic lipogenesis, spinning the liver cycle faster and driving the pancreas cycle. Eventually, the fatty acid and glucose inhibitory effects on the islets reach a trigger level that leads to a relatively sudden onset of clinical diabetes. Figure adapted with permission from Taylor (98).

Hemoglobin A1c or HbA1c is a protein on the surface of red blood cells. The HbA1c test is used to monitor blood sugar levels in people with type 1 and type 2 diabetes over time. Normal HbA1c levels are 6% or less. HbA1c levels can be affected by insulin use, fasting, glucose intake (oral or IV), or a combination of these and other factors. High hemoglobin A1c levels in the blood increases the risk of microvascular complications, for example, diabetic neuropathy, eye, and kidney disease.


When you hear the word “diabetes,” your first thought is likely about high blood sugar. Blood sugar is an often-underestimated component of your health. When it’s out of whack over a long period of time, it could develop into diabetes. Diabetes affects your body’s ability to produce or use insulin, a hormone that allows your body to turn glucose (sugar) into energy. Here’s what symptoms may occur to your body when diabetes takes effect.
Most cases of diabetes involve many genes, with each being a small contributor to an increased probability of becoming a type 2 diabetic.[10] If one identical twin has diabetes, the chance of the other developing diabetes within his lifetime is greater than 90%, while the rate for nonidentical siblings is 25–50%.[13] As of 2011, more than 36 genes had been found that contribute to the risk of type 2 diabetes.[38] All of these genes together still only account for 10% of the total heritable component of the disease.[38] The TCF7L2 allele, for example, increases the risk of developing diabetes by 1.5 times and is the greatest risk of the common genetic variants.[13] Most of the genes linked to diabetes are involved in beta cell functions.[13]
Evidence linking hepatic insulin sensitivity to intraorgan triglyceride content has been steadily accumulating. In insulin-treated type 2 diabetes, insulin dose correlates with the extent of fatty liver (35), and in turn, this is associated with insulin sensitivity to suppression of hepatic glucose production (36). Decreasing the fat content of liver is associated with improvement in insulin suppression of glucose production and, thereby, with improvement in fasting plasma glucose (20,23).
You’ll find just about everything you might want to track in this app: blood glucose, insulin, medication, meals, water intake, and physical activity. It comes with a built-in bar-code scanner and a food database to tally up your nutrient intake. Also included is a GPS tracker to log distances for walking, running, or bicycling. It will remind you to check your blood sugar, and it will give you summary reports to help you understand the relationships between blood sugar, diet, and exercise. Add the app’s subscription for a few premium features, including syncing with fitness trackers. (The current subscription cost is $8.99 per month or $59.99 per year.)
Culturally appropriate education may help people with type 2 diabetes control their blood sugar levels, for up to 24 months.[91] If changes in lifestyle in those with mild diabetes has not resulted in improved blood sugars within six weeks, medications should then be considered.[23] There is not enough evidence to determine if lifestyle interventions affect mortality in those who already have DM2.[63]
This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.
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