Type 2 diabetes is typically a chronic disease associated with a ten-year-shorter life expectancy. 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. In the developed world, and increasingly elsewhere, type 2 diabetes is the largest cause of nontraumatic blindness and kidney failure. 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. Other complications include acanthosis nigricans, sexual dysfunction, and frequent infections.
Nerve damage from diabetes is called diabetic neuropathy and is also caused by disease of small blood vessels. In essence, the blood flow to the nerves is limited, leaving the nerves without blood flow, and they get damaged or die as a result (a term known as ischemia). Symptoms of diabetic nerve damage include numbness, burning, and aching of the feet and lower extremities. When the nerve disease causes a complete loss of sensation in the feet, patients may not be aware of injuries to the feet, and fail to properly protect them. Shoes or other protection should be worn as much as possible. Seemingly minor skin injuries should be attended to promptly to avoid serious infections. Because of poor blood circulation, diabetic foot injuries may not heal. Sometimes, minor foot injuries can lead to serious infection, ulcers, and even gangrene, necessitating surgical amputation of toes, feet, and other infected parts.
Most pediatric patients with diabetes have type 1 diabetes mellitus (T1DM) and a lifetime dependence on exogenous insulin. Diabetes mellitus (DM) is a chronic metabolic disorder caused by an absolute or relative deficiency of insulin, an anabolic hormone. Insulin is produced by the beta cells of the islets of Langerhans located in the pancreas, and the absence, destruction, or other loss of these cells results in type 1 diabetes (insulin-dependent diabetes mellitus [IDDM]). A possible mechanism for the development of type 1 diabetes is shown in the image below. (See Etiology.)
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).
Can type 2 diabetes be prevented? It is possible to reduce the risk of developing type 2 diabetes, although the underlying risk of type 2 diabetes depends strongly on genetic factors. But there was less type 2 diabetes around some years ago when people had a more active life and didn’t eat a modern Western diet. So it is fair to say that risk of getting type 2 diabetes is based on a genetic predisposition that is aggravated by lifestyle. Type 2 diabetes is associated with obesity, as well as a variety of environmental factors. To lower the risk of developing type 2 diabetes (as well as other diseases), it is highly recommended to exercise often, eat healthily, and maintain a healthy weight.
Your body is like a car—it needs fuel to function. Its primary source of fuel is glucose (sugar), which is gained from foods that contain carbohydrates that get broken down. Insulin, a hormone produced by the pancreas, takes sugar from your blood to your cells to use for energy. However, when you have diabetes, either your pancreas isn't making enough insulin or the insulin that your body is making isn't being used the way it's supposed to be, typically because the cells become resistant to it.
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.
These diabetes complications are related to blood vessel diseases and are generally classified into small vessel disease, such as those involving the eyes, kidneys and nerves (microvascular disease), and large vessel disease involving the heart and blood vessels (macrovascular disease). Diabetes accelerates hardening of the arteries (atherosclerosis) of the larger blood vessels, leading to coronary heart disease (angina or heart attack), strokes, and pain in the lower extremities because of lack of blood supply (claudication).
Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can result in minor injuries, blisters, or callouses becoming infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The most serious consequence of this condition is the need for amputation of toes, feet, or legs due to severe infection.
Some people who have type 2 diabetes can achieve their target blood sugar levels with diet and exercise alone, but many also need diabetes medications or insulin therapy. The decision about which medications are best depends on many factors, including your blood sugar level and any other health problems you have. Your doctor might even combine drugs from different classes to help you control your blood sugar in several different ways.
Cataracts and glaucoma are also more common among diabetics. It is also important to note that since the lens of the eye lets water through, if blood sugar concentrations vary a lot, the lens of the eye will shrink and swell with fluid accordingly. As a result, blurry vision is very common in poorly controlled diabetes. Patients are usually discouraged from getting a new eyeglass prescription until their blood sugar is controlled. This allows for a more accurate assessment of what kind of glasses prescription is required.
A final note about type 1: Some people have a "honeymoon" period, a brief remission of symptoms while the pancreas is still secreting some insulin. The honeymoon phase typically occurs after insulin treatment has been started. A honeymoon can last as little as a week or even up to a year. But the absence of symptoms doesn't mean the diabetes is gone. The pancreas will eventually be unable to secrete insulin, and, if untreated, the symptoms will return.
The body obtains glucose from three main sources: the intestinal absorption of food; the breakdown of glycogen (glycogenolysis), the storage form of glucose found in the liver; and gluconeogenesis, the generation of glucose from non-carbohydrate substrates in the body. Insulin plays a critical role in balancing glucose levels in the body. Insulin can inhibit the breakdown of glycogen or the process of gluconeogenesis, it can stimulate the transport of glucose into fat and muscle cells, and it can stimulate the storage of glucose in the form of glycogen.
Injections of insulin may either be added to oral medication or used alone. Most people do not initially need insulin. When it is used, a long-acting formulation is typically added at night, with oral medications being continued. Doses are then increased to effect (blood sugar levels being well controlled). When nightly insulin is insufficient, twice daily insulin may achieve better control. The long acting insulins glargine and detemir are equally safe and effective, and do not appear much better than neutral protamine Hagedorn (NPH) insulin, but as they are significantly more expensive, they are not cost effective as of 2010. In those who are pregnant insulin is generally the treatment of choice.
Over recent decades, and particularly in the past five years, researchers have found dozens of genes with links to diabetes. The count stands at about 50 genes for type 1 and 38 for type 2. The numbers have risen quickly in recent years because of advances in the gene-sequencing technology used to conduct genome-wide association studies. This technique involves taking the genetic compositions of a group of people with a disease and comparing them en masse to the genomes of people who don't have the disease.
Type 1 diabetes occurs when the immune system attacks and destroys the insulin-producing cells in the pancreas (the beta cells). As a result, the body is left without enough insulin to function normally (i.e. it becomes insulin deficient). This is called an autoimmune reaction, because the body attacks itself and produces antibodies to its own insulin-producing cells, thereby destroying them.
Insulin is vital to patients with type 1 diabetes - they cannot live without a source of exogenous insulin. Without insulin, patients with type 1 diabetes develop severely elevated blood sugar levels. This leads to increased urine glucose, which in turn leads to excessive loss of fluid and electrolytes in the urine. Lack of insulin also causes the inability to store fat and protein along with breakdown of existing fat and protein stores. This dysregulation, results in the process of ketosis and the release of ketones into the blood. Ketones turn the blood acidic, a condition called diabetic ketoacidosis (DKA). Symptoms of diabetic ketoacidosis include nausea, vomiting, and abdominal pain. Without prompt medical treatment, patients with diabetic ketoacidosis can rapidly go into shock, coma, and even death may result.
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.
Of course, you’re exhausted every now and then. But ongoing fatigue is an important symptom to pay attention to; it might mean the food you’re eating for energy isn’t being broken down and used by cells as it’s supposed to. “You’re not getting the fuel your body needs,” says Dobbins. “You’re going to be tired and feel sluggish.” But in many cases of type 2 diabetes, your sugar levels can be elevated for awhile, so these diabetes symptoms could come on slowly.
A 2009 study shows how genetic information may shed light on the environment-gene interactions that lead to type 1. In the study, researchers found that one of the type 1 genes mediates the immune system's response to viruses. This finding supported the longtime hypothesis that a virus may somehow make the immune system attack the insulin-producing cells in the pancreas in people who are genetically susceptible to developing diabetes.
Type 2 diabetes is usually associated with being overweight (BMI greater than 25), and is harder to control when food choices are not adjusted, and you get no physical activity. And while it’s true that too much body fat and physical inactivity (being sedentary) does increase the likelihood of developing type 2, even people who are fit and trim can develop this type of diabetes.2,3
The term brittle diabetes has been used to refer to people who have dramatic recurrent swings in blood glucose levels, often for no apparent reason. However, this term is no longer used. People with type 1 diabetes may have more frequent swings in blood glucose levels because insulin production is completely absent. Infection, delayed movement of food through the stomach, and other hormonal disorders may also contribute to blood glucose swings. In all people who have difficulty controlling blood glucose, doctors look for other disorders that might be causing the problem and also give people additional education on how to monitor diabetes and take their drugs.
Patients with type 1 diabetes require life-long treatment with exogenous (artificial) insulin to regulate their blood sugar levels. This insulin may be given through the use of a hypodermic needle (seen right), or other methods such as the use of an insulin pump. Over time, many patients suffer chronic complications: vascular, neurological and organ-specific (such as kidney and eye disease). The frequency and severity of these complications is related to duration that the patient has suffered the disease for, and by how well their blood sugar levels have been controlled. If blood sugar levels, blood pressure and lipids are tightly controlled, many complications of diabetes may be prevented. Some patients may develop the major emergency complication of diabetes, known as ketoacidosis (extremely high blood glucose levels accompanied with extremely low insulin levels), which has a mortality rate of 5-10%.
Assemble a Medical Team: Whether you've had diabetes for a long time or you've just been diagnosed, there are certain doctors that are important to see. It is extremely important to have a good primary care physician. This type of doctor will help coordinate appointments for other physicians if they think that you need it. Some primary physicians treat diabetes themselves, whereas others will recommend that you visit an endocrinologist for diabetes treatment. An endocrinologist is a person who specializes in diseases of the endocrine system, diabetes being one of them.
According to the Mayo Clinic, doctors may use other tests to diagnose diabetes. For example, they may conduct a fasting blood glucose test, which is a blood glucose test done after a night of fasting. While a fasting blood sugar level of less than 100 milligrams per deciliter (mg/dL) is normal, one that is between 100 to 125 mg/dL signals prediabetes, and a reading that reaches 126 mg/dL on two separate occasions means you have diabetes.