Over time, a prolonged exposure to high blood sugar can damage the nerves throughout the body — a condition called diabetic neuropathy. Some people may not have any symptoms of the damage, while others may notice numbness, tingling, or pain in the extremities. “At the beginning, [diabetic neuropathy] usually starts in the feet and then it progresses upward,” says Dr. Ovalle. Although most common in people who have had type 2 diabetes for 25 years or more, it can occur in people who have prediabetes as well. In some studies, almost 50 percent of unexplained peripheral neuropathy [in the extremities], whether painful or otherwise, turns out to be caused by prediabetes or diabetes, says Dr. Einhorn.
About 40% of diabetes sufferers require oral agents for satisfactory blood glucose control, and some 40% need insulin injections. This hormone was isolated by Frederic Banting and Charles Best in 1921 in Canada. It revolutionized the treatment of diabetes and prevention of its complications, transforming Type 1 diabetes from a fatal disease to one in which long-term survival became achievable.

Diabetes mellitus (“diabetes”) and hypertension, which commonly coexist, are global public health issues contributing to an enormous burden of cardiovascular disease, chronic kidney disease, and premature mortality and disability. The presence of both conditions has an amplifying effect on risk for microvascular and macrovascular complications.1 The prevalence of diabetes is rising worldwide (Fig. 37.1). Both diabetes and hypertension disproportionately affect people in middle and low-income countries, and an estimated 70% of all cases of diabetes are found in these countries.2,3 In the United States alone, the total costs of care for diabetes and hypertension in the years 2012 and 2011 were 245 and 46 billion dollars, respectively.4,5 Therefore, there is a great potential for meaningful health and economic gains attached to prevention, detection, and intervention for diabetes and hypertension.

For example, the environmental trigger may be a virus or chemical toxin that upsets the normal function of the immune system. This may lead to the body’s immune system attacking itself. The normal beta cells in the pancreas may be attacked and destroyed. When approximately 90% of the beta cells are destroyed, symptoms of diabetes mellitus begin to appear. The exact cause and sequence is not fully understood but investigation and research into the disease continues.
The treatment of low blood sugar consists of administering a quickly absorbed glucose source. These include glucose containing drinks, such as orange juice, soft drinks (not sugar-free), or glucose tablets in doses of 15-20 grams at a time (for example, the equivalent of half a glass of juice). Even cake frosting applied inside the cheeks can work in a pinch if patient cooperation is difficult. If the individual becomes unconscious, glucagon can be given by intramuscular injection.
The World Health Organization recommends testing those groups at high risk[54] and in 2014 the USPSTF is considering a similar recommendation.[58] High-risk groups in the United States include: those over 45 years old; those with a first degree relative with diabetes; some ethnic groups, including Hispanics, African-Americans, and Native-Americans; a history of gestational diabetes; polycystic ovary syndrome; excess weight; and conditions associated with metabolic syndrome.[23] The American Diabetes Association recommends screening those who have a BMI over 25 (in people of Asian descent screening is recommended for a BMI over 23).[59]
Patients with type 2 diabetes can still make insulin, but not enough to control their glucose levels. Type 2 diabetes is therefore initially treated with a combination of lifestyle changes (diet and exercise) which reduce the need for insulin and therefore lower glucose levels. If this is insufficient to achieve good glucose control, a range of tablets are available. These include metformin and pioglitazone, which, like diet and exercise, reduce insulin requirements; sulphonylureas (e.g. gliclazide), which stimulate insulin secretion; DPP4 inhibitors (e.g sitagliptin) and GLP-1 agonists (e.g. liraglutide), which stimulate insulin production and reduce appetite; and SGLT2 inhibitors (e.g. dapagliflozin), which lower blood sugar levels by causing sugar to pass out of the body in the urine. In many patients, particularly after several years of treatment, insulin production is so low or so insufficient compared with the patient's needs that patients with type 2 diabetes have to be treated with insulin injections, either alone or in combination with tablets.
Talk with your doctor about connecting with a certified diabetes educator and receiving diabetes self-management education. Learning about what to eat, what your medicines do, and how to test your blood sugars are just some of the things these resources can help with. Educators can also dispel myths, create meal plans, coordinate other doctors appointments for you, and listen to your needs. They are trained to teach using a patient-centered approach. They are your advocates who specialize in diabetes. Ask your doctor today or go to the American Association of Diabetes Educators website to find someone near you. Be sure to call your insurance company to see if these services are covered, too.
Diabetes mellitus type 2 is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency.[51] This is in contrast to diabetes mellitus type 1 in which there is an absolute insulin deficiency due to destruction of islet cells in the pancreas and gestational diabetes mellitus that is a new onset of high blood sugars associated with pregnancy.[13] Type 1 and type 2 diabetes can typically be distinguished based on the presenting circumstances.[48] If the diagnosis is in doubt antibody testing may be useful to confirm type 1 diabetes and C-peptide levels may be useful to confirm type 2 diabetes,[52] with C-peptide levels normal or high in type 2 diabetes, but low in type 1 diabetes.[53]
The classic symptoms of diabetes are polyuria (frequent urination), polydipsia (increased thirst), polyphagia (increased hunger), and weight loss.[23] Other symptoms that are commonly present at diagnosis include a history of blurred vision, itchiness, peripheral neuropathy, recurrent vaginal infections, and fatigue.[13] Many people, however, have no symptoms during the first few years and are diagnosed on routine testing.[13] A small number of people with type 2 diabetes mellitus can develop a hyperosmolar hyperglycemic state (a condition of very high blood sugar associated with a decreased level of consciousness and low blood pressure).[13]
Type 1 diabetes mellitus is predominantly a disease of the young, usually developing before 20 years of age. Overall, type I DM makes up approximately 15% of all cases of diabetes. It develops in approximately 1 in 600 children and is one of the most common chronic diseases in children. The incidence is relatively low for children under the age of 5, increases between 5 and 15, and then tapers off.
The treatment of low blood sugar consists of administering a quickly absorbed glucose source. These include glucose containing drinks, such as orange juice, soft drinks (not sugar-free), or glucose tablets in doses of 15-20 grams at a time (for example, the equivalent of half a glass of juice). Even cake frosting applied inside the cheeks can work in a pinch if patient cooperation is difficult. If the individual becomes unconscious, glucagon can be given by intramuscular injection.
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.
Type 2 diabetes is most common is those who are genetically predisposed and who are overweight, lead a sedentary lifestyle, have high blood pressure, and/or have insulin resistance due to excess weight. People of certain ethnicities are more likely to develop diabetes, too. These include: African Americans, Mexican Americans, American Indians, Native Hawaiians, Pacific Islanders, and Asian Americans. These populations are more likely to be overweight and have high blood pressure, which increases the risk of developing diabetes.
gestational diabetes diabetes mellitus with onset or first recognition during pregnancy, usually during the second or third trimester. In some cases mild, undetected glucose intolerance was present before pregnancy. It often disappears after the end of the pregnancy, but many women with this condition develop permanent diabetes mellitus in later life. Although the disordered carbohydrate metabolism is usually mild, prompt detection and treatment are necessary to avoid fetal and neonatal morbidity and mortality.
More common in adults, type 2 diabetes increasingly affects children as childhood obesity increases. There's no cure for type 2 diabetes, but you may be able to manage the condition by eating well, exercising and maintaining a healthy weight. If diet and exercise aren't enough to manage your blood sugar well, you also may need diabetes medications or insulin therapy.
Diet and moderate exercise are the first treatments implemented in diabetes. For many Type II diabetics, weight loss may be an important goal in helping them to control their diabetes. A well-balanced, nutritious diet provides approximately 50-60% of calories from carbohydrates, approximately 10-20% of calories from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on age, weight, and activity level. The calorie intake also needs to be distributed over the course of the entire day so surges of glucose entering the blood system are kept to a minimum.
A study by Dabelea et al found that in teenagers and young adults in whom diabetes mellitus had been diagnosed during childhood or adolescence, diabetes-related complications and comorbidities—including diabetic kidney disease, retinopathy, and peripheral neuropathy (but not arterial stiffness or hypertension)—were more prevalent in those with type 2 diabetes than in those with type 1 disease. [44]
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.[38]
In the sunshine, molecules in the skin are converted to vitamin D. But people stay indoors more these days, which could lead to vitamin D deficiency. Research shows that if mice are deprived of vitamin D, they are more likely to become diabetic. In people, observational studies have also found a correlation between D deficiency and type 1. "If you don't have enough D, then [your immune system] doesn't function like it should," says Chantal Mathieu, MD, PhD, a professor of experimental medicine and endocrinology at Katholieke Universiteit Leuven in Belgium. "Vitamin D is not the cause of type 1 diabetes. [But] if you already have a risk, you don't want to have vitamin D deficiency on board because that's going to be one of the little pushes that pushes you in the wrong direction."
What his theory boils down to is that type 2 diabetes is caused not by extra fat alone, but by fat stored in the wrong places. "Virtually all the individuals [with insulin resistance] have fat accumulation in liver and muscle," Shulman says, where it may disrupt normal biological processes, leading to insulin resistance. "If you can understand this, you can ideally come up with new ways to prevent insulin resistance and type 2 diabetes."
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.”
Beta cells are vulnerable to more than just bad genes, which may explain the associations between type 2 diabetes and environmental factors that aren't related to how much fat a body has or where it is stored. Beta cells carry vitamin D receptors on their surface, and people with vitamin D deficiency are at increased risk for type 2. Plus, several studies have shown that people with higher levels of toxic substances in their blood—such as from the PCBs found in fish fat—are at increased risk of type 2 diabetes, though a cause-and-effect relationship hasn't been proved. (Toxic substances and vitamin D have also been implicated in type 1 diabetes, but the disease mechanism may be unrelated to what's going on in type 2.)
Because both yeast and bacteria multiply more quickly when blood sugar levels are elevated, women with diabetes are overall at a higher risk of feminine health issues, such as bacterial infections, yeast infections, and vaginal thrush, especially when blood sugar isn't well controlled. And a lack of awareness about having prediabetes or diabetes can make managing blood sugar impossible.