Prediabetes is a condition in which blood glucose levels are higher than normal, but a person does not yet have diabetes. Prediabetes and high blood glucose levels are a risk factor for developing diabetes, heart disease, and other health problems. Other warning signs prediabetes may include increased urination, feeling you need to urinate more often, and/or increased thirst.
From a dental perspective, pregnancy leads to hormonal changes that increase the mother’s risk of developing gingivitis and gingival lesions called pregnancy tumors (see Right). Not surprisingly, poor glycemic control further adds to this risk. Therefore, it is imperative that if you become pregnant, you should promptly see your dentist. He or she will work with you to ensure that your dental self-care regimen is maximized to prevent or control your dental disease. Additional Resources on Diabetes and Oral Health National Institute of Dental and Craniofacial Research www.nidcr.nih.gov American Diabetes Association www.diabetes.org American Dental Association www.dental.org American Academy of Periodontology www.perio.org The Diabetes Monitor www.diabetesmonitor.com David Mendosa www.mendosa.com Diatribe www.diatribe.us The information contained in this monograph is for educational purposes only. This information is not a substitute for professional medical advice, diagnosis, or treatment. If you have or suspect you may have a health concern, consult your professional health care provider. Reliance on any information provided in this monograph is solely at your own risk.
Exposure to certain viral infections (mumps and Coxsackie viruses) or other environmental toxins may serve to trigger abnormal antibody responses that cause damage to the pancreas cells where insulin is made. Some of the antibodies seen in type 1 diabetes include anti-islet cell antibodies, anti-insulin antibodies and anti-glutamic decarboxylase antibodies. These antibodies can be detected in the majority of patients, and may help determine which individuals are at risk for developing type 1 diabetes.
Dietary factors also influence the risk of developing type 2 diabetes. Consumption of sugar-sweetened drinks in excess is associated with an increased risk.[32][33] The type of fats in the diet are important, with saturated fats and trans fatty acids increasing the risk, and polyunsaturated and monounsaturated fat decreasing the risk.[26] Eating a lot of white rice appears to play a role in increasing risk.[34] A lack of exercise is believed to cause 7% of cases.[35] Persistent organic pollutants may play a role.[36]
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.

The development of type 2 diabetes is caused by a combination of lifestyle and genetic factors.[24][26] While some of these factors are under personal control, such as diet and obesity, other factors are not, such as increasing age, female gender, and genetics.[10] A lack of sleep has been linked to type 2 diabetes.[27] This is believed to act through its effect on metabolism.[27] The nutritional status of a mother during fetal development may also play a role, with one proposed mechanism being that of DNA methylation.[28] The intestinal bacteria Prevotella copri and Bacteroides vulgatus have been connected with type 2 diabetes.[29]
Scientists have done studies of twins to help estimate how important genes are in determining one's risk of developing diabetes. Identical twins have identical genes and thus the same genetic risk for a disease. Research has found that if one identical twin has type 1 diabetes, the chance that the other twin will get the disease is roughly 40 or 50 percent. For type 2 diabetes, that risk goes up to about 80 or 90 percent. This might suggest that genes play a bigger role in type 2 than in type 1, but that isn't necessarily so. Type 2 is far more common in the general population than type 1, which means that regardless of genetics both twins are more likely to develop type 2 diabetes.
Rosiglitazone, a thiazolidinedione, has not been found to improve long-term outcomes even though it improves blood sugar levels.[93] Additionally it is associated with increased rates of heart disease and death.[94] Angiotensin-converting enzyme inhibitors (ACEIs) prevent kidney disease and improve outcomes in those with diabetes.[95][96] The similar medications angiotensin receptor blockers (ARBs) do not.[96] A 2016 review recommended treating to a systolic blood pressure of 140 to 150 mmHg.[97]

When you have Type 2 diabetes, you may start out with something called insulin resistance. This means your cells do not respond well to the insulin you are making. "Insulin levels may be quite high, especially in the early stages of the disease. Eventually, your pancreas may not be able to keep up, and insulin secretion goes down," Rettinger explains. Insulin resistance becomes more common as you put on more weight, especially weight around your belly.


Because people with type 2 diabetes produce some insulin, ketoacidosis does not usually develop even when type 2 diabetes is untreated for a long time. Rarely, the blood glucose levels become extremely high (even exceeding 1,000 mg/dL). Such high levels often happen as the result of some superimposed stress, such as an infection or drug use. When the blood glucose levels get very high, people may develop severe dehydration, which may lead to mental confusion, drowsiness, and seizures, a condition called hyperosmolar hyperglycemic state. Currently, many people with type 2 diabetes are diagnosed by routine blood glucose testing before they develop such severely high blood glucose levels.


As with many conditions, treatment of type 2 diabetes begins with lifestyle changes, particularly in your diet and exercise. If you have type 2 diabetes, speak to your doctor and diabetes educator about an appropriate diet. You may be referred to a dietitian. It is also a good idea to speak with your doctor before beginning an exercise program that is more vigourous than walking to determine how much and what kind of exercise is appropriate.
Morbidity and mortality stem from the metabolic derangements and from the long-term complications that affect small and large vessels, resulting in retinopathy, nephropathy, neuropathy, ischemic heart disease, and arterial obstruction with gangrene of extremities.2 The acute clinical manifestations can be fully understood in the context of current knowledge of the secretion and action of insulin.3 Genetic and other etiologic considerations implicate autoimmune mechanisms in the evolution of the most common form of childhood diabetes, known as type 1a diabetes.4,5 Genetic defects in insulin secretion are increasingly recognized and understood as defining the causes of monogenic forms of diabetes such as maturity-onset diabetes of youth (MODY) and neonatal DM and contributing to the spectrum of T2DM.6

About 84 million adults in the US (more than 1 out of 3) have prediabetes, and about 90% do not know they have it until a routine blood test is ordered, or symptoms of type 2 diabetes develop. For example, excessive thirst, frequent urination, and unexplained weight loss. If you have prediabetes also it puts you at risk for heart attack, stroke, and type 2 diabetes.
Jump up ^ Qaseem, Amir; Wilt, Timothy J.; Kansagara, Devan; Horwitch, Carrie; Barry, Michael J.; Forciea, Mary Ann (6 March 2018). "Hemoglobin A Targets for Glycemic Control With Pharmacologic Therapy for Nonpregnant Adults With Type 2 Diabetes Mellitus: A Guidance Statement Update From the American College of Physicians". Annals of Internal Medicine. doi:10.7326/M17-0939.
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.

Although the signs of diabetes can begin to show early, sometimes it takes a person a while to recognize the symptoms. This often makes it seem like signs and symptoms of diabetes appear suddenly. That’s why it’s important to pay attention to your body, rather than simply brushing them off. To that end, here are some type 1 and type 2 diabetes symptoms that you may want to watch out for:

There are many types of sugar. Some sugars are simple, and others are complex. Table sugar (sucrose) is made of two simpler sugars called glucose and fructose. Milk sugar (lactose) is made of glucose and a simple sugar called galactose. The carbohydrates in starches, such as bread, pasta, rice, and similar foods, are long chains of different simple sugar molecules. Sucrose, lactose, carbohydrates, and other complex sugars must be broken down into simple sugars by enzymes in the digestive tract before the body can absorb them.
Type 1 diabetes is partly inherited, with multiple genes, including certain HLA genotypes, known to influence the risk of diabetes. In genetically susceptible people, the onset of diabetes can be triggered by one or more environmental factors,[41] such as a viral infection or diet. Several viruses have been implicated, but to date there is no stringent evidence to support this hypothesis in humans.[41][42] Among dietary factors, data suggest that gliadin (a protein present in gluten) may play a role in the development of type 1 diabetes, but the mechanism is not fully understood.[43][44]

^ Jump up to: a b Picot J, Jones J, Colquitt JL, Gospodarevskaya E, Loveman E, Baxter L, Clegg AJ (September 2009). "The clinical effectiveness and cost-effectiveness of bariatric (weight loss) surgery for obesity: a systematic review and economic evaluation". Health Technology Assessment. 13 (41): 1–190, 215–357, iii–iv. doi:10.3310/hta13410. PMID 19726018.
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.
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.
The roots of type 2 diabetes remain in insulin resistance and pancreatic failure, and the blame for the current diabetes epidemic lies in an overall dietary pattern emphasizing meat, dairy products, and fatty foods, aided and abetted by sugary foods and beverages, rather than simply in sugar alone. A diet emphasizing vegetables, fruits, whole grains, and legumes and avoiding animal products helps prevent diabetes and improves its management when it has been diagnosed. 
Type 1 diabetes is partly inherited, with multiple genes, including certain HLA genotypes, known to influence the risk of diabetes. In genetically susceptible people, the onset of diabetes can be triggered by one or more environmental factors,[41] such as a viral infection or diet. Several viruses have been implicated, but to date there is no stringent evidence to support this hypothesis in humans.[41][42] Among dietary factors, data suggest that gliadin (a protein present in gluten) may play a role in the development of type 1 diabetes, but the mechanism is not fully understood.[43][44]
Treatment of high blood pressure and high cholesterol levels, which can contribute to circulation problems, can help prevent some of the complications of diabetes as well. A low dose of aspirin taken daily is recommended in people with risk factors for heart disease. All people with diabetes who are between 40 and 75 years are given a statin (a drug to decrease cholesterol levels) regardless of cholesterol levels. Younger people with an elevated risk of heart disease should also take a statin .
^ Jump up to: a b Cheng, J; Zhang, W; Zhang, X; Han, F; Li, X; He, X; Li, Q; Chen, J (May 2014). "Effect of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on all-cause mortality, cardiovascular deaths, and cardiovascular events in patients with diabetes mellitus: a meta-analysis". JAMA Internal Medicine. 174 (5): 773–85. doi:10.1001/jamainternmed.2014.348. PMID 24687000.
To measure blood glucose levels, a blood sample is usually taken after people have fasted overnight. However, it is possible to take blood samples after people have eaten. Some elevation of blood glucose levels after eating is normal, but even after a meal the levels should not be very high. Fasting blood glucose levels should never be higher than 125 mg/dL. Even after eating, blood glucose levels should not be higher than 199 mg/dL.

Diabetes mellitus (diabetes) is a common chronic disease of abnormal carbohydrate, fat, and protein metabolism that affects an estimated 20 million people in the United States, of whom about one third are undiagnosed. There are two major forms recognized, type-1 and type-2. Both are characterized by inappropriately high blood sugar levels (hyperglycemia). In type-1 diabetes the patient can not produce the hormone insulin, while in type-2 diabetes the patient produces insulin, but it is not used properly. An estimated 90% of diabetic patients suffer from type-2 disease. The causes of diabetes are multiple and both genetic and environmental factors contribute to its development. The genetic predisposition for type-2 diabetes is very strong and numerous environmental factors such as diet, lack of exercise, and being overweight are known to also increase one’s risk for diabetes. Diabetes is a dangerous disease which affects the entire body and diabetic patients are at increased risk for heart disease, hypertension, stroke, kidney failure, blindness, neuropathy, and infection when compared to nondiabetic patients. Diabetic patients also have impaired healing when compared to healthy individuals. This is in part due to the dysfunction of certain white blood cells that fight infection.
Diabetes mellitus results mainly from a deficiency or diminished effectiveness of insulin that is normally produced by the beta cells of the pancreas. It is characterised by high blood sugar, altered sugar and glucose metabolism and this affects blood vessels and causes several organ damage. Causes of diabetes can be classified according to the types of diabetes.
Regarding age, data shows that for each decade after 40 years of age regardless of weight there is an increase in incidence of diabetes. The prevalence of diabetes in persons 65 years of age and older is around 25%. Type 2 diabetes is also more common in certain ethnic groups. Compared with a 7% prevalence in non-Hispanic Caucasians, the prevalence in Asian Americans is estimated to be 8.0%, in Hispanics 13%, in blacks around 12.3%, and in certain Native American communities 20% to 50%. Finally, diabetes occurs much more frequently in women with a prior history of diabetes that develops during pregnancy (gestational diabetes).
Type 2 diabetes which accounts for 85-95 per cent of all diabetes has a latent, asymptomatic period of sub-clinical stages which often remains undiagnosed for several years1. As a result, in many patients the vascular complications are already present at the time of diagnosis of diabetes, which is often detected by an opportunistic testing. Asian populations in general, particularly Asian Indians have a high risk of developing diabetes at a younger age when compared with the western populations5. Therefore, it is essential that efforts are made to diagnose diabetes early so that the long term sufferings by the patients and the societal burden can be considerably mitigated.
A chronic metabolic disorder marked by hyperglycemia. DM results either from failure of the pancreas to produce insulin (type 1 DM) or from insulin resistance, with inadequate insulin secretion to sustain normal metabolism (type 2 DM). Either type of DM may damage blood vessels, nerves, kidneys, the retina, and the developing fetus and the placenta during pregnancy. Type 1 or insulin-dependent DM has a prevalence of just 0.3 to 0.4%. Type 2 DM (formerly called adult-onset DM) has a prevalence in the general population of 6.6%. In some populations (such as older persons, Native Americans, African Americans, Pacific Islanders, Mexican Americans), it is present in nearly 20% of adults. Type 2 DM primarily affects obese middle-aged people with sedentary lifestyles, whereas type 1 DM usually occurs in children, most of whom are active and thin, although extremely obese children are now being diagnosed with type 2 diabetes as well. See: table; dawn phenomenon; insulin; insulin pump; insulin resistance; diabetic polyneuropathy; Somogyi phenomenon
When you have diabetes, your body becomes less efficient at breaking food down into sugar, so you have more sugar sitting in your bloodstream, says Dobbins. “Your body gets rid of it by flushing it out in the urine.” So going to the bathroom a lot could be one of the diabetes symptoms you’re missing. Most patients aren’t necessarily aware of how often they use the bathroom, says Dr. Cypess. “When we ask about it, we often hear, ‘Oh yeah, I guess I’m going more often than I used to,’” he says. But one red flag is whether the need to urinate keeps you up at night. Once or twice might be normal, but if it’s affecting your ability to sleep, that could be a diabetes symptom to pay attention to. Make sure you know these diabetes myths that could sabotage your health.

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.
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.
Treatment of high blood pressure and high cholesterol levels, which can contribute to circulation problems, can help prevent some of the complications of diabetes as well. A low dose of aspirin taken daily is recommended in people with risk factors for heart disease. All people with diabetes who are between 40 and 75 years are given a statin (a drug to decrease cholesterol levels) regardless of cholesterol levels. Younger people with an elevated risk of heart disease should also take a statin .
In type 2 diabetes (formerly called non– insulin-dependent diabetes or adult-onset diabetes), the pancreas often continues to produce insulin, sometimes even at higher-than-normal levels, especially early in the disease. However, the body develops resistance to the effects of insulin, so there is not enough insulin to meet the body’s needs. As type 2 diabetes progresses, the insulin-producing ability of the pancreas decreases.
Managing your blood glucose, blood pressure, and cholesterol, and quitting smoking if you smoke, are important ways to manage your type 2 diabetes. Lifestyle changes that include planning healthy meals, limiting calories if you are overweight, and being physically active are also part of managing your diabetes. So is taking any prescribed medicines. Work with your health care team to create a diabetes care plan that works for you.
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.

The prognosis of diabetes is related to the extent to which the condition is kept under control to prevent the development of the complications described in the preceding sections. Some of the more serious complications of diabetes such as kidney failure and cardiovascular disease, can be life-threatening. Acute complications such as diabetic ketoacidosis can also be life-threatening. As mentioned above, aggressive control of blood sugar levels can prevent or delay the onset of complications, and many people with diabetes lead long and full lives.


People with diabetes either don't make insulin or their body's cells no longer are able to use the insulin, leading to high blood sugars. By definition, diabetes is having a blood glucose level of greater than or equal to126 milligrams per deciliter (mg/dL) after an 8-hour fast (not eating anything), or by having a non-fasting glucose level greater than or equal to 200 mg/dL along with symptoms of diabetes, or a glucose level of greater than or equal to 200 mg/dL on a 2-hour glucose tolerance test, or an A1C greater than or equal to 6.5%. Unless the person is having obvious symptoms of diabetes or is in a diabetic crisis, the diagnosis must be confirmed with a repeat test.

Also striking are the differences in incidence between mainland Italy (8.4 cases per 100,000 population) and the Island of Sardinia (36.9 cases per 100,000 population). These variations strongly support the importance of environmental factors in the development of type 1 diabetes mellitus. Most countries report that incidence rates have at least doubled in the last 20 years. Incidence appears to increase with distance from the equator. [31]


Inhalable insulin has been developed.[125] The original products were withdrawn due to side effects.[125] Afrezza, under development by the pharmaceuticals company MannKind Corporation, was approved by the United States Food and Drug Administration (FDA) for general sale in June 2014.[126] An advantage to inhaled insulin is that it may be more convenient and easy to use.[127]
Insulin — the hormone that allows your body to regulate sugar in the blood — is made in your pancreas. Essentially, insulin resistance is a state in which the body’s cells do not use insulin efficiently. As a result, it takes more insulin than normal to transport blood sugar (glucose) into cells, to be used immediately for fuel or stored for later use. A drop in efficiency in getting glucose to cells creates a problem for cell function; glucose is normally the body’s quickest and most readily available source of energy.
Treatment of high blood pressure and high cholesterol levels, which can contribute to circulation problems, can help prevent some of the complications of diabetes as well. A low dose of aspirin taken daily is recommended in people with risk factors for heart disease. All people with diabetes who are between 40 and 75 years are given a statin (a drug to decrease cholesterol levels) regardless of cholesterol levels. Younger people with an elevated risk of heart disease should also take a statin .
Being too heavy gets the bulk of the blame for triggering type 2 diabetes. According to the National Institutes of Health, about 85 percent of people with type 2 diabetes are overweight or obese. But consider that the remaining 15 percent are not. Consider, too, that roughly two-thirds of overweight people and a third of those who are obese will never develop diabetes. In other words, normal-weight and thin people also develop type 2, while heavy people won't necessarily. Clearly, there is more to the connection between lifestyle and type 2 diabetes than just body size.
Excessive hunger goes hand-in-hand with fatigue and cell starvation. Because the cells are resistant to the body's insulin, glucose remains in the blood. The cells are then unable to gain access to glucose, which can trigger hunger hormones that tell the brain that you are hungry. Excessive eating can complicate things further by causing blood sugars to increase.
Infections. Poorly controlled diabetes can lead to a variety of tissue infections. The most commonly encountered is a yeast infection (Candida) and the presence of dry mouth further increases one’s risk (see PATIENT INFORMATION SHEET – Oral Yeast Infections). Typically, affected areas appear redder than the surrounding tissue and commonly affected sites include the tongue, palate, cheeks, gums, or corners of the mouth (see Right). There is conflicting data regarding cavity risk in the diabetic patient, but those who have dry mouth are clearly at increased risk for developing cavities.

Diabetes has been coined the “silent killer” because the symptoms are so easy to miss. Over 24 million people in America have diabetes, so this is no tiny issue. Kids years ago hardly ever knew another child with diabetes, but such is no longer the case. Approximately 1.25 million children in the United States living with diabetes, which is very telling for state of health in America in 2016 when children are having to endure a medical lifestyle at such a young age.


Diabetic foot disease, due to changes in blood vessels and nerves, often leads to ulceration and subsequent limb amputation. It is one of the most costly complications of diabetes, especially in communities with inadequate footwear. It results from both vascular and neurological disease processes. Diabetes is the most common cause of non-traumatic amputation of the lower limb, which may be prevented by regular inspection and good care of the foot.
The problem with sugar, regardless of type, is the sheer amount of it that’s found in the Standard American Diet (SAD), which is the typical eating plan many people in the United States — as well as those in an increasing number of modernized countries — have developed a taste for. When consumed in excess, foods in this category can lead to heart disease, stroke, and other serious health issues. “Often, foods with added sugar also contain fat,” explains Grieger, noting that these components go hand in hand when it comes to the risk for insulin resistance, the hallmark of type 2 diabetes.
Although there are dozens of known type 1 genes, about half of the risk attributable to heredity comes from a handful that coordinate a part of the immune system called HLA, which helps the body recognize nefarious foreign invaders, such as viruses, bacteria, and parasites. Type 1 diabetes is an autoimmune disease, in which the body's own immune system destroys the cells in the pancreas that produce insulin, so perhaps it is no surprise that immunity genes are involved. Other autoimmune diseases share the HLA gene link, which may be why people with type 1 are more likely to develop additional auto­immune disorders.

Diabetes can also result from other hormonal disturbances, such as excessive growth hormone production (acromegaly) and Cushing's syndrome. In acromegaly, a pituitary gland tumor at the base of the brain causes excessive production of growth hormone, leading to hyperglycemia. In Cushing's syndrome, the adrenal glands produce an excess of cortisol, which promotes blood sugar elevation.

Dietary factors also influence the risk of developing type 2 DM. Consumption of sugar-sweetened drinks in excess is associated with an increased risk.[46][47] The type of fats in the diet is also important, with saturated fat and trans fats increasing the risk and polyunsaturated and monounsaturated fat decreasing the risk.[45] Eating lots of white rice, and other starches, also may increase the risk of diabetes.[48] A lack of physical activity is believed to cause 7% of cases.[49]
Metformin is generally recommended as a first line treatment for type 2 diabetes, as there is good evidence that it decreases mortality.[6] It works by decreasing the liver's production of glucose.[87] Several other groups of drugs, mostly given by mouth, may also decrease blood sugar in type II DM. These include agents that increase insulin release, agents that decrease absorption of sugar from the intestines, and agents that make the body more sensitive to insulin.[87] When insulin is used in type 2 diabetes, a long-acting formulation is usually added initially, while continuing oral medications.[6] Doses of insulin are then increased to effect.[6][88]

Lifestyle factors are important to the development of type 2 diabetes, including obesity and being overweight (defined by a body mass index of greater than 25), lack of physical activity, poor diet, stress, and urbanization.[10][30] Excess body fat is associated with 30% of cases in those of Chinese and Japanese descent, 60–80% of cases in those of European and African descent, and 100% of cases in Pima Indians and Pacific Islanders.[13] Among those who are not obese, a high waist–hip ratio is often present.[13] Smoking appears to increase the risk of type 2 diabetes mellitus.[31]

Excess glucose in the blood can damage small blood vessels in the nerves causing a tingling sensation or pain in the fingers, toes and limbs. Nerves that lie outside of the central nervous system may also be damaged, which is referred to as peripheral neuropathy. If nerves of the gastrointestinal tract are affected, this may cause vomiting, constipation and diarrhea.


Impaired glucose tolerance (IGT) and impaired fasting glycaemia (IFG) refer to levels of blood glucose concentration above the normal range, but below those which are diagnostic for diabetes. Subjects with IGT and/or IFG are at substantially higher risk of developing diabetes and cardiovascular disease than those with normal glucose tolerance. The benefits of clinical intervention in subjects with moderate glucose intolerance is a topic of much current interest.
Jump up ^ Qaseem, Amir; Wilt, Timothy J.; Kansagara, Devan; Horwitch, Carrie; Barry, Michael J.; Forciea, Mary Ann (6 March 2018). "Hemoglobin A Targets for Glycemic Control With Pharmacologic Therapy for Nonpregnant Adults With Type 2 Diabetes Mellitus: A Guidance Statement Update From the American College of Physicians". Annals of Internal Medicine. doi:10.7326/M17-0939.
People with these risk factors should be screened for diabetes at least once every three years. Diabetes risk can be estimated using online risk calculators. Doctors may measure fasting blood glucose levels and hemoglobin A1C level, or do an oral glucose tolerance test. If the test results are on the border between normal and abnormal, doctors do the screening tests more often, at least once a year.
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.
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