ORAL GLUCOSE TOLERANCE TEST. Blood samples are taken from a vein before and after a patient drinks a thick, sweet syrup of glucose and other sugars. In a non-diabetic, the level of glucose in the blood goes up immediately after the drink and then decreases gradually as insulin is used by the body to metabolize, or absorb, the sugar. In a diabetic, the glucose in the blood goes up and stays high after drinking the sweetened liquid. A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher at two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes.
Diabetes can be looked for by testing a urine sample for sugar but for a diagnosis, a blood sample is required. This may be a simple measurement of the sugar level, usually fasting. Alternatively, a test called an HbA1c can be used which estimates sugar levels over the past couple of months. If someone has typical symptoms of diabetes, only a single abnormal test is required. Where there are no symptoms, a second confirmatory test is required. Sometimes, particularly in pregnancy, a glucose tolerance test is performed which involves blood tests before and 2 hours after a sugary drink.
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.

Insulin, a hormone released from the pancreas (an organ behind the stomach that also produces digestive enzymes), controls the amount of glucose in the blood. Glucose in the bloodstream stimulates the pancreas to produce insulin. Insulin helps glucose to move from the blood into the cells. Once inside the cells, glucose is converted to energy, which is used immediately, or the glucose is stored as fat or glycogen until it is needed.
In an otherwise healthy individual, blood glucose levels usually do not rise above 180 mg/dL (9 mmol/L). In a child with diabetes, blood sugar levels rise if insulin is insufficient for a given glucose load. The renal threshold for glucose reabsorption is exceeded when blood glucose levels exceed 180 mg/dL (10 mmol/L), causing glycosuria with the typical symptoms of polyuria and polydipsia. (See Pathophysiology, Clinical, and Treatment.)
Type 2 diabetes is believed to have a strong genetic link, meaning that it tends to run in families. Several genes are being studied that may be related to the cause of type 2 diabetes. If you have any of the following type 2 diabetes risk factors, it’s important to ask your doctor about a diabetes test. With a proper diabetes diet and healthy lifestyle habits, along with diabetes medication, if necessary, you can manage type 2 diabetes just like you manage other areas of your life. Be sure to continue seeking the latest information on type 2 diabetes as you become your own health advocate.

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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’s not uncommon for patients to suddenly feel unsteady and immediately need to reach for carbs, says Marjorie Cypress, a nurse practitioner at an endocrinology clinic in Albuquerque, New Mexico, and 2014 president of health care and education for the American Diabetes Association. “When you have high blood sugar, your body has a problem regulating its glucose,” she explains. “If you’ve eaten something high in carbohydrates, your body shoots out a little too much insulin, and your glucose drops quickly. This makes you feel shaky, and you tend to crave carbs or sugar. This can lead to a vicious cycle.” These are the best foods for someone on a diabetic diet.
Sources of complex carbohydrates include whole-wheat bread and brown rice, legumes like black beans, and quinoa. These foods contain fiber, vitamins, and minerals that are appropriate for any eating plan, regardless of whether you have prediabetes, have diabetes, or are perfectly healthy. In fact, experts know including complex carbs in your daily diet can help you maintain a healthy weight, among other health benefits.
After eating carbohydrates, the carbs break down into sugar, trigger the pancreas to produce insulin and are then stored in liver and muscles. However, there is a limit to the amount of sugar the liver and muscles can store. The easiest way to understand this is to think of your liver and muscles as small closets without much storage space. If sugar keeps coming in, the closet will quickly fill up.
Type 2 diabetes is mainly caused by insulin resistance. This means no matter how much or how little insulin is made, the body can't use it as well as it should. As a result, glucose can't be moved from the blood into cells. Over time, the excess sugar in the blood gradually poisons the pancreas causing it to make less insulin and making it even more difficult to keep blood glucose under control.
1. Monitoring of blood glucose status. In the past, urine testing was an integral part of the management of diabetes, but it has largely been replaced in recent years by self monitoring of blood glucose. Reasons for this are that blood testing is more accurate, glucose in the urine shows up only after the blood sugar level is high, and individual renal thresholds vary greatly and can change when certain medications are taken. As a person grows older and the kidney is less able to eliminate sugar in the urine, the renal threshold rises and less sugar is spilled into the urine. The position statement of the American Diabetes Association on Tests of Glycemia in Diabetes notes that urine testing still plays a role in monitoring in type 1 and gestational diabetes, and in pregnancy with pre-existing diabetes, as a way to test for ketones. All people with diabetes should test for ketones during times of acute illness or stress and when blood glucose levels are consistently elevated.
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.
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.
The most common complication of treating high blood glucose levels is low blood glucose levels (hypoglycemia). The risk is greatest for older people who are frail, who are sick enough to require frequent hospital admissions, or who are taking several drugs. Of all available drugs to treat diabetes, long-acting sulfonylurea drugs are most likely to cause low blood glucose levels in older people. When they take these drugs, they are also more likely to have serious symptoms, such as fainting and falling, and to have difficulty thinking or using parts of the body due to low blood glucose levels.
There are many complications of diabetes. Knowing and understanding the signs of these complications is important. If caught early, some of these complications can be treated and prevented from getting worse. The best way to prevent complications of diabetes is to keep your blood sugars in good control. High glucose levels produce changes in the blood vessels themselves, as well as in blood cells (primarily erythrocytes) that impair blood flow to various organs.
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.
Family or personal history. Your risk increases if you have prediabetes — a precursor to type 2 diabetes — or if a close family member, such as a parent or sibling, has type 2 diabetes. You're also at greater risk if you had gestational diabetes during a previous pregnancy, if you delivered a very large baby or if you had an unexplained stillbirth.
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