Before blood glucose levels rise, the body of a person destined for type 2 becomes resistant to insulin, much as bacteria can become resistant to antibiotics. Insulin is the signal for the muscles, fat, and liver to absorb glucose from the blood. As the body becomes resistant to insulin, the beta cells in the pancreas must pump out more of the hormone to compensate. People with beta cells that can't keep up with insulin resistance develop the high blood glucose of type 2 diabetes.
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.
For people who want to avoid drugs, taking an aggressive approach to healthy eating plan and lifestyle change is an option. It isn't easy, but if someone is very committed and motivated, lifestyle changes can be enough to maintain a healthy blood sugar level and to lose weight. Learning about a healthy diabetes diet (a low glycemic load diet) can be an good place to start.
A second theory, dubbed the hygiene hypothesis, blames the rise of type 1 on a society that's too clean. Good housekeeping and hygiene habits mean far fewer interactions with germs, which in turn may foster an immune system prone to going awry. "In a developing country, you have more infectious disease. This is associated with a lower risk of type 1 diabetes," says Li Wen, MD, PhD, an immunologist at the Yale University School of Medicine. In her lab, rodents raised in hyper-clean environments are more likely to get type 1 than those reared in dirtier cages.
The definition of a genetic disease is a disorder or condition caused by abnormalities in a person's genome. Some types of genetic inheritance include single inheritance, including cystic fibrosis, sickle cell anemia, Marfan syndrome, and hemochromatosis. Other types of genetic diseases include multifactorial inheritance. Still other types of genetic diseases include chromosome abnormalities (for example, Turner syndrome, and Klinefelter syndrome), and mitochondrial inheritance (for example, epilepsy and dementia).
No single environmental trigger has been identified as causing diabetes mellitus, however both infectious agents and dietary factors are thought to be important. Various viruses have been implicated in the development of type I DM. They may act by initiating or modifying the autoimmune process. In particular, the rubella virus and coxsackie viruses have been closely studied. In particular, congenital rubella infection has shown direct relationships with the development of type 1 diabetes mellitus. This is presumably due to the virus (or antibodies against it) damaging the beta cells of the pancreas. Some research has looked at dietary factors that may be associated with type 1 diabetes. In particular, cow’s milk proteins (such as bovine serum albumin) which may have some similarities to pancreatic islet cell markers may be able to trigger the autoimmune process. Other chemicals including nitrosamines have been identified as causes of diabetes mellitus in animal models, but not in humans.

What are symptoms of type 2 diabetes in children? Type 2 diabetes is becoming increasingly common in children, and this is linked to a rise in obesity. However, the condition can be difficult to detect in children because it develops gradually. Symptoms, treatment, and prevention of type 2 diabetes are similar in children and adults. Learn more here. Read now
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.
A random blood sugar of greater than 11.1 mmol/l (200 mg/dl) in association with typical symptoms[23] or a glycated hemoglobin (HbA1c) of ≥ 48 mmol/mol (≥ 6.5 DCCT %) is another method of diagnosing diabetes.[10] In 2009 an International Expert Committee that included representatives of the American Diabetes Association (ADA), the International Diabetes Federation (IDF), and the European Association for the Study of Diabetes (EASD) recommended that a threshold of ≥ 48 mmol/mol (≥ 6.5 DCCT %) should be used to diagnose diabetes.[48] This recommendation was adopted by the American Diabetes Association in 2010.[49] Positive tests should be repeated unless the person presents with typical symptoms and blood sugars >11.1 mmol/l (>200 mg/dl).[48]

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.
a broadly applied term used to denote a complex group of syndromes that have in common a disturbance in the oxidation and utilization of glucose, which is secondary to a malfunction of the beta cells of the pancreas, whose function is the production and release of insulin. Because insulin is involved in the metabolism of carbohydrates, proteins and fats, diabetes is not limited to a disturbance of glucose homeostasis alone.
Injections of insulin may either be added to oral medication or used alone.[24] Most people do not initially need insulin.[13] When it is used, a long-acting formulation is typically added at night, with oral medications being continued.[23][24] Doses are then increased to effect (blood sugar levels being well controlled).[24] When nightly insulin is insufficient, twice daily insulin may achieve better control.[23] The long acting insulins glargine and detemir are equally safe and effective,[98] 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.[99] In those who are pregnant insulin is generally the treatment of choice.[23]
To treat diabetic retinopathy, a laser is used to destroy and prevent the recurrence of the development of these small aneurysms and brittle blood vessels. Approximately 50% of patients with diabetes will develop some degree of diabetic retinopathy after 10 years of diabetes, and 80% retinopathy after 15 years of the disease. Poor control of blood sugar and blood pressure further aggravates eye disease in diabetes.

What you need to know about borderline diabetes Borderline diabetes, known as prediabetes, is a condition where blood sugar levels are higher than normal but not yet high enough to be type 2 diabetes. This MNT Knowledge Center article explains the signs to look out for, how to monitor the disease, and ways to prevent it becoming full diabetes. Read now
^ 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.
How to use basal insulin: Benefits, types, and dosage Basal, or background, insulin helps regulate blood sugar levels in people diagnosed with diabetes. It keeps glucose levels steady throughout the day and night. It is taken as injections, once a day or more often. The type of insulin and number of daily injections varies. Find out more about the options available. Read now
We give you special kudos for managing your condition, as it is not always easy. If you've had diabetes for a long time, it's normal to burn out sometimes. You may get tired of your day to day tasks, such as counting carbohydrates or measuring your blood sugar. Lean on a loved one or a friend for support, or consider talking to someone else who has diabetes who can provide, perhaps, an even more understanding ear or ideas that can help you.
What does the research say about proactive type 2 diabetes management? Research shows that proactive management can pay off in fewer complications down the road. In the landmark UKPDS study, 5,102 patients newly diagnosed with type 2 diabetes were followed for an average of 10 years to determine whether intensive use of blood glucose-lowering drugs would result in health benefits. Tighter average glucose control (an A1c of 7.0% vs. an A1c of 7.9%) reduced the rate of complications in the eyes, kidneys, and nervous system, by 25%. For every percentage point decrease in A1c (e.g., from 9% to 8%), there was a 25% reduction in diabetes-related deaths, and an 18% reduction in combined fatal and nonfatal heart attacks.
Type 2 diabetes, the most common type of diabetes, is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes mainly from the food you eat. Insulin, a hormone made by the pancreas, helps glucose get into your cells to be used for energy. In type 2 diabetes, your body doesn’t make enough insulin or doesn’t use insulin well. Too much glucose then stays in your blood, and not enough reaches your cells.
Jump up ^ Emadian A, Andrews RC, England CY, Wallace V, Thompson JL (November 2015). "The effect of macronutrients on glycaemic control: a systematic review of dietary randomised controlled trials in overweight and obese adults with type 2 diabetes in which there was no difference in weight loss between treatment groups". The British Journal of Nutrition. 114 (10): 1656–66. doi:10.1017/S0007114515003475. PMC 4657029. PMID 26411958.

Jump up ^ Haw, JS; Galaviz, KI; Straus, AN; Kowalski, AJ; Magee, MJ; Weber, MB; Wei, J; Narayan, KMV; Ali, MK (6 November 2017). "Long-term Sustainability of Diabetes Prevention Approaches: A Systematic Review and Meta-analysis of Randomized Clinical Trials". JAMA Internal Medicine. 177 (12): 1808–17. doi:10.1001/jamainternmed.2017.6040. PMID 29114778.
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.
Merck & Co., Inc., Kenilworth, NJ, USA is a global healthcare leader working to help the world be well. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Merck Manual was first published in 1899 as a service to the community. The legacy of this great resource continues as the Merck Manual in the US and Canada and the MSD Manual outside of North America. Learn more about our commitment to Global Medical Knowledge.
Some cases of diabetes are caused by the body's tissue receptors not responding to insulin (even when insulin levels are normal, which is what separates it from type 2 diabetes); this form is very uncommon. Genetic mutations (autosomal or mitochondrial) can lead to defects in beta cell function. Abnormal insulin action may also have been genetically determined in some cases. Any disease that causes extensive damage to the pancreas may lead to diabetes (for example, chronic pancreatitis and cystic fibrosis). Diseases associated with excessive secretion of insulin-antagonistic hormones can cause diabetes (which is typically resolved once the hormone excess is removed). Many drugs impair insulin secretion and some toxins damage pancreatic beta cells. The ICD-10 (1992) diagnostic entity, malnutrition-related diabetes mellitus (MRDM or MMDM, ICD-10 code E12), was deprecated by the World Health Organization (WHO) when the current taxonomy was introduced in 1999.[53]
Hyperglycemia (ie, random blood glucose concentration of more than 200 mg/dL or 11 mmol/L) results when insulin deficiency leads to uninhibited gluconeogenesis and prevents the use and storage of circulating glucose. The kidneys cannot reabsorb the excess glucose load, causing glycosuria, osmotic diuresis, thirst, and dehydration. Increased fat and protein breakdown leads to ketone production and weight loss. Without insulin, a child with type 1 diabetes mellitus wastes away and eventually dies due to DKA. The effects of insulin deficiency are shown in the image below.
Then, your blood sugar levels get too high. High blood sugar can have a deleterious effect on many parts of your body, including heart, blood vessels, nerves, eyes, and kidneys. Those who are overweight, don’t exercise enough, or have a history of type 2 diabetes in their family are more likely to get the disease. Maintaining a healthy weight, eating a healthy diet, and getting enough exercise can prevent type 2 diabetes. If you have a history of diabetes in your family, or if you are overweight, stay ahead of the disease by making healthy lifestyle choices and changing your diet.
Sugar doesn't cause diabetes. But there is one way that sugar can influence whether a person gets type 2 diabetes. Consuming too much sugar (or sugary foods and drinks) can make people put on weight. Gaining too much weight leads to type 2 diabetes in some people. Of course, eating too much sugar isn't the only cause of weight gain. Weight gain from eating too much of any food can make a person's chance of getting diabetes greater.
Rates of type 2 diabetes have increased markedly since 1960 in parallel with obesity.[17] As of 2015 there were approximately 392 million people diagnosed with the disease compared to around 30 million in 1985.[11][18] Typically it begins in middle or older age,[6] although rates of type 2 diabetes are increasing in young people.[19][20] Type 2 diabetes is associated with a ten-year-shorter life expectancy.[10] Diabetes was one of the first diseases described.[21] The importance of insulin in the disease was determined in the 1920s.[22]
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.
While poor vision is hardly uncommon—more than 60 percent of the American population wears glasses or contacts, after all—sudden changes in your vision, especially blurriness, need to be addressed by your doctor. Blurry vision is often a symptom of diabetes, as high blood sugar levels can cause swelling in the lenses of your eye, distorting your sight in the process. Fortunately, for many people, the effect is temporary and goes away when their blood sugar is being managed.
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.[37] All of these genes together still only account for 10% of the total heritable component of the disease.[37] 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]
Though not routinely used any longer, the oral glucose tolerance test (OGTT) is a gold standard for making the diagnosis of type 2 diabetes. It is still commonly used for diagnosing gestational diabetes and in conditions of pre-diabetes, such as polycystic ovary syndrome. With an oral glucose tolerance test, the person fasts overnight (at least eight but not more than 16 hours). Then first, the fasting plasma glucose is tested. After this test, the person receives an oral dose (75 grams) of glucose. There are several methods employed by obstetricians to do this test, but the one described here is standard. Usually, the glucose is in a sweet-tasting liquid that the person drinks. Blood samples are taken at specific intervals to measure the blood glucose.

Autonomic changes involving cardiovascular control (eg, heart rate, postural responses) have been described in as many as 40% of children with diabetes. Cardiovascular control changes become more likely with increasing duration and worsening control. [18] In a study by 253 patients with type 1 diabetes (mean age at baseline 14.4 y), Cho et al reported that the prevalence of cardiac autonomic dysfunction increases in association with higher body mass index and central adiposity. [19]
Type 1 diabetes is considered an autoimmune disease. With an autoimmune disease, your immune system – which helps protect your body from getting sick – is engaged in too little or too much activity. In Type 1 diabetes, beta cells, which are a kind of cell in the pancreas that produces insulin, are destroyed. Our bodies use insulin to take the sugar from carbohydrates we eat and create fuel. With Type 1 diabetes, your body does not produce insulin, and that's why you need to use insulin as part of your treatment.
Sugary breath isn’t as sweet as it seems.  Diabetics often notice that they’ve developed sweet or nail-polish-like breath before they’re diagnosed. However, if you’re dealing with this strange symptom, time is of the essence. Sweet breath is often a sign of diabetic ketoacidosis, a condition in which your body can’t effectively convert glucose into energy, keeping your blood sugar at dangerous—potentially fatal—levels if untreated.

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.
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