If genetics has taught us anything about diabetes, it's that, for most people, genes aren't the whole story. True, a few rare kinds of diabetes—including those collectively called MODY for maturity-onset diabetes of the young—have been traced to defects in a single gene. But for other types of diabetes, hereditary factors are still not well understood.

Type 1 diabetes occurs because the insulin-producing cells of the pancreas (beta cells) are damaged. In type 1 diabetes, the pancreas makes little or no insulin, so sugar cannot get into the body's cells for use as energy. People with type 1 diabetes must use insulin injections to control their blood glucose. Type 1 is the most common form of diabetes in people who are under age 30, but it can occur at any age. Ten percent of people with diabetes are diagnosed with type 1.
Insulin is a hormone that is produced by specialized cells (beta cells) of the pancreas. (The pancreas is a deep-seated organ in the abdomen located behind the stomach.) In addition to helping glucose enter the cells, insulin is also important in tightly regulating the level of glucose in the blood. After a meal, the blood glucose level rises. In response to the increased glucose level, the pancreas normally releases more insulin into the bloodstream to help glucose enter the cells and lower blood glucose levels after a meal. When the blood glucose levels are lowered, the insulin release from the pancreas is turned down. It is important to note that even in the fasting state there is a low steady release of insulin than fluctuates a bit and helps to maintain a steady blood sugar level during fasting. In normal individuals, such a regulatory system helps to keep blood glucose levels in a tightly controlled range. As outlined above, in patients with diabetes, the insulin is either absent, relatively insufficient for the body's needs, or not used properly by the body. All of these factors cause elevated levels of blood glucose (hyperglycemia).
According to the National Institutes of Health, the reported rate of gestational diabetes is between 2% to 10% of pregnancies. Gestational diabetes usually resolves itself after pregnancy. Having gestational diabetes does, however, put mothers at risk for developing type 2 diabetes later in life. Up to 10% of women with gestational diabetes develop type 2 diabetes. It can occur anywhere from a few weeks after delivery to months or years later.
Risk factors for type 2 diabetes include obesity, high cholesterol, high blood pressure, and physical inactivity. The risk of developing type 2 diabetes also increases as people grow older. People who are over 40 and overweight are more likely to develop type 2 diabetes, although the incidence of this type of diabetes in adolescents is growing. Diabetes is more common among Native Americans, African Americans, Hispanic Americans and Asian Americans/Pacific Islanders. Also, people who develop diabetes while pregnant (a condition called gestational diabetes) are more likely to develop type 2 diabetes later in life.
Threshold for diagnosis of diabetes is based on the relationship between results of glucose tolerance tests, fasting glucose or HbA1c and complications such as retinal problems.[10] A fasting or random blood sugar is preferred over the glucose tolerance test, as they are more convenient for people.[10] HbA1c has the advantages that fasting is not required and results are more stable but has the disadvantage that the test is more costly than measurement of blood glucose.[50] It is estimated that 20% of people with diabetes in the United States do not realize that they have the disease.[10]
[1] Diabetes Prevention Program Research Group. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. The Lancet Diabetes & Endocrinology. 2015;3(11):866‒875. You can find more information about this study on the Diabetes Prevention Program Outcomes Study website.
Insulin is the hormone responsible for reducing blood sugar. In order for insulin to work, our tissues have to be sensitive to its action; otherwise, tissues become resistant and insulin struggles to clear out sugar from the blood. As insulin resistance sets in, the first organ to stop responding to insulin is the liver, followed by the muscles and eventually fat. How does insulin resistance begin? The root of the problem is our diet.
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
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.
Diabetes mellitus is a diagnostic term for a group of disorders characterized by abnormal glucose homeostasis resulting in elevated blood sugar. There is variability in its manifestations, wherein some individuals have only asymptomatic glucose intolerance, while others present acutely with diabetic ketoacidosis, and still others develop chronic complications such as nephropathy, neuropathy, retinopathy, or accelerated atherosclerosis. It is among the most common of chronic disorders, affecting up to 5–10% of the adult population of the Western world. Its prevalence varies over the globe, with certain populations, including some American Indian tribes and the inhabitants of Micronesia and Polynesia, having extremely high rates of diabetes (1,2). The prevalence of diabetes is increasing dramatically and it has been estimated that the worldwide prevalence will increase by more than 50% between the years 2000 and 2030 (3).
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All types of diabetes mellitus have something in common. Normally, your body breaks down the sugars and carbohydrates you eat into a special sugar called glucose. Glucose fuels the cells in your body. But the cells need insulin, a hormone, in your bloodstream in order to take in the glucose and use it for energy. With diabetes mellitus, either your body doesn't make enough insulin, it can't use the insulin it does produce, or a combination of both.
Don’t be alarmed: This is not diabetic retinopathy, where the blood vessels in the back of the eye are getting destroyed, says Dr. Cypess. In the early stages of diabetes, the eye lens is not focusing well because glucose builds up in the eye, which temporarily changes its shape. “You’re not going blind from diabetes,” Dr. Cypess says he assures patients. “In about six to eight weeks after your blood sugars are stabilized, you’re not going to feel it anymore; the eye will adjust.” Here are more surprising facts you never knew about diabetes.

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.


Although this complication is not seen in pediatric patients, it is a significant cause of morbidity and premature mortality in adults with diabetes. People with type 1 diabetes mellitus have twice the risk of fatal myocardial infarction (MI) and stroke that people unaffected with diabetes do; in women, the MI risk is 4 times greater. People with type 1 diabetes mellitus also have 4 times greater risk for atherosclerosis.
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.
People with diabetes can benefit from education about the disease and treatment, good nutrition to achieve a normal body weight, and exercise, with the goal of keeping both short-term and long-term blood glucose levels within acceptable bounds. In addition, given the associated higher risks of cardiovascular disease, lifestyle modifications are recommended to control blood pressure.[80][81]
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.

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.
Sasigarn A Bowden, MD Associate Professor of Pediatrics, Section of Pediatric Endocrinology, Metabolism and Diabetes, Department of Pediatrics, Ohio State University College of Medicine; Pediatric Endocrinologist, Associate Fellowship Program Director, Division of Endocrinology, Nationwide Children’s Hospital; Affiliate Faculty/Principal Investigator, Center for Clinical Translational Research, Research Institute at Nationwide Children’s Hospital
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.
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.
Previously, CGMs required frequent calibration with fingerstick glucose testing. Also their results were not accurate enough so that people always had to do a fingerstick to verify a reading on their CGM before calculating a dose of insulin (for example before meals or to correct a high blood sugar). However, recent technological advances have improved CGMs. One professional CGM can be worn for up to 14 days without calibration. Another personal CGM can be used to guide insulin dosing without confirmation by fingerstick glucose. Finally, there are now systems in which the CGM device communicates with insulin pumps to either stop delivery of insulin when blood glucose is dropping (threshold suspend), or to give daily insulin (hybrid closed loop system).
Diabetic neuropathy is probably the most common complication of diabetes. Studies suggest that up to 50% of people with diabetes are affected to some degree. Major risk factors of this condition are the level and duration of elevated blood glucose. Neuropathy can lead to sensory loss and damage to the limbs. It is also a major cause of impotence in diabetic men.

Insulin is the hormone responsible for reducing blood sugar. In order for insulin to work, our tissues have to be sensitive to its action; otherwise, tissues become resistant and insulin struggles to clear out sugar from the blood. As insulin resistance sets in, the first organ to stop responding to insulin is the liver, followed by the muscles and eventually fat. How does insulin resistance begin? The root of the problem is our diet.
People with type 2 diabetes have insulin resistance, which means the body cannot use insulin properly to help glucose get into the cells. In people with type 2 diabetes, insulin doesn’t work well in muscle, fat, and other tissues, so your pancreas (the organ that makes insulin) starts to put out a lot more of it to try and compensate. "This results in high insulin levels in the body,” says Fernando Ovalle, MD, director of the multidisciplinary diabetes clinic at the University of Alabama in Birmingham. This insulin level sends signals to the brain that your body is hungry.
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