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There are two major types of diabetes, Type 1 ("Juvenile diabetes" or "insulin-dependent diabetes mellitus") and Type 2 ("Adult onset" or "non-insulin dependent" diabetes mellitus (NIDDM). This article discusses a newer classification, Type 1.5.
Type 1.5 is one of several names now applied to those who are diagnosed with diabetes as adults, but who do not immediately require insulin for treatment, are often not overweight, and have little or no resistance to insulin. When special lab tests are done, they are found to have antibodies, especially GAD65 antibodies, that attack their beta cells. This sort of diabetes is sometimes called Slow Onset Type 1 or Latent Autoimmune Diabetes in Adults (LADA).
One study performed in Bruneck, Italy [Diabetes, October 1998] found that 84% of the people diagnosed as Type 2 had insulin resistance, but the other 16% did not, suggesting these individuals had Type 1.5 diabetes. Several other studies have shown similar results as well as the presence of antibodies, especially those against glutamic acid decarboxylase (GAD), characteristic of Type 1 in this group of people diagnosed with Type 2.
Causes & Development
Type 1.5 diabetes has virtually the same underlying cause as type 1. The difference is that type 1.5 happens in people older than 25, whereas type 1 happens in childhood, the teen years and young adulthood. People as old as 80 have been diagnosed with type 1.5.
Diagnosis & Tests
A misdiagnosis is easy to make when the patient is older and responds well at first to treatment with oral medications. If someone does not clearly fit the model for Type 1 diabetes, they may be mistakenly placed on oral agents even though limited capacity for insulin production remains. The immune system's slower and more selective attack on the beta cells allows these cells to function to a high degree for a few years. On average, insulin is required in half of those with Type 1.5 diabetes within four years of diagnosis, compared to over ten years in those with true Type 2. [Endocrine Practice, 7(5), Sept/Oct 2001, pp.339-45]
Treatment & Prevention
Since insulin resistance is minimal or non-existent, medications designed to reduce insulin resistance such as Avandia and Actos are not effective. Other medications that stimulate the pancreas to produce insulin, slow digestion of carbohydrates, or reduce excess glucose production by the liver are often effective in controlling the blood sugar for a few years.
Knowing your diabetes type can give you a better understanding of the changes that may occur as you age and the disease progresses. For example, if you have had insulin-resistant diabetes for several years that has become harder to control on a sulfonylurea medication and your C-peptide level (a lab test that measures insulin production) is now low, the addition of insulin will be needed. However, if your control of the diabetes is poor and your C-peptide is normal, adding another oral agent and paying closer attention to your food and exercise choices may be all that is required.
As insulin production falls, insulin becomes necessary to maintain control of the disease. One indication that people have Type 1.5 rather than Type 2 is their appearance, which is more likely though not always slender and physically fit. They often do not have other signs of Type 2 diabetes, such as the Syndrome X cluster of high TGs, low HDL or high blood pressure. Fortunately, in these early stages, diabetes treatment is not significantly different for slow-onset Type 1.5 patients than for truly insulin-resistant Type 2 patients. The only exception is that drugs designed to increase insulin sensitivity like the glitazones do not work because insulin sensitivity is normal.
Prognosis
One major benefit for patients with Type 1.5 diabetes is that when their blood sugars are controlled they usually do not have the high risk for heart problems more often found with the high cholesterol and blood pressure seen in true Type 2 diabetes.
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Conditions that suggest Diabetes Type 1.5: | | | | | Autoimmune |  Diabetes Type I |
Circulation |
 Coronary Disease / Heart Attack | It is not clear yet if people with type 1.5 have the same high risk for cardiovascular problems as individuals with type 2. |
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Organ Health |
 Diabetes Type II| | Approximately 15% to 20% of people diagnosed as "Type 2" in fact have Type 1.5. They are often diagnosed as Type 2 because they are older and will initially respond to diabetes medications because they have adequate insulin production. The initial treatment may involve diet change, exercise and standard Type 2 medications. |
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Recommendations and treatments for Diabetes Type 1.5: | | | | | Hormone |  Insulin Therapy| | On average, insulin is required in half of those with Type 1.5 diabetes within four years of diagnosis, compared to over ten years in those with true Type 2. |
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KEY | | Weak or unproven link | | | Strong or generally accepted link | | | Proven definite or direct link | | | Highly recommended |
GLOSSARY
Antibody (Antibodies)
A type of serum protein (globulin) synthesized by white blood cells of the lymphoid type in response to an antigenic (foreign substance) stimulus. Antibodies are complex substances formed to neutralize or destroy these antigens in the blood. Antibody activity normally fights infection but can be damaging in allergies and a group of diseases that are called autoimmune diseases.
Autoimmune Disease (Autoimmune, Autoimmunity)
One of a large group of diseases in which the immune system turns against the body's own cells, tissues and organs, leading to chronic and often deadly conditions. Examples include multiple sclerosis, rheumatoid arthritis, systemic lupus, Bright's disease and diabetes.
Carbohydrates (Carbohydrate)
The sugars and starches in food. Sugars are called simple carbohydrates and found in such foods as fruit and table sugar. Complex carbohydrates are composed of large numbers of sugar molecules joined together, and are found in grains, legumes, and vegetables like potatoes, squash, and corn.
Cardiovascular
Pertaining to the heart and blood vessels.
Cholesterol
A waxy, fat-like substance manufactured in the liver and found in all tissues, it facilitates the transport and absorption of fatty acids. In foods, only animal products contain cholesterol. An excess of cholesterol in the bloodstream can contribute to the development of atherosclerosis.
Diabetes Mellitus (Diabetes, Diabetic, Diabetics)
A disease with increased blood glucose levels due to lack or ineffectiveness of insulin. Diabetes is found in two forms; insulin-dependent diabetes (juvenile-onset) and non-insulin-dependent (adult-onset). Symptoms include increased thirst; increased urination; weight loss in spite of increased appetite; fatigue; nausea; vomiting; frequent infections including bladder, vaginal, and skin; blurred vision; impotence in men; bad breath; cessation of menses; diminished skin fullness. Other symptoms include bleeding gums; ear noise/buzzing; diarrhea; depression; confusion.
Glucose
A sugar that is the simplest form of carbohydrate. It is commonly referred to as blood sugar. The body breaks down carbohydrates in foods into glucose, which serves as the primary fuel for the muscles and the brain.
Glutamic Acid
Involved in the synthesis of DNA, glutathione and some amino acids. Helps remove excess ammonia from the body. Interconverted by the body into glutamic acid and gamma-amino-butyric acid (GABA).
High-Density Lipoprotein (HDL)
Also known as "good" cholesterol, HDLs are large, dense, protein-fat particles that circulate in the blood picking up already used and unused cholesterol and taking them back to the liver as part of a recycling process. Higher levels of HDLs are associated with a lower risk of cardiovascular disease because the cholesterol is cleared more readily from the blood.
Immune System (Immune Response, Immunity)
A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation. The process may involve acquired immunity (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing).
Insulin
A hormone secreted by the pancreas in response to elevated blood glucose levels. Insulin stimulates the liver, muscles, and fat cells to remove glucose from the blood for use or storage.
Liver (Hepatic)
The largest and one of the most complex organs of the body, the liver is responsible for much of the metabolism of fats, proteins and carbohydrates. It is the site of much of the body's detoxification. It is connected very closely with digestion and the regulation of blood sugar, among many other functions. Found behind the ribs on the right side of the abdomen, it has many important functions such as removing harmful material from the blood, making enzymes and bile that help digest food, and converting food into substances needed for life and growth. Hepatic: Pertaining to the liver.
Pancreas (Pancreatic)
Opposite the liver and behind the stomach, the pancreas has two main functions - to manufacture various enzymes for digestion, and to release hormones to help control the body's use of carbohydrates. It releases insulin to help each cell absorb glucose to burn as energy. In this way, insulin controls the amount of sugar (glucose) in the blood. Proper pancreatic function is very important: too much, too little, or no insulin production can be life-threatening. Some of the chemicals released by the pancreas are not hormones, but stimulate other glands to make hormones. Once again, balance is necessary. Nutritional requirements for the pancreas are many. Research indicates that chromium vitamins C, E, B-complex, calcium, magnesium and potassium are especially important.
Syndrome
A medical condition characterized by a collection of related symptoms (what the patient feels) and signs (what a doctor can observe or measure).
Last updated: Apr 13, 2008
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