Classifications of Diabetes



Classifications of Diabetes

Definition of Diabetes Mellitus - Diabetes Mellitus is a chronic metabolic disease characterized by hyperglycemia. Hyperglycemia results from the body's inability to secrete insulin, the inability to use insulin or both.

Pathogenic processes involved in the development of diabetes mellitus range from autoimmune destruction of the beta cells in the pancreas to abnormalities that result in insulin resistance. The autoimmune response can result in total beta cell dysfunction (type 1) or partial beta cell destruction (type 2). The severity of the metabolic abnormality can progress, regress, or stay the same.

The chronic hyperglycemia of diabetes is associated with vessel damage, which results in damage to or failure of various vital organs such as the eyes, kidneys, nerves and the heart. People with Type 2 Diabetes are at a significantly higher risk for developing coronary heart disease, peripheral vascular disease and stroke. They also have a greater likelihood of having hypertension, dyslipidemia and obesity.

Diabetes is one of the most costly and burdensome chronic diseases of our time and is a condition that is increasing in epidemic proportions in the US and throughout the world. The complications resulting from diabetes are a significant cause of morbidity and mortality.

Diabetes Statistics – In 2005, approximately 23.6 million children and adults (8 % of the US population) had diabetes. It is estimated another 5.7 million people have diabetes but are undiagnosed and 57 million have Pre-diabetes. There was 1.6 million new cases of diabetes were diagnosed in people 20 years and older in 2007.

Data is now showing that 186,000 or 22 % of people in the age group 20 and under have diabetes as well. About one in every 400 to 600 children and adolescents have Type 1 Diabetes. In the age group 12-19, two million adolescents or 1 in 6 are overweight and have pre-diabetes. Clinically-based reports and regional studies suggest that type 2 diabetes, although still rare, is being diagnosed more frequently in children and adolescents. In the age group 20 and older 23.5 million or 10.7% of all people have diabetes and 12.2 million or 23.1 % of all people in the 60 and older age range have diabetes. In men 12 million or 11.2 % age 20 and older have diabetes although nearly one third of them do not know it. In women age 20 and over 11.5 million or 10.2 % have diabetes and nearly one quarter of them do not know it.

Diabetes is more prevalent in Native Americans, Hispanics/Latinos Americans, Native Hawaiians, and African-Americans and some Asian Americans and other Pacific Islanders. The increasing number of ethnic minorities in the United States may contribute to the increasing prevalence of type 2 diabetes. The lowering of the diagnostic criteria by the American Diabetes Association for the diagnosis of diabetes from a fasting glucose of 140mg/dl to 126 mg/dl has also contributed to the higher prevalence of diabetes.

Classifications of Diabetes –‘Diabetes Mellitus can be divided into three main clinical categories:

1. Diabetes Mellitus (with two clinical sub-classes)

• Type 1 Diabetes Mellitus

• Type 2 Diabetes Mellitus - (Impairment of insulin secretion and insulin action frequently coexists in the same patient).

2. Gestational Diabetes Mellitus (GDM)

3. Impaired Glucose Tolerance (IGT)

Type 1 Diabetes Mellitus – This form of diabetes accounts for 5-10% of those with diabetes, and was previously referred to as insulin dependent diabetes, Type 1 Diabetes or Juvenile-Onset Diabetes. This form of diabetes usually strikes children and young adults, although disease onset can occur at any age. Type 1 Diabetes results from autoimmune destruction of the pancreatic beta cells. The rate of beta cell destruction can be variable, being rapid in some individuals (mainly infants and children) and slow in others (mainly adults).

Risk factors for Type 1 Diabetes may be autoimmune, genetic, or environmental. Although these patients are rarely obese when they present with Type 1 Diabetes, the presence of obesity is not incompatible with the diagnosis. Upon diagnosis, a patient may present with ketoacidosis as the first manifestation of the disease. Others may have modest fasting hyperglycemia that can rapidly change to severe hyperglycemia and or ketoacidosis in the presence of infection or other stress. To survive people with Type 1 Diabetes must have insulin delivered by injection or insulin pump. There is no known way to prevent Type 1 Diabetes.

Type 2 Diabetes Mellitus – This form of diabetes accounts for 90-95 % of those with diabetes and was previously referred to as non-insulin dependent diabetes, Type II or adult-onset diabetes. This form of diabetes encompasses individuals who have insulin resistance and relative insulin deficiency rather then absolute insulin deficiency. It usually begins with insulin resistance, a disorder in which the cells do not use insulin properly. As the need for insulin arises the pancreas gradually loses its ability to produce insulin.

Type 2 Diabetes is associated with older age, obesity, family history of diabetes, history of gestational diabetes, impaired glucose metabolism, physical inactivity, and race/ethnicity. However clinically based reports and regional studies suggest that Type 2 Diabetes in children and adolescents although still rare, is being diagnosed more frequently, particularly in the high-risk ethnic groups. In most cases, at least initially, and often throughout their lifetime, these individuals do no need insulin treatment to survive.

Most people with Type 2 Diabetes are obese, and obesity itself causes some degree of insulin resistance. Those who are not obese by traditional weight criteria may have an increased percentage of body fat distributed predominantly in the abdominal region.

Ketoacidosis rarely occurs spontaneously in Type 2 Diabetes. Type 2 diabetes frequently goes undiagnosed for many years because the hyperglycemia develops gradually and at the earlier stages is often not severe enough for the patient to notice the classic symptoms. People with type 2 may have insulin levels that appear normal or elevated. The higher blood glucose levels in these people result in even higher insulin levels if their beta cell function was normal. Thus, insulin secretion is defective in these patients and insufficient to compensate for insulin resistance. Insulin resistance may improve with weight reduction and / or pharmacological treatment of hyperglycemia but is seldom returned to normal.

The risk factors for developing Type 2 Diabetes increase with age, obesity, and lack of physical activity. type 2 occurs more frequently in women with prior history of Gestational Diabetes Mellitus, in individuals with hypertension or dyslipidemia and is often associated with a strong genetic predisposition.

Gestational Diabetes (GDM)– GDM is a form of glucose intolerance with onset or first recognition during pregnancy. Treatment is required during pregnancy to normalize maternal glucose levels and avoid complications. Treatment is Medical Nutrition Therapy (MNT) and in some cases insulin therapy. GDM complicates 4 % of all pregnancies in the US. Risk assessment for GDM should be untaken at the first prenatal visit. Women with clinical characteristics consistent with a high risk of GDM (marked obesity, personal history of GDM, glycosuria, or a strong family history of diabetes) should undergo testing. If they are found to have GDM at that initial screening they should be retested between 24-28 weeks of gestation.

Pre- Diabetes, Impaired Glucose Tolerance (IGT) and Impaired Fasting Glucose (IFG) are recognized in someone whose glucose levels are high but not high enough to be diagnosed with diabetes. This group is defined as having a fasting plasma glucose (FPG) greater then 100 mg/dl. Patients with IFG or IGT are now referred to as having pre-diabetes, indicating they are relatively high risk for developing diabetes and cardiovascular disease. MNT aimed at producing 5-10 % loss of body weight as well as exercises has been demonstrated to prevent or delay the development of diabetes in people with IGT or IGF.

Criteria for Diagnosis of Diabetes Mellitus– Criteria for Diabetes Mellitus include any one or more of the following:

1. Symptoms of diabetes plus casual plasma glucose of greater then 200 mg/dl (11.0 mmol/l). Casual is defined as any time of the day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia and unexpected weight loss.

2. Fasting plasma glucose greater then 126 mg/dl(7.0 mmol/l). Fasting is defined as no caloric intake for at least eight hours.

3. Two-hour post-load oral glucose tolerance test (OGTT) greater then 200mg/dl during an OGTT. The OGTT test should be performed using a glucose load of 75 grams anhydrous glucose dissolved in water.

Criteria for Diagnosis of Gestational Diabetes Mellitus;

OGGT

100gram glucose load

Fasting 95mg/dl 5.3 mmol/l

1 hour 180mg/dl 10.0 mmol/l

2 hour 155 mg/dl 8.6 mmol/l

3 hour 140mg/dl 7.8 mmol/l

75 gram glucose load

Fasting 95 mg/dl 5.3 mmol/l

1 hour 180mg/dl 10.0 mmol/l

2 hour 155mg/dl 8.6 mmol/l

Two or more of the venous plasma concentrations must be met or exceeded for a positive diagnosis of GDM. The test should be done in the morning after an overnight fast of 8-14 hours and after three days of unrestricted diet (greater then 150 grams of carbohydrates per day). Patient should remain seated and not smoke during test.

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