Diabetes mellitus is a general term for heterogeneous disturbances in the metabolism of protein, carbohydrate,s and fat. It is characterized by abnormalities in the secretion of insulin, the sensitivity of insulin receptors to insulin or both.
Insulin is a hormone that is made in pancreas. It facilitates transport of glucose from blood to the cells (glucose uptake) to be used as energy. Thus it maintains blood glucose/sugar level within normal limits. When the blood glucose level increases, insulin secretion starts. Its secretion stops when the blood glucose level falls. Insulin also promotes protein synthesis in muscles.
Types of Diabetes Mellitus:
There are the following main types of diabetes mellitus.
1.Type 1 Diabetes Mellitus:
An autoimmune reaction is responsible for type 1 DM. In an autoimmune reaction the body attacks itself and as a result body stops making insulin.
It is also called insulin-dependent diabetes because the patient with Type 1 diabetes needs to take insulin. Approximately 5-10% of diabetic patients have type 1 diabetes. It generally develops in children and young adults (but it can affect any age group). Its Symptoms often develop quickly.
Due to disturbance in immune system there is initiation of circulating autoantibodies (circulating islet cell antibodies) to various beta cell antigens. These autoantibodies are involved in the destruction of insulin secreting beta cells of the islets of langerhans of pancreas. As beta-cell mass declines, insulin secretion decreases. Hyperglycemia (high blood glucose/sugar) develops after destruction of 80-90% of the beta cells. Circulating islet cell antibodies are responsible for approximately 85% of type 1 DM cases and the majority of patients also have detectable anti-insulin antibodies before receiving insulin therapy.
Autoimmune destruction of the beta cells of the pancreas involves both genetic predisposition and an environmental component/ extragenetic factors that include viruses (eg, enterovirus, rubella,mumps, and coxsackievirus B4), toxic chemicals, cytotoxins and use of cow milk in infants.
The risk for type 1 diabetes is increased in patients with other autoimmune diseases, such as Graves disease, autoimmune thyroiditis and Addison disease.
2. Type 2 Diabetes Mellitus:
It is also called insulin-resistant diabetes. In this type of DM there is decreased sensitivity of insulin receptor to insulin. Thus the body does not use insulin well and can’t keep blood sugar at normal levels. About 90-95% of DM patients have type 2 diabetes. It generally develops in middle aged and older people. It develops over many years.
The factor that is responsible for insulin resistance is diabetogenic lifestyle (i.e, excessive caloric intake, inadequate caloric expenditure/ exercise, obesity)
The risk for type 2 DM increases in the following cases:
- Age greater than 45 years (although frequency of type 2 DM is also increasing in young adults).
- Over weight.
- Family history of type 2 diabetes in a first-degree relative (i.e, parent or sibling).
- People having history of gestational diabetes mellitus or of delivering a baby with a birth weight of over 9 lb.
- Hypertension (high blood pressure) (>140/90 mm Hg) or dyslipidemia (HDL cholesterol level < 40 mg/dL or triglyceride level >150 mg/dL).
- Polycystic ovarian syndrome (which results in insulin resistance).
- Some medications (e.g Thiazide diuretics, beta blockers, glucocorticoids).
3. Type 3 Gestational Diabetes:
This type of DM develops in some women during their pregnancy who don’t have diabetes previously. It usually goes away after pregnancy. However, the women who have gestational diabetes is at higher risk of developing type 2 diabetes later on in life.
Short-term complications include Hypoglycemia (low blood glucose/sugar).
Long-term complications of diabetes develop gradually. The risk of complications is increased if you have diabetes for a long period of time with less controlled blood sugar. Long term complications include:
- Heart disease (diabetic cardiomyopathy) and stroke, are caused by damage to blood vessels and the nerves that control the heart and blood vessels.
- Kidney disease (diabetic nephropathy), occurs due to damage to the blood vessels in the kidneys. Diabetic patients may develop high blood pressure that can also cause damage to the kidneys.
- Eye disease (diabetic retinopathy), caused due to changes in fluid levels, swelling in the tissues, and damage to the blood vessels in the eyes. It can lead to blindness, cataracts, and glaucoma.
- Nerve problems (diabetic neuropathy), cause numbing and tingling that starts at the toes or fingers and then spreads.
- Foot problems, are caused by damage to the nerves, poor blood flow, and poor healing of cuts and sores.
- Gum disease and other dental problems may occur because a high amount of blood sugar in the saliva helps harmful bacteria grow in the mouth.
- Skin conditions
Symptoms of both type 1 and type 2 DM are similar but they vary in intensity. Those with type 1 DM are more severe and fast in onset.
Common symptoms include:
- Excessive urine production
- Increase thirst
- Excessive eating or appetite
- Fatigue, due to inability to utilize glucose
- Weight loss, because of the breakdown of body protein and fat as an alternative energy source to glucose.
- Blurred vision, caused by a change in lens refraction.
- Patients may also experience higher infection rate, especially candiada and urinary tract infection due to increased urinary glucose levels.
This test is also called hemoglobin A1C, HbA1C, glycated hemoglobin, and glycosylated hemoglobin test. The A1C test gives information about average blood sugar level for the past two to three months. This test measures the percentage of blood sugar/glucose attached to hemoglobin (protein in red blood cells that carry oxygen). The higher your blood sugar levels, the more hemoglobin is attached with sugar.
AC1 values and their interpretations:
- Less than 5.7% = Normal
- 5.7% to 6.4% = Pre-diabetes
- 6.5% or higher = Diabetes
The person is diabetic if A1C value is equal to or greater than 6.5%.
Fasting Plasma Glucose (FPG):
This test checks blood sugar levels during fasting state. The person have to stop eating and drinking (except water) for at least 8 hours before the test. This test is usually performed before breakfast.
FPG values and their interpretations:
1. Less than 100 mg/dl = Normal
2. 100 mg/dl to 125 mg/dl = Pre-diabetes
3. 126 mg/dl = Diabetes
The person is diabetic if fasting blood sugar is equal to or greater than 126mg/dl.
3. Oral Glucose Tolerance Test (OGTT):
For this test the person stops eating and drinking (except water) for atleast 8 hours before the test. The OGTT is a two-hour test that measure blood sugar levels before and two hours after drinking a liquid containing glucose. It tells the doctor how your body processes sugar.
OGTT values and their interpretations:
- Less than 140 mg/dl = Normal
- 140 mg/dl to 199 mg/dl = Pre-diabetes
- 200 mg/dl or higher = Diabetes
The person is diabetic if OGTT is equal to or greater than 200 mg/dl.
Random (Casual) Plasma Glucose (RPG):
In this test there is measurement of blood sugar levels at any time of the day when the person is suffering from severe diabetes symptoms and health care professionals do not wait until he has fasted.
The person is diabetic if RPG is equal to or greater than 200 mg/dl.
Diagnosis of diabetes is confirmed when classical symptoms of hyperglycemia exist along with random plasma glucose concentration of equal to or greater than 200 mg/dl or a fasting plasma glucose concentration of equal to or greater than 126 mg/dl.
The goals for patients of diabetes mellitus are to eliminate symptoms of hyperglycemia, reduce the onset and progression of complications and improve quality of life. Management of diabetes requires day-to-day care. It includes:
- Reqular monitoring of blood glucose levels.
- Dietary/nutritional management
- Maintaining physical activity
- Keeping weight and stress under control
- Monitoring drug therapy
- CDC: Centers for Disease Control and Prevention
- Cleveland Clinic
- American Diabetes Association
- UCFS Health