Type 1 Diabetes: An Overview

Type 1 diabetes is a chronic autoimmune disease that affects the control of blood sugar. Type 1 diabetes (T1D) used to be called “Insulin-Dependent Diabetes Mellitus” (IDDM) and “Juvenile-Onset Diabetes” because it is most commonly found in children and young adults. T1D is a treatable condition, though it does require commitment to keeping track of your blood sugar levels, watching what you eat and staying up-to-date on your insulin and medication schedules. With that commitment, most people can look forward to full and active lives.

Causes of T1D

The causes of T1D are really unknown, but it often seems related to a viral infection. T1D is an autoimmune disease, and this means that your immune system has gotten “confused” in some way, sometimes after that viral infection “triggers” a confused response in genetically susceptible people. The viral infection may trigger the immune system and in those with a genetic susceptibility; the end result may be that the immune system begins to attack the beta-cells of the pancreas where insulin is made.¹

The immune system’s job in the body is to protect “self” from anything that the immune system senses is “non-self”. There are two main “arms” of the immune system—the cellular immune system and the humoral immune system. In T1D, the signals for self and non-self can get crossed and the immune system responds by destroying the beta-cells of the pancreas—these are the cells that normally produce insulin.

• The cellular immune system uses various types of T-lymphocytes (white blood cells) or T cells and other immune cells to destroy anything that is perceived or sensed as non-self. Cellular immunity is involved in the immune system’s response to viruses, bacteria and cancer cells. Cellular immunity also plays a role in transplant rejection.
• The humoral immune system involves another type of lymphocyte, the B-lymphocyte or B-cell. B cells produce a specific type of protein, the antibodies which attach to anything seen as non-self. These antibodies can be detected in the blood and are also involved in the immune system’s response to viruses and bacteria and sometimes cancer cells.
• In most people with T1D both arms of the immune system play a role in the destruction of the insulin-secreting beta cells. For example, about 85% of people with T1D have antibodies to an enzyme, glutamic acid decarboxylase (GAD). GAD is an enzyme found within the beta cells of the pancreas.
• It is important to know that the presence of one autoimmune disorder increases the risk of other autoimmune disorders such as rheumatoid arthritis, thyroid disease (eg. Hashimoto’s thyroiditis, Graves’ disease), Celiac disease and others.² You or your child should be periodically screened for these types of disorders.

Genetic and Environmental Susceptibility

T1D involves the interplay of a number of different genes—the genes that are most associated with T1D are in the HLA-DR and DQ families (haplotypes).¹ There are other genes that are associated with T1D—these include the genes associated with the activation of T cells (CTLA4, PTPN22, IL2RA) and other genes. Having one of more of these genes increases the risk of T1D but there seems to be an association of T1D with environmental factors as well.

As mentioned above, T1D can sometimes be triggered by a viral infection—these viral infections include infection with enterovirus (causing usually mild respiratory and flu-like symptoms), the mumps, rubella and coxsackie B4 viruses. Other potential environmental factors include exposure to toxic chemicals, cow’s milk and low Vitamin D levels.

Diagnosis

T1D, still often referred to as Juvenile Onset Diabetes, is commonly diagnosed in children, but about 50% of diagnoses occur in people in their 20s. When T1D is diagnosed in people in their 20s, it is known as latent autoimmune diabetes of the adult (LADA) or Type 1.5 Diabetes.³

The symptoms of T1D classically are:

• Increased thirst
• Increased frequency of urination
• Increased appetite
• An unexplained weight loss

In very young children, symptoms may include bed-wetting. Other symptoms can include fatigue, irritability or unusual behavior, blurry vision, nausea and abdominal discomfort. Young girls may have genital yeast infections while babies may have a severe diaper rash caused by (usually) candida, a type of yeast.

These symptoms may occur suddenly and may occur along with the symptoms of a potentially severe complication of diabetes, diabetic ketoacidosis (DKA). The symptoms to watch for in DKA include:⁴

• A sudden increase in thirst and urination
• Nausea and vomiting
• Abdominal pain
• Sudden fatigue
• Shortness of breath or difficulty breathing
• A “fruity” scented breath
• Confusion

In addition, especially because these symptoms are often not very clear early on, the diagnosis depends on lab values. The criteria for diagnostic lab values include:⁵

• A fasting plasma sugar (glucose) level of greater than or equal to 126 mg/dL (7.0 mmol/L), OR
• A 2-hour plasma sugar (glucose) level of greater than or equal to 200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test (OGTT), OR
• A random plasma sugar (glucose) level of greater than or equal to 200 mg/dL (11.1 mmol/L) in anyone with symptoms of high blood sugar
• A1c levels may be used as well for diagnosis and maintenance —these can be based on the age of the person with T1D.

Complications of T1D

Uncontrolled or poorly controlled T1D has the potential of causing some severe complications because it can affect the heart, the blood vessels, the nervous system, the kidneys, the bones and the eyes. These complications can occur even in the very young, but more commonly will affect someone later in the course of the diabetes, as an older adult.

Treatment of T1D

Individuals with T1D require life-long insulin replacement therapy and close monitoring of blood sugar levels. In young children, this often requires initial hospitalization and a great deal of family involvement. According to the most recent guidelines, A1c level goals should be less than 7.5%, though this goal can change for different individuals.⁶ At least at first, most patients with T1D require 2 or more injections of daily insulin to control blood sugar levels. One of the most important goals of treatment in any form of diabetes is to maintain steady glucose levels. This is often referred to a maintaining “tight glycemic control”. Tight glycemic control has been shown to limit and reduce the complications of diabetes.

Anyone with T1D will need to keep track of their blood sugar levels—young children can eventually learn to monitor their own. Usually, the blood sugar levels are checked daily before meals, after meals (1-2 hours after eating) and at bedtime. Insulin doses can be adjusted based on those blood sugar levels. Especially for young children, this requires parental involvement and a good deal of education, training and support for the whole family. There are a number of different forms of insulin available—these forms of insulin can be rapid acting (within 5-10 minutes), short acting (within 45-75 minutes), intermediate acting, long-acting and ultra-long acting. Often, a combination of these insulins can be prescribed, depending on the needs of the individual. Insulin “pen injectors” can be helpful, especially for young children who may have difficulties with regular needle injections.⁷

Some of the different insulins and delivery methods available include:

• Rapid acting insulins include Humalog and Novolog
• Short acting insulins include Humulin and Novolin
• Long acting insulins include Lantus and Levemir
• Intermediate acting insulins include Humulin N and Novolin N
• Insulin pens
• Insulin pumps

Insulin is usually the only medical treatment that is required, but dietary, nutritional and exercise habits are very important as well.

General Dietary and Exercise Recommendations

The following are the generally accepted dietary recommendations:⁸

• Minimize refined (processed) carbohydrates to less than 10% of the total carbohydrates daily. Complex carbohydrates (from whole, unprocessed foods and fruit) should be about 50-55% of the daily calorie intake
• Healthy fats (from fish, poultry, lean meats, eggs, dairy and fresh vegetables) should be about 30-35% of the daily calorie intake
• Lean, high quality protein should be about 10-15% of the daily calorie intake.
• Meals and snacks should be as regular as possible

Everyone with T1D should exercise regularly. Be aware that physical activity (as well as infections, other illnesses and any form of stress) can alter blood sugar levels. Blood sugar levels should be closely checked after physical activity as well as during any periods of illness, trauma or other physical, mental or emotional stress.⁹

Coping and Support

A diagnosis of T1D can be emotionally difficult for anyone, but it can be difficult for families as well. There are informational and emotional support groups available to help individuals and families cope, particularly as many children with T1D also experience eating disorders, depression and anxiety.² Make certain your child wears a medical ID bracelet and the school is aware of their condition. Stay in touch with everyone involved in the care of your child and make certain that your and your child’s questions and concerns are answered. Research is ongoing, but today, anyone with a T1D diagnosis can look forward to a healthy and active life if insulin therapy, tight glycemic controls, dietary and exercise recommendations are maintained.