Diabetes
Type 1 and Type 2 diabetes are as different as they are similar. While the pancreas of a Type 1 patient cannot make insulin, Type 2 patients have healthy beta cells and normal insulin production, but they develop insulin resistance over time. |
Paean to the pancreas
Type 1 diabetes
by Bess Andrews
Can you draw a picture of the pancreas? Can you find it on a map of the human body? Unlike its better known organ relatives, the brain, heart and lungs, the pancreas keeps a pretty low profile. Tucked behind and beneath the stomach and next door to the liver, the pancreas is roughly the shape and size of a banana. Its anonymity aside, the pancreas is an amazing organ—deserving celebrity in its own right for its starring role in producing insulin, an unheralded function that most of us take for granted.
As carbohydrates contained in food are digested, they are absorbed into the bloodstream through the walls of the intestine and ultimately are converted into glucose (or blood sugar). Insulin is responsible for moving this glucose from the blood stream into cells, where it is used for energy. When this system goes awry, blood sugar disorders such as Type 1 and Type 2 diabetes, which are characterized by abnormally high glucose levels, ensue.
Type 1, formerly referred to as juvenile diabetes, is actually an autoimmune disease that affects both children and adults. The pancreas is filled with over one million clusters of cells, known as islets of Langerhans, which contain the beta cells where insulin is made. For reasons that researchers are only just beginning to fathom, the immune system in Type 1 diabetics turns against these islets and progressively destroys the beta cells within, leading to a deficiency of insulin that, if left untreated, can be life threatening. This results in a state where there is plenty of glucose in the blood, but without the assistance of insulin, the body cannot use it. Because the immune system of diabetics destroys insulin-producing beta cells, children and adults with this form of diabetes require daily insulin early in their disease to allow the body to use the glucose.
In a non-diabetic, the beta cells of the marvelous and complex pancreas measure and monitor blood glucose levels 24 hours a day, and secrete more or less insulin as needed. When people eat a meal high in carbohydrates (which have a high "glycemic index," meaning they are rapidly absorbed and converted to glucose), they get a burst of insulin to move the glucose from the blood stream to the cells, where it can be used as energy or stored in the liver or muscles for later use. Between meals, the pancreas secretes just the necessary amount of background insulin to keep the healthy body functioning well. In non-diabetics, this finely-tuned system always keeps blood glucose levels within the narrow range of normal.
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Studies over the last two decades have shown that by keeping glucose levels as close to normal as possible, diabetics can dramatically postpone or prevent many of the long-term complications of diabetes, such as blindness, circulatory problems, heart attack, stroke and kidney failure. "Our goal at Children's is to do whatever we can to restore blood sugar levels as near to normal as possible," says Joseph Wolfsdorf, MD, director of the Diabetes Program. "This provides a better quality of life, increases life expectancy, delays the onset of complications and allows patients to take advantage of new advances as they come along."
But tight glucose regulation is a difficult goal and places a huge burden on patients, families and caregivers by requiring precise planning and timing to maintain a balance between food intake, insulin doses and exercise. Today, parents and patients are faced with performing four to eight blood tests a day, calculating expected carbohydrate intake and choosing the appropriate dose of short-acting or long-acting insulin, depending on their child's planned activity level and meal schedule. They must become medical experts in the disease so they can cope with everything from a missed snack to low blood sugar, which untreated may cause mental confusion, impaired judgment or seizures. To attain this level of parental knowledge and confidence, Children's staff spend hundreds of hours educating, counseling and providing phone consultations and advice to each patient family. This education must then be extended to any other adult who cares for the child.
Kelley Maher was 10 years old when she was diagnosed with Type 1 diabetes. Always a healthy, athletic child, she developed an increased thirst and need to urinate in the fall of 2000. Her mother Michelle was suspicious of these symptoms but wrote them off to the heat and Kelley's high activity level. But when Michelle noticed that Kelley was losing weight, she immediately took Kelley to her pediatrician, who tested her urine for glucose and ketones. Ketones are produced when the body burns fat because it cannot access glucose for fuel. The presence of very elevated blood sugar with a high level of ketones indicates that the body's metabolism is dangerously out of kilter and there is risk of life-threatening ketoacidosis. Kelley's pediatrician arranged an emergency admission to Children's.
The Maher's diabetes education began their first night at Children's. "When I first heard Kelley's diagnosis," says her father Kevin, "I immediately called a physician friend who told me there was a lot of great research going on in the field and a cure was in sight. So I brought this up to Dr. [Yanira] Pagan, the endocrinology fellow, and she gave it to me straight: 'No, we are not close to a cure,' she said. 'Kelley can lead a normal life, but this is a very serious illness and you have to begin dealing with it now, because it is going to change your whole life.'" Kevin looked on closely as the nurses gave Kelley her insulin injections that night; he was expected to do it himself the next morning.
"We were bombarded with so much information. I was really overwhelmed," remembers Michelle. "But the diabetes nurse educators spent so much time with us; it was really comforting and confidence-building." When Kelley came home two days later, it felt like the day Kevin and Michelle first brought her home as a newborn. "The responsibility was enormous. Diabetes is a very serious illness, and I was her front-line caregiver," says Michelle.
In the past decade, patient-controlled continuous infusion insulin pumps became available for use in children and adolescents. The pager-sized pump delivers insulin in two ways: a patient programs in a low-level background rate of insulin to be delivered throughout the day and night, just the way a healthy pancreas does. This keeps glucose levels in control between meals and during the night. The second method allows a patient to time a burst of insulin to be delivered shortly before eating to cover the carbohydrates in the meal. The insulin is delivered just under the skin with a small needle and tubing connected to the pump, but it is not for everybody. "It takes a motivated patient and family to learn to use the pump safely and effectively," says Wolfsdorf. "In addition to the upfront training and education, using a pump requires constant vigilance on the part of the patients and families, and they have to check blood sugar levels up to ten times a day."
At the Mahers' initiative, Kelley started on an insulin pump in June 2001. "Kelley adapted beautifully," says Kevin. "She's always been a real gadget queen, programming the car radio and VCR, so she learned how to work the pump very easily." Kelley loves the pump because it allows her to manage her glucose level very tightly while giving her back some of the spontaneity of childhood. "Now, I can eat when I'm hungry and not have to wait for snack time, or I can sleep in on the mornings I don't have school or a sporting event, rather than waking up just to get a shot of insulin," she says. "And I can disconnect the pump for limited periods when I'm going to exercise."
The pump is not the final answer, however, and Children's physicians and researchers are still looking for better treatments for children with Type 1 diabetes. "Until the day a pump can deliver insulin in a physiologic way—when it can read blood sugar levels and react with the appropriate dose—the brain will still be the organ behind the decision-making," says Norman Spack, MD, Kelley's endocrinologist and clinical director of the Division of Endocrinology. "To be able to truly control blood sugar levels within that narrow range we call normal—whether fasting or fed, ill or well—you need to have functioning beta cells, which are smarter than any pump." says Spack.
In the meantime, Kelley's diabetes and her pump have not slowed her down a bit’Äîshe plays soccer, basketball, skis and is on a swim team. "When I was in the hospital, they told me that diabetes would become a part of my life," she says. "It was hard to believe then, but it's true. Now taking insulin is just another thing I do every day, like brushing my teeth."
Fast food, slow lifestyle
Type 2 diabetes
While Type 1 diabetes is largely genetic in origin, Type 2 stems from a genetic predisposition as well as controllable factors such as poor eating habits and a sedentary lifestyle. Early on, the course of Type 2 diabetes can be reversed through diet and exercise, enabling patients to return to normal glucose tolerance, thus avoiding diabetes.
In Children's Optimum Weight for Life (OWL) Clinic, David Ludwig, MD, PhD, director of the program, studies the relationship of diet, obesity and Type 2 diabetes, and treats overweight and obese children. Obesity in the United States is epidemic, affecting approximately 50 percent of adults and 25 percent of children. Concurrent with the increase in American obesity is a 10-fold increase in the incidence of Type 2 diabetes over the last two decades, and the connection between the two seems unequivocal. Published studies show that the mean body mass index (or BMI, a calculation based on height and weight used to determine if someone is under- or overweight) of children with Type 2 diabetes is typically above the 95th percentile for their age.
In a series of published studies over the last four years, Ludwig has demonstrated that high glycemic index diets (high in simple and refined carbohydrates like those in sugar cereals and fast foods) increase insulin levels and contribute to excessive weight gain through two mechanisms. High insulin levels, he believes, program the body to store calories from meals rather than use them. Then, when the blood glucose level eventually plummets, it triggers hunger and overeating all over again. Ludwig has demonstrated that low glycemic index diets, which involve intake of complex carbohydrates (found in vegetables, whole wheat and legumes, for example) and fiber, achieve lower insulin levels and reduce weight. In so doing, he has challenged the fast food, soft drink and cereal manufacturers who market these highly refined, high-calorie, low-nutrition products to kids.
Founded in 1997, the OWL Program's patient volume has doubled in the last three years to 2,000 visits per year. The program cannot keep up with the demand—the wait for a new patient appointment is six to nine months. Most overweight and obese children do not have Type 2 diabetes—yet. But without early and appropriate intervention, they are on course to get the disease.
Successful intervention is hard to attain, however. Changing a child's eating and exercise habits requires evaluation, treatment and teaching by a team of specialists working with the patient and family over a sustained period of time. The OWL team is composed of an endocrinologist, a gastroenterologist, nurse practitioners, a dietitian and behavioral psychologists. According to Ludwig and others, the biggest obstacle to intervention is the unwillingness of health insurers to recognize obesity as a legitimate medical problem. While the obesity epidemic has made the cover of every major U.S. newspaper and magazine over the last few years, physicians still remain powerless to effectively treat obesity. "Untreated Type 2 diabetes becomes a permanent condition that confers enormous risk for heart disease, stroke and other lethal complications," says Ludwig. "Nobody would say to the parents of a child with cancer that since the illness hasn't been controlled in three visits they are cutting off coverage. Yet that is what the managed care industry says about obesity. And a diagnosis of Type 2 diabetes in a child or adolescent carries a worse prognosis than standard-risk ALL [acute lymphoblastic leukemia] when it comes to long-term effects."
Ludwig and many other clinicians feel that, without greater awareness, advocacy and leadership, obesity will become a diabetes epidemic in children and adolescents, and ultimately, according to Ludwig, heart attack will become a disease of young adulthood. At the same time, the public health implications of obesity in children and adults—as well as the attendant costs in terms of health care expenses, lost wages and disability benefits—have outstripped those of smoking. In the meantime, Children's strives to do its part, one patient, one family, one study at a time.
