Diabetes
Based on "Morgan: A case of Diabetes" by Lisa Rubin and Clyde Freeman Herreid (National Center for Case Study Teaching in Science)
The Patient:
Morgan Water is a 27-year old Native American that lives on a reservation in Oklahoma. Nearly ¼ of Morgan's tribe has diabetes but she has no direct family history of diabetes, heart disease, or other serious conditions. She is however obese (BMI = 32) and leads a sedentary lifestyle. Morgan has been suffering from an increasing persistence of symptoms including unusual thirst, dizziness, blurred vision, and numbness in her right foot. The symptoms have been developing over several months but as she is planning her wedding she attributed them to nerves. She is finally persuaded to see her family doctor. Her non-fasting blood glucose level was elevated so the doctor has her return the next morning for a fasting blood sample so they could more accurately measure her blood glucose and insulin. Her blood results are below:
|
Test
|
Morgan's values
|
Normal range
|
Pre-Diabetic range
|
Diabetic range
|
|
Plasma glucose, mg/dl
|
260
|
70 -139
|
140 - 199
|
≥ 200
|
|
Fasting glucose, mg/dl
|
140
|
≤ 99
|
100 - 125
|
≥ 126
|
|
A1C, %
|
7.6
|
~ 5
|
5.7 - 6.4
|
≥ 6.5
|
|
Fasting Insulin, mIU/ml
|
34
|
2 - 10
|
10 - 20
|
≥ 20
|
Question 1:
Based on her history and blood results, what do you think is the most likely diagnosis for Morgan?
A. Type I Diabetes Mellitus
B. Type II Diabetes Mellitus
C. Pre-Diabetes
D. Cardiovascular Disease
Question 2:
What is the cause of Morgan's disease?
A. It is an auto-immune disorder that destroys the β-cells of her pancreas so she produces less insulin than normal.
B. She has a genetic mutation that results in less insulin receptor being produced than normal.
C. She has developed insulin resistance, where her insulin receptors do not recognize the insulin her body produces, likely due to her obesity.
D. There is no known cause, it can happen spontaneously.
Morgan is worried that she will have to spend the rest of her life giving herself injections but her doctor does not prescribe insulin injections.
Question 3:
Why would injections of insulin not help Morgan if she has hyperglycemia?
A. Her body is already producing excess insulin but not responding to it.
B. Her problem is with her insulin receptors responding to insulin.
C. Excess insulin will only exacerbate her insulin resistance.
D. All of the above.
Question 4:
Given Morgan's metabolic state, which of the following pathways would you expect to be active in Morgan's cells (select all that apply)?
A. Glycolysis
B. Gluconeogenesis
C. β-oxidation
D. Amino acid degradation
E. Protein synthesis
The recommendation of Morgan's doctor was to improve her exercise, good nutrition, and weight loss. He recommends meeting with a nutritionist to assist Morgan in her weight loss goals. When Morgan got home and told her family the diagnosis they however had LOTS of suggestions on how she can lose weight. Below is a description of the advice given to her by three family members.
Best friend Savannah:
"You know how I've been losing weight? Well, I've been on the Atkins' Diet. I heard about it on TV. It's great! You get to eat steak, chicken wings, and all the good stuff. All you have to do is limit carbohydrate intake. You should definitely give it a try. This diet has been around for years and it has worked for lots of people, including me."
*Note: Atkin's Diet recommends: 10% carbohydrates, 55% fats, 35% protein
Brother Alan:
"I think the best thing for you to do is exercise and stop eating all of that pizza and candy and food filled with fat. Our people never used to eat that junk. I say eat meals that are nutritionally balanced and high in fiber and low in refined sugars and saturated fats. And run a lot. Stop sitting around the house."
Grandfather:
"Morgan, it is true that it is best to live in harmony and balance - to eat a nutritionally balanced diet that includes carbohydrates, proteins, and 'good' fats to meet your body's needs. That is good. But look to your heritage. Our people were never overweight before we started eating 'civilized' food. Look to our native diet. I think you should look to traditional herbal remedies for help. What Alan says is true. Exercise is good. But it is sometimes not enough. Our people have always looked to natural medicine for cures. They will lift your spirits and energize you. Then you will lose weight and you will be healthy again. I hear the herbs from the diet shop are safe and good. But you must take them like the medicine label says. It can't hurt to try them."
*Note: these herbal supplements Morgan's grandfather is recommending contain the herb ephedra (ephedrine).
Question 5:
Given Morgan's metabolic state, what is the primary fuel source for her cells currently?
A. Carbohydrates (glucose)
B. Fats
C. Proteins
D. It is a balance of all three
Question 6:
Metabolic ketoacidosis is a common problem with diabetics, which is caused by which of the following?
A. Excessive oxidation of fatty acids, leading to an accumulation of ketone bodies in the blood.
B. Excessive oxidation of glucose, leading to an accumulation of ketone bodies in the blood.
C. Excessive oxidation of proteins, leading to an accumulation of ammonia in the blood.
D. Hyperglycemia.
Question 7:
Which weight loss suggestion is designed to achieve some level of ketosis?
A. Atkins Diet
B. Exercise
C. High fiber diet
D. Herbal treatments
Question 8:
One major side effect of the herbal supplement can be hot flashes and increased perspiration due to increased thermogenesis, what is the likely cause of the heat production?
A. Increasing the activity of phosphfructokinase-1.
B. Increasing the activity of the pyruvate dehydrogenase complex.
C. Increasing the activity of citrate synthase.
D. Increasing the activity of uncoupling proteins.
Question 9:
Would substituting fiber and complex carbohydrates (larger % cellulose) for the simple sugars and starches (high sucrose and amylose/amylopectin) help Morgan lose weight, why?
A. Yes, because complex carbohydrates like cellulose are largely indigestible so they pass through the digestive tract without being absorbed.
B. Yes, cellulose contains less glucose residues than amylose or amylopectin.
C. Yes, because the fructose in sucrose is much more responsible for weight gain than the glucose.
D. No, because cellulose, amylose, and amylopectin are all composed of glucose so it doesn't matter.
Question 10:
Which weight loss suggestion will lead to an increased need for gluconeogenesis?
A. Atkins Diet
B. Exercise
C. High fiber diet
D. Herbal treatments