L35- Diabetes

Question 1

Which type of diabetes results from a loss of beta-cells in the pancreas, leading to a defect in the production of insulin?

Answer 1

Type I diabetes (also called insulin-dependent diabetes).

Question 2

Which type of diabetes results from a defect in the response to insulin?

Answer 2

Type II diabetes (also called insulin-independent diabetes).

Question 3

What is most common type of diabetes in the United States?

Answer 3

Type II diabetes constitutes approximately 90% of diabetes cases.

Question 4

A diabetic patient presents to your clinic with ketoacidosis. Which type of diabetes do you suspect?

Answer 4

Type I diabetes mellitus.

Question 5

A 50 year-old diabetic patient presents to your clinic with high blood levels of insulin. Which type of diabetes do you suspect?

Answer 5

Type II diabetes mellitus.

Question 6

What is the normal value for fasting plasma glucose (in mg/dl)?

Answer 6

Values less than 100mg/dl.

Question 7

A value of fasting plasma glucose greater than ___ mg/dl would be considered consistent with diabetes.

Answer 7

125 mg/dl.

Question 8

What value of blood glucose would a diabetic patient have (in mg/dl) two hours after a glucose challenge?

Answer 8

A value greater than 200 mg/dl.

Question 9

Which glycolytic enzyme found in pancreatic beta-cells is stimulated by a rise in blood glucose concentrations and is involved in the release of insulin?

Answer 9

Glucokinase.

Question 10

Which membrane channels directly control the secretion of insulin from beta-pancreatic cells?

Answer 10

Ca++ channels.

Question 11

Glucose stimulates a rise in intracellular ATP in beta-pancreatic cells. Which channels are directly affected by this rise in ATP and what is their function?

Answer 11

ATP-dependent K+ channels. Binding of ATP to these channels causes the cell to depolarize. This triggers the opening of voltage-dependent Ca++ channels that in turn stimulate insulin secretion.

Question 12

Which group of drugs act at K+ channel inhibitors and can therefore be used to enhance insulin secretion?

Answer 12

Sulfonylureas.

Question 13

True or False. Injected glucose stimulates a much greater insulin response than ingested glucose.

Answer 13

False. Oral glucose stimulates a greater response than injected glucose.

Question 14

Name two incretins released from the gastrointestinal tract that stimulate insulin secretion.

Answer 14

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide hormone (GIP).

Question 15

Through which signaling molecule and channels found in beta-pancreatic cells do incretins exert their effect?

Answer 15

PKA and potassium/calcium channels.

Question 16

What is the function of the drug sitagliptin?

Answer 16

It inhibits the protease that degrades incretins, leading to a longer insulin response. It is useful to treat Type II diabetes.

Question 17

Which family of receptors bind to insulin?

Answer 17

Tyrosine kinases.

Question 18

How does insulin decrease blood glucose concentrations?

Answer 18

By increasing glucose uptake in muscle and adipose tissue.

Question 19

What is the effect of insulin on lipoprotein lipase?

Answer 19

It increases lipoprotein lipase activity.

Question 20

What is the effect of insulin on glycogen phosphorylase and glycogen synthetase?

Answer 20

Insulin decreases the activity of the phosphorylase and increases the activity of the synthetase.

Question 21

What is the effect of insulin on the gluconeogenic pathway?

Answer 21

It decreases gluconeogenic reactions.

Question 22

What is the effect of insulin on fatty acid synthesis in the liver?

Answer 22

It increases fatty acid synthesis.

Question 23

What is the effect of insulin on hormone-sensitive lipase?

Answer 23

It decreases hormone-sensitive lipase activity.

Question 24

Which glycolytic enzyme is directly regulated by insulin?

Answer 24

Phosphofructokinase-2.

Question 25

Name an anti-diabetic drug that reduces liver gluconeogenesis by acting through an AMP-dependent protein kinase.

Answer 25

Metformin.

Question 26

Which enzyme in fatty acid metabolism is directly regulated by insulin?

Answer 26

Acetyl-CoA carboxylase.

Question 27

Loss of insulin leads to the overproduction of which ketone bodies?

Answer 27

Acetoacetate and beta-hydroxybutyrate.

Question 28

In cases of ketoacidosis, which important cations are overexcreted in the urine along with ketone bodies?

Answer 28

Potassium and sodium.

Question 29

What is the “diabetes lipid triad”?

Answer 29

1. Elevated triacylglycerides, 2. Low HDL, and 3. Small, dense LDL.

Question 30

Which medical emergency can result from uncontrolled Type II diabetes?

Answer 30

Non-ketotic hyperosmolar hyperglycemic coma (HONK).

Question 31

List three cytokines produced by adipose tissue that can promote insulin resistance.

Answer 31

Adiponectin, IL-6 and TNF-alpha.

Question 32

How may hyperglycemia lead to the generation of reactive oxygen species (ROS)?

Answer 32

ROS can be generated when glucose interacts with transition metals.

Question 33

Accumulation of which glucose metabolite may contribute to the development of cataracts in states of hyperglycemia?

Answer 33

Sorbitol.

Question 34

True or False. Hyperglycemia increases the NADH/NAD+ ratio.

Answer 34

True.

Question 35

Which blood component can be measured to monitor long-term control of blood glucose levels in diabetic patients?

Answer 35

Hemoglobin-A1c (HbA1c).

Question 36

Glycation of which protein inhibits the uptake the LDL in states of hyperglycemia?

Answer 36

Apolipoprotein B.

Question 37

What are some initial symptoms of hypoglycemia when blood glucose levels fall below 60mg/dl?

Answer 37

Sweating, anxiety, palpitations, hunger and tremors.

Question 38

Below which blood glucose concentrations (in mg/dl) can a patient fall into a coma?

Answer 38

30 mg/dl.