Topic 2 - Diabetes Flashcards
What occurs to Carbs, Fat, and Protein during the Absorptive State?
Carbohydrates –> Converted into glucose and fat as major energy source
Fat –> Triglyceride synthesis and storage
Protein –> Protein synthesis, Excess converted and stored as triglyceride fat
What happens to the three main metabolic fuels during the Postabsorptive state?
Carbohydrates –> Glycogen degradation
Fat –> Triglyceride catabolism, Fatty acids provide major energy source for non glucose-dependent tissues
AAs –> gluconeogenesis
What do Beta cells secrete?
Secretory granules containing inactive C-peptide, insulin, and Amylin
How is proinsulin converted into insulin?
Cleaved by C-peptide
What do Alpha cells secrete?
Glucagon
What is the anabolic hormone?
Insulin
Why do elevated amino acid levels trigger the release of insulin?
Insulin is involved in the removal of amino acids and free fatty acids.
Why is it so important to maintain BGL?
Glucose is the brain’s only energy source, and it does not store glycogen.
How does adipose tissue affect metabolism?
Adipose tissue is the main energy storage site, it regulates fatty acid levels in the blood.
How does the liver affect metabolism?
The liver’s primary role is to maintain normal BGL. Promotes interconversions such as gluconeogenesis.
How does muscle affect metabolism?
Skeletal muscle is the primary site of AA storage as well as a major energy user
What is the role of incretins in regulating blood sugar? When are they released?
Incretins, such as GIP and GLP-1 are released after eating food. They exacerbate insulin secretion.
Why do elevated AA levels trigger glucagon secretion?
Protein rich meals require energy to be digested and for their energy to be used. Release of glucagon primes the body to metabolize AAs.
What are some examples of insulin’s counter-regulatory hormones?
–> Growth hormone
–> Glucocorticoids (Cortisol)
–> Adrenaline
What is Stress Induced Hyperglycaemia?
Stress hormones increase glucose production in the liver and decrease glucose use. E/NE increase FFAs in blood and inhibit peripheral glucose uptake.
How does exercise affect insulin levels?
Insulin levels decrease and glucagon levels increase. Additionally, muscle contractions increase insulin sensitivity, which maintains normal BGL in the presence of lower insulin levels.
What is Amylin?
A hormone secreted with insulin by Beta Islets. It inhibits gastric emptying and suppresses glucagon release.
Describe the process of how Beta Cells secrete insulin
- Glucose binds to GLUT 1
- Glucose is converted to ATP
- ATP activates K+ channel
- Cell depolarizes
- Ca2+ Channel opens
- Increased Ca2+ triggers exocytosis of insulin + amylin + C-peptide granule
Describe both phases of insulin secretion
1st Phase - Incretin hormones (GIP + GLP) trigger spike in insulin levels 3-5 minutes after eating. Release of preformed insulin
— Small drop in levels —
2nd Phase - At around 15 minutes the insulin secretion rises again and reach a new plateau in 2-3 hours. Most of this insulin is newly produced.
Describe the three kinds of insulin independent Glucose Transporters.
GLUT 1 - Makes blood brain barrier + B cells
GLUT 2 - Small amount in B cells
GLUT 3 - Pancreatic B cells + predominantly neurons
What kind of Glucose transporter is insulin dependent? Where are they found?
GLUT 4 - Muscle and Adipose Tissue
Where is GLUT 4 located? What is the advantage of this?
Located in the cells cytoplasm and packaged into vesicles. This way, transporters do not need to be manufactured, just implemented into their correct location.
What happens to an insulin receptor after it binds with insulin?
Insulin-receptor complex enters the cell via endocytosis.
–> Receptors are recycled to the cell surface
–> Insulin is degraded in lysosomes
What is the definition of diabetes? What is this condition characterized by?
Diabetes Mellitus is a glucose tolerance disorder characterized by hyperglycemia.
What kind of situations can cause secondary diabetes mellitus?
–> Pancreatic diseases
–> Diseases of the endocrine glands
–> Drug induced
What kinds of medication might cause secondary diabetes?
Corticosteroids used to treat severe asthma
What is acromegaly? Why might it cause secondary diabetes?
Excessive HGH, which inhibits insulin secretion
What is Cushing’s syndrome? Why might is cause secondary diabetes?
Excessive cortisol production, which increases gluconeogenesis and decreased peripheral glucose utilization.
What might cause glucose oversecretion?
Tumors of the A cells which increases glucagon secretion and gluconeogenesis.
What is a FPG? What are normal values for this test?
A fasting plasma glucose test. Patient is not allowed to eat for 8 hours, after which glucose levels are taken. Any measurement below 5.6 mmol/L indicates normoglycemic levels. Measurements between 5.6-6.9 indicate impaired fasting glucose (IFG) and any measurement of 7.0 or higher indicates DM.
What is a 2-OGTT? What are normal values for this test?
Patient is given oral glucose dose of 75 grams and their GBL is taken after two hours. Any measurement lower than 7.8 mmol/L indicates normoglycemic levels. 7.8-11.0 indicates high levels, and any measurement of 11.1< indicates DM
What is an HbA1C test?
A test to determine the amount of Glycosylated hemoglobin (A1c, or the amount of Hb with glucose attatched in bloodstream). High levels (>6.5%) indicate chronically high BGL.
Why is more insulin secreted after an oral dose vs an IV push?
Incretins, which exacerbate insulin secretion, are released only when food is eaten.
DM1 is characterized by hyperglycemia due to _____
Insulin deficiency
What is Type 1B DM?
Idiopathic DM, or degeneration of the B cells without a know autoimmune cause.
What is Type 1A DM?
Autoimmune destruction of B cells.