Diabetes (Exam IV) Flashcards
What are the two types of secretory tissue found in the pancreas?
What are the functions of these two tissues?
- Exocrine Glands - Digestive enzymes
- Endocrine Glands - Hormones
What tissue type is located in the endocrine portions of the pancreas that produces secretory hormones? What cells make up this tissue.
Islet of Langerhans
- Alpha cells
- Beta cells
- Delta cells
- G cells
- F cells
What is produced in the Αlpha cells of the Islet of Langherhans?
What about the Βeta cells?
What about the Delta cells?
- α → Glucagon
- β → Insulin & Amylin
- δ → Somatostatin
How does proinsulin become insulin?
- Proinsulin is cleaved into Insulin and C-peptide.
What does Amylin do?
- Amylin is inhibitory to Glucagon (and a little to insulin as well)
What does Somatostatin do?
- Short acting (5min) inhibitory effect on both insulin & glucagon right after eating.
What receptor type are insulin receptors? What do they do when bound with insulin?
- Tyrosine Kinase Receptors
- Phophorylate effector proteins to promote GLUT transporters to bind to the cell surface.
What is the homeostatic level of blood glucose?
90mg/100mL
How quickly is glycogen used up?
Completely used up in 24 hours.
Why type of receptor is a glycogen receptor?
What organ takes in glycogen for energy storage & also breaks it down for use?
- GPCR.
- Liver.
What signs/symptoms are characteristic of diabetes mellitus? (particularly type I)
- Polyuria, Polydipsia, & Polyphagia
What characterizes Type 1 DM?
- Autoimmune destruction of βcells in the pancrease. Insulin dependent.
What characterizes Type 2 DM?
- Usual metabolic syndrome, non-insulin dependent but will convert to Type I if untreated.
What characterizes Type 3 DM?
- Temporary ↑ BG (pancreatitis, drug therapy, etc.)
What characterizes Type 4 DM?
- Gestational
At what level of βcell destruction is a diagnosis of Type I DM official?
What two types of Type 1 DM exist & which is more common?
- 80% of βcells destroyed.
1. Immune (more common)
2. Idiopathic (genetic)
Why do Type 1 diabetics often have weight loss?
What might occur if a Type 1 diabetic is not given insulin replacement.
- Due to the inability to process carbohydrates.
- Fatty acid oxidation → ↑ketones → ↓pH
Which Diabetes Mellitus sub-type is characterized by relative deficiency of insulin secretion & tissue insulin resistance?
What occurs at the cellular level with insulin resistance?
What would blood levels of insulin be in a type 2 DM patient?
- Type II DM (the artist formerly known as “adult onset DM”)
- Downregulation of GLUT transporters.
- Initial ↑ insulin level; ↓ insulin level developed over time.
What blood glucose levels would you expect to see with non-ketotic hyperosmolar syndrome?
What symptoms would be associated with this condition?
> 600mg/dL
- Dehydration & eventual coma/death.
What are three clinical manifestations of chronic type 2 DM?
- Recurrent infections
- Vision problems
- Neuropathy
What is nonenzymatic glycosylation?
- The process by which chronically high blood sugars attach to your hemoglobinA1C.
What is a normal Hemoglobin A1C?
What is a very abnormal one?
4-5%
> 7%
Describe the hyperglycemic effect on the polyol pathway.
Where is this effect most prominent?
- Sorbitol & Fructose increase intracellularly = ↑ osmotic pressure = Hypotonicity of the cell & cell rupture.
- Eye lens, nerves (neuropathy), & RBCs (anemia)
What microvascular areas of damage are associated with Type 2 DM?
- Diabetic Retinopathy
- Diabetic Nephropathy
What are the results of gestational diabetes mellitus?
- ↑ child birth weight
- ↑ risk for 2nd pregnancy
- ↑ risk for development of Type 2 DM.
What should a fasting blood glucose be in a healthy individual?
Describe the glucose tolerance test.
- < 100 mg/dL
- A sugary drink is imbibed and blood glucose levels are drawn 1-2 hours post ingestion. More definitive than a fasting level.
Porcine insulin administration can cause local ______ at the injection site.
atrophy
What are insulin secretagogues?
What non-drug insulin secretagogues should be known?
- Anything that causes insulin release
1. Glucose
2. Amino acids
3. Hormones
4. Fatty acids
5. Incretins
What drugs were noted in lecture to be insulin secretagogues?
- Sulfonylureas
- Isoproterenol
GLUT-4 has an _______ affinity for glucose.
GLUT-2 has a _______ affinity for glucose. What does this mean?
- Intermediate
- Low; this means that high levels of blood glucose are required to stimulate this transporter.
What is the complete process for how insulin is stimulated & released from a cell via extracellular glucose?
- ↑ ECF glucose
- Glucose brought to ICF via GLUT
- Glucose metabolized & ATP created
- ↑ ATP closes K⁺ rectifying channels
- Closed K⁺ channels = depolarization
- Depolarization = ↑ pCa⁺⁺
- ↑ pCa⁺⁺ = VP1 → VP2 & vesicular release of insulin via exocytosis.
What effects are elicited by insulin reacting with the insulin tyrosin kinase receptor?
- ↑ uptake of glucose via more GLUT proteins
- ↑ glycogen formation
- Activation of more transcription factors.
What GLUT transporters have a very high affinity?
- GLUT-3; Brain
What GLUT transporters have a very low affinity?
- GLUT-2; β cells of pancrease, liver, & kidney
What GLUT transporters have an intermediate affinity?
- GLUT-4; Muscles & adipose tissue.
What are the 3 endocrine effects of insulin?
- ↓ glycogenolysis = ↓ release of liver glucose.
- ↓ conversion of fatty acids & amino acids to keto acids.
- ↑ glycogen formation/storage.
What non-drug factors inhibit insulin secretion?
- Insulin itself, Leptin, SNS activity, chronically high glucose, & amylin
What drugs inhibit insulin secretion?
What type of DM do these then cause?
- Diazoxide, phenytoin, vinblastine, colchicine
- Type III DM
70/30 insulin is a combination of what?
How effective is the combination?
Combo:
- Short acting (regular)
- Intermediate acting (Neutral protamine hagedorn NPH).
The 70/30 combo is decent but not as good as a basal/bolus method with rapid-acting & long-acting.
Why is nasal insulin not in more frequent use?
Nasally administered insulin causes bronchoconstriction.
What method is preferable for tight blood glucose level control?
- Continous subcutaneous insulin infusion devices (CSIID)
- Basal Bolus method with long acting (next best)
1 unit of rapid-acting insulin “covers” how many carbs that are eaten?
- 1 unit RA insulin = 12-15g carbs (ex. 75g carb meal requires 5 units RA insulin)
1 unit of rapid-acting insulin drops blood glucose by _____ mg/dL.
- 50mg/dL
When metabolic rate increases, what occurs with insulin requirements?
- Insulin requirement increases as well
At what blood glucose level is one considered hypoglycemic?
- < 60mg/dL
What drug class is first-line therapy for DM?
What drug is prototypical of this class and what is its mechanism of action?
What is a normal dose & what is the max dose where one would want adjunct therapy?
- Biguanides =Metformin
- Reduces hepatic glucose production
- Dosing starts at 500mg & maxes out at 2500mg/day
What drug classes are insulin secretagogues? Which of these can have trigger sulfa- allergies?
What is this drug classes MOA?
- Sulfonylureas (sulfa)
- Meglitinide
- Phenylalanine derivatives
- MOA: Binds to rectifying K⁺ channel in pancreatic β cell decreasing threshold & causing depolarization. Depolarization causes Ca⁺⁺ influx & vesicular release of insulin.
1st generation sulfonylureas have a ______ dose than 2nd generation sulfonylureas. What does this mean for safety?
- higher
- 1st generation have a higher doses = more side effects. 2nd generation is safer with its lower doses.
Which sulfonylurea is associated with bad outcomes and increased instances of MI?
- Tolbutamide.
Which class of insulin secretagogues has much less efficacy due their very short T½ & duration of action?
- Meglitinides
What is the mechanism of action for Thiazolidinediones (Tzd’s)?
What is the prototypical drug of this class & what is the main risk associated with it?
- ↓ insulin resistance by ↑ GLUT-4 prevalence.
- Rosiglitazone = risk of MI, especially with nitrate & insulin use.
What is the mechanism of action of α-glucosidase inhibitors?
When is this drug beneficial?
What side effects are typical?
- Blockade of digestion of complex carbs & thus blocking uptake of glucose.
- Drug is beneficial in pre-diabetics & high starch diets. (think Japan)
- GI problems (flatulence, diarrhea, etc.)
What is the mechanism of action of bile-acid binding resins?
What side effects are typical?
- BABR’s bind to food & prevent absorption of glucose.
- GI upset.
How do Amylin Analogs treat DM?
What is this drug’s route of administration?
Where is Amylin naturally produced in the body?
- ↓ glucose release.
- IV/IM (not oral)
- Amylin is produced in the βcells of the pancreas.
What drug class treats DM through the usage of GI hormones?
What are these specifically & their MOA’s?
What risk (though small) is conferred by these drugs?
- Incretin-based therapies.
- GLP-1 (Glucagon-like polypeptide-1) = stimulates insulin release & inhibits glucagon release.
- DPP-4 (Dipeptidyl Peptidase-4 Antagonist) = blocks breakdown of GLP-1
- Pancreatic cancer.
Gliflozins are also known as ______ ________.
What suffix is denoted by this drug class?
- SLGT2 Inhibitors
- -flozin
How do Gliflozin’s work?
What is the result of this & what side effects can occur?
- Prevention of glucose reabsorption in the PCT
- Glycosuria (perineal necrosis, ↓BP, weight loss, & dehydration).
Where do SLGT-2 inhibitors work in the kidneys?
How much glucose is reabsorbed despite administration of these drugs?
- S1 segment of the PCT.
- 20-30% glucose reabsorption in S2 (increased by SLGT-2 inhibition, normally 10% in S2 segment)