diabetes tutorial

Question 1

what effect do incretins have on insulin and glucagon secretion?

Answer 1

• increase insulin
• decrease glucagon

Question 2

what effect does an increase in amino acids have on insulin and glucagon secretion?

Answer 2

• increases insulin secretion
• decreases glucagon secretion

Question 3

what is an example of an insulinotrophic hormones?

Answer 3

GLP-1

Question 4

what effect do you think a Ca2+ ionophore would have on insulin secretion?

Answer 4

it would increase it (as Caq2+ stimulates the exocytosis of insulin from the beta cell)

Question 5

what is the range of a normal fasting blood glucose?

Answer 5

between 3.5-5.6mmol/L

Question 6

what would an abnormal fasting blood glucose be? and if a patient had this value, what other tests should be carried out?

Answer 6

• over 7mmol/L
• patients with this abnormal value should have the test repeated or go on to have an oral glucose tolerance test to assess their glucose handling

Question 7

why is it so important to maintain a blood glucose level of over 3mmol?

Answer 7

to preserve CNS function, as the brain cannot store glucose, it needs a constant supply

Question 8

what 2 measurements from an oral glucose tolerance test can be used to diganose diabetes?

Answer 8

• the fasting blood glucose
• 2hr post meal glucose levels

Question 9

why cant all the body’s energy systems be glycogen?

Answer 9

it would take up too much space (as it attracts water)

Question 10

this chart shows the leves of various glucose regulatory hormones during and after a meal - identify them

Answer 10

• blue - insulin
• green - glucagon
• orange / yellow - epinephrine

Question 11

This chart demonstrates the incretin effect- explain what this means

Answer 11

• the stimulation of insulin with oral as opposed to IV glucose admin

Question 12

examine this hormones profile - can you identify it & what is its function?

Answer 12

• Ghrelin
• stimulates appetite

Question 13

How are ketone bodies produced in type 1 diabetes?

Answer 13

• in type 1 diabetes, the glucose cannot be utilised by the cells, so the body switches to FA oxidation
• the breakdown of fats produces acetyl CoA which can get converted to ketone bodies

Question 14

what can ketone bodies be used for?

Answer 14

metabolic fuel for the brain and other tissues

Question 15

how do ketone bodies cause metabolic acidosis ?

Answer 15

they are organic keto acids (they are also weak acids) and cause metabolic acidosis at concentrations greater or equal to 13mM

Question 16

what is kussmaul respiration?

Answer 16

• the hyperventilatory response (respiratory compensation) for diabetic ketoacidosis

Question 17

what is hyperglycemic hyperosmolar syndrome?

Answer 17

extremely high glucose levels in the blood

Question 18

how do DKA and HHS cause fluid loss (ie increased production of urine - going to the bathroom more often than usual)?

Answer 18

• as both blood glucose and ketone bodies are elevated in the blood
• excessive glucose in the blood will exceed tubular reabsorptive capacity- therefore excess glucose remains in the filtrate, making it hypertonic and causing the movement of water into the renal tubules by osmosis
• this leads to increased volume of urine (polyuria)

Question 19

how does polyuria lead to excessive thirst (POLYDIPSIA)?

Answer 19

• Excessive fluid loss can lead to dehydration and trigger thirst mechanisms

Question 20

what other serious chronic complications (other than DKA in T1DM and HHS in T2DM) can be seen in both types of diabetes as a result of poor hyperglycemic control?

Answer 20

1. microvascular - retinal , renal and peripheral neuropathy
2. macrovascular - coronary heart disease and stroke

Question 21

why would the blood glucose levels be elevated in type 1 diabetes ? (be detailed)

case study q’s - see tutorial notes

Answer 21

• Type 1 diabetes is an autoimmune disease which leads to the destruction of pancreatic beta cells
• this leads to insulin deficiency
• as a result of insulin deficency, the glucose in the blood cannot be utilised by the cells and cannot be lowered - leading to hyperglycemia
• also the deficiency of insulin stimulates the counter regulatory hormones eg glucagon, epinephrine which raise glucose levels even further

Question 22

in a patient with diabetic ketoacidosis, why is her PH decreased?

Answer 22

• insulin normally stimulates the synthesis of fatty acids, however due to the deficiency in T1DM, glucagon and epinephrine stimulate fatty acid oxidation
• FA break down to acetyl CoA which can be converted to ketone bodies
• ketone bodies are weak acids that result in the PH becoming more acidic

Question 23

why would a patient with diabetic ketoacidosis be breathing rapidly? explain this mechanism and what happens as a result

Answer 23

• this is called Kussmaul’s respiration
• it is a compensatory mechanism as a result of diabetic ketoacidosis
• the hyperventilation decreases the CO2 in the blood, shifting the equilibrium to the left of the H2CO3 equation, therefore reducing H+ ions and reducing PH

Question 24

how is uncontrolled type 1 diabetes mellitus similar to starvation?

Answer 24

• starvation and T1DM are conditions in which the insulin/ glucagon ratio are very low (ie insulin is low)
• in uncontrolled DM, glucagon activity increases and raises blood glucose levels , however the tissues that are dependent on insulin for glucose uptake cannot do so and are effectively starving - ie muscles