Chapter 113 Complicated Diabetes Mellitus

Question 1

What are the two forms of complicated diabetes mellitus?

Answer 1

DKA and HHS (hyperglycemic hyperosmolar syndrome)

Question 2

What is the criteria for HHS?

Answer 2

Severe hyperglycemia (>600 mg/dL), minimal or absent serum or urine ketones and severe hyperosmolality (>350 mOsm/kg)

Question 3

What are the mechanisms that insulin deficiency promotes hyperglycemia?

Answer 3

1. Promotes gluconeogenesis
2. Promotes glycogenolysis
3. Reduces cellular utilization of glucose

Question 4

Free fatty acids can be broken down into what ketone bodies?

Answer 4

Acetoacetate
Beta-hydroxybutyrate
Acetone

Question 5

What else are FFA broken down into (other than ketones)?

Answer 5

Triglycerides, CO2, water

Question 6

Describe the mechanism for which an uncomplicated DM turns into a DKA?

Answer 6

• When there is a concurrent streeors - counterregulatory hormones glucagon, epinephrine, cortisol and growth hormone are produced.
• These counterregulatory hormones contribute to glucose production, insulin resistance and protein catabolism
• Counterregulatory hormones ALSO contribute to lipolysis, leaving more FFA than usual available to form ketone bodies
• DKA occurs once the amount of ketoacids overwhelms the metabolic pathway that converts ketones to energy as well as the buffering system that normally mitigates the effects of ketones on acid-base status

Question 7

What limits ketosis in HHS?

Answer 7

Small quantities of circulating insulin and hepatic glucagon resistance that inhibits lipolysis

Question 8

What are the contributing factors for the massive hyperglycemia with HHS?

Answer 8

Progressive osmotic diuresis, dehyrdration, subsequent decrease in GFR

Question 9

The lower the GFR, the ______ the blood glucose concentration.

Answer 9

Higher

Question 10

True or false: anemia blood has a falsely decrease plasma glucose.

Answer 10

False: increased plasma glucose is seen in anemia patients.

Question 11

What is documented serum osmolality cutoff for when neurologic signs are seen?

Answer 11

340 mOsm/kg

Question 12

What is the effective osmolarity equation? (meaning BUN not taken into account)

Answer 12

2(Na) + (glucose/18)

Question 13

What is the underlying pathophysiology of pseudohyponatremia with DKA/HHS?

Answer 13

Hyperglycemia and hyperosmolality exerts an osmotic force that pulls water into ECF, causing an increase in plasma water that dilutes the sodium

Question 14

What is the equation for corrected sodium?

Answer 14

1.6 x [(measured glucose - normal glucose)/100] + measured Na

Question 15

What are the mechanisms leading to hypokalemia in DKA/HHS?

What 2 other electrolytes are affected via similar mechanisms?

Answer 15

1. Insulin deficiency: decreases amount of potassium co-transported into cells
2. Acidemia: causes potassium to shift out of cells in exchange for hydrogen ions
3. Severe hyperosmolality: leads to shift of potassium out of cells
4. Hypovolemia-induced hyperaldosteronism: increases renal potassium loss
5. Decreased intake/GI losses

Magnesium and phosphorus