Lecture 15 4/4/25

Question 1

What are the mechanisms of hypoglycemia?

Answer 1

-decreased glucose production
-excessive use of glucose
-excess insulin or insulin-like substances

Question 2

What are the characteristics of insulinoma?

Answer 2

-functional insulin-secreting tumor of pancreatic beta cells
-inappropriate insulin secretion in the face of hypoglycemia
-might appear clinically “normal” with mild to moderate hypoglycemia

Question 3

What can cause false hypoglycemia on bloodwork?

Answer 3

-delayed sample handling (most common)
-improper measuring technique/equipment
-profound leukocytosis or polycythemia

Question 4

What are the characteristics of stress hyperglycemia?

Answer 4

-transient increase in blood glucose that occurs in response to stress or illness
-usually mild, but can be pronounced (esp. in cats)
-no clinical signs

Question 5

What is diabetes mellitus?

Answer 5

-disease of insulin deficiency
-characterized by hyperglycemia resulting from inadequate insulin secretion, action, or both

Question 6

What is type 1 diabetes mellitus?

Answer 6

-insulin-deficient
-beta cell related disorders

Question 7

What is type 2 diabetes mellitus?

Answer 7

-insulin-resistant
-target organ disorders

Question 8

What are the characteristics of type 1 diabetes mellitus?

Answer 8

-absolute insulin deficiency with no endogenous insulin production
-multifactorial etiology that is poorly understood

Question 9

What are the potential pathologies of type 1 diabetes mellitus?

Answer 9

-complete absence of pancreatic beta cells
-reduced number/size of pancreatic islets
-decreased number of beta cells
-beta cell vacuolation and degeneration

Question 10

What are the characteristics of an immune-mediated etiology of diabetes mellitus?

Answer 10

-uncommon in dogs
-production of autoantibodies
-dog-leukocyte antigen genes encode MHC that can increase risk or be protective

Question 11

Which breeds are predisposed to diabetes mellitus?

Answer 11

-samoyed
-westie
-mini poodle

Question 12

Which exocrine pancreatic diseases can cause a loss of beta cells?

Answer 12

-pancreatitis
-neoplasia
-idiopathic

Question 13

What are the characteristics of the relationship between pancreatitis and diabetes mellitus?

Answer 13

-pancreatitis is estimated to be present in 30 to 40% of dogs with DM
-“bystander” damage to islets can result in DM
-hyperglycemia and hyperlipidemia can cause pancreatitis

Question 14

What can cause congenital DM?

Answer 14

-beta cell aplasia/atrophy/hypoplasia
-defects in beta cell function
-defects in insulin action

Question 15

What can cause insulin-resistant DM?

Answer 15

-growth hormone
-steroids
-progesterone/progestins

Question 16

What are the classifications of DM?

Answer 16

-beta cell related disorders
-congenital
-insulin-resistant

Question 17

What are the key points regarding type 1 DM?

Answer 17

-loss of beta cells
-requires exogenous insulin
-generally irreversible; requires life long treatment

Question 18

What can contribute to decreased tissue responsiveness to insulin/insulin resistance?

Answer 18

-obesity
-physical inactivity
-sources of inflammation
-diabetogenic drugs
-patient genetics

Question 19

What is the cycle of beta cell failure?

Answer 19

-insulin resistance leads to impaired beta cell function and beta cell failure
-beta cell failure results in inadequate insulin secretion and decreased glucose tolerance
-decreased glucose tolerance leads to DM and gluco(lipo)toxicity
-gluco(lipo)toxicity leads to further beta cell failure

Question 20

Why is type 2 DM considered potentially reversible?

Answer 20

-removing cause of insulin resistance can improve tissue sensitivity
-can have less hyperglycemia and reduced glucotoxicity
-can enter remission and no longer have a need for exogenous insulin

Question 21

What are the characteristics of DM secondary to hypersomatotropism in cats?

Answer 21

-up to 25% of diabetic cats
-must be on insulin for 6 weeks prior to testing
-diagnosed via increased serum IGF-1
-treatment of excessive growth hormone allows for higher DM remission rates

Question 22

What are the characteristics of DM secondary to Cushing’s in cats?

Answer 22

-Cushing’s is rare in cats
-nearly 80% of cats with Cushing’s also have DM
-treatment of Cushing’s does not typically reverse DM

Question 23

What are the characteristics of DM secondary to Cushing’s in dogs?

Answer 23

-only occurs in about 8% of Cushing’s dogs
-unknown why some develop DM and others do not
-uncontrolled Cushing’s makes DM more difficult to control

Question 24

What are the characteristics of gestational diabetes?

Answer 24

-occurs during diestrus or gestation
-progesterone stimulates growth hormone secretion; both can cause insulin resistance
-potentially reversible; must spay immediately and start animal on insulin

Question 25

What is the summary for type 1 DM?

Answer 25

-no endogenous insulin production -absolute insulin deficiency -no insulin resistance -absolute insulin dependency -no chance for remission -mostly seen in dogs

Question 26

What is the summary for type 2 DM?

Answer 26

-possible to have some endogenous insulin production -relative insulin deficiency -insulin resistance is common -possible insulin dependency -chance for remission -mostly seen in cats

Question 27

What are the signs of insulin deficiency?

Answer 27

-hyperglycemia -glucosuria -polyphagia -PUPD

Question 28

What are the characteristics of glucose in the kidney?

Answer 28

-glucose is freely filtered and 100% reabsorbed in proximal tubule -primarily via SGLT-2

Question 29

What is the renal glucose threshold in dogs and cats?

Answer 29

dogs: 180 to 200 mg/dL cats: 250 to 300 mg/dL

Question 30

Why does mild hyperglycemia not lead to DM?

Answer 30

-often associated with stress -levels less than renal threshold allows for all filtered glucose to be absorbed -no clinical signs occur

Question 31

What happens when the hyperglycemia is above the renal threshold?

Answer 31

-glucosuria -osmotic diuresis -PUPD

Question 32

What are the consequences of insulin deficiency?

Answer 32

-poor wound healing -catabolism and weight loss -amino acids being directed into gluconeogenesis

Question 33

What are the hallmark clinical signs of DM?

Answer 33

-typically acute onset -systemic illness/diabetic ketoacidosis

Question 34

What are potential complications of DM?

Answer 34

-infections -delayed wound healing -diabetic cataracts

Question 35

What are the characteristics of diabetic cataracts?

Answer 35

-common in dogs; 80% of patients develop them within 1 year -rare in cats -not related to glycemic control -changes in lens osmolarity lead to influxes of water, rupture of lens fibers, and lens-induced uveitis

Question 36

What are the possible PE findings in DM patients?

Answer 36

-obesity -weight loss if dz untreated for long time -possible hepatomegaly -possible dull, dry, brittle hair coat -possible secondary infections

Question 37

What is the diagnostic criteria for diagnosing DM in dogs?

Answer 37

-blood glucose >/= 200 mg/dL AND clinical signs OR -hyperglycemic crisis/DKA

Question 38

What is the diagnostic criteria for diagnosing DM in cats?

Answer 38

-blood glucose >/= 270 mg/dL AND clinical signs AND -either increased glycated proteins or glucosuria OR -hyperglycemic crisis/DKA

Question 39

What are the characteristics of fructosamine?

Answer 39

-glycosylated albumin that reflects average BG over the life-time of albumin -higher values in cases of poor glycemic control -not affected by stress -less reliable for monitoring of treatment

Question 40

What are the characteristics of Hb A1C?

Answer 40

-glycosylated hemoglobin that assesses glycemic control over lifespan of RBC -gold standard in humans -not widely used in vet med

Question 41

What is clinical DM diagnosis based on?

Answer 41

-clinical signs -persistent hyperglycemia -persistent glucosuria

Question 42

What is the minimum diagnostic info needed to diagnose diabetes mellitus?

Answer 42

-blood glucose -urine dipstick

Question 43

What other diagnostics are ideal when diagnosing DM?

Answer 43

-CBC -chem/lytes -UA -blood pressure -fructosamine -urine culture -total T4 (cats)