Exam 2 (Lecture 13) - Glucagon and Diabetes Mellitus

Question 1

What is diabetes mellitus and in which species of domestic animals would you most likely encounter this disease?

Answer 1

1) A common endocrine-insulin related disorder in dogs and cats
- 2nd most common endocrinopathy in dogs (hypothyroidism is first)
- together with hypothyroidism, is most common in cats

2) Results from insulin deficiency or decreased response to insulin

3) Characterized by persistent hyperglycemia

Question 2

What are the most common causes of diabetes mellitus in domestic animals?

Answer 2

1) Genetic predisposition

2) Pancreatic injury (autoantibodies is the most common cause of canine hypoinsulemia)

3) Hormone-induced beta-cell exhaustion

Question 3

What is the etiology of DM in humans and what is the etiology of this disease in dogs and cats?

Answer 3

1) Humans:
- DM Type I:
- insulin-dependent diabetes mellitus (juvenile)
- destruction of pancreatic beta-cells (immunological) leads to low levels of insulin
- treatment requires replacement therapy with insulin
- DM Type II:
- non-insulin dependent diabetes mellitus (adult onset)
- combined alteration of insulin sensitivity and insulin secretion
- treated with dietary therapy, oral hypoglycemic agents, and insulin

2) Dogs:
- Hypoinsulinemia (DM type I in humans, most frequent)
- differing degrees of ketosis
- Hyperinsulinemia (similar to DM type II in humans)
- less frequent
- elevated level of growth hormone
- mild clinical signs (ketosis)

3) Cats:
- Analog of human type II
- decreased insulin sensitivity and altered insulin secretion; most common

Question 4

What are the common signs of DM in dogs?

Answer 4

1) cataracts
2) polydipsia
3) anorexia
4) hepatomegaly
5) weight loss
6) depression
7) ketoacidosis
8) hyperglycemia
9) ketonuria
10) glucouria
11) polyuria
12) cystitis

Question 5

Explain general features of pathological processes observed following the insulin withdrawal in DM animals.

Answer 5

Related to the upset balance between effects of insulin and anti-insulin hormones on fuel metabolism.

In the absence of insulin, fuel breakdown processes predominate yielding elevated levels of glucose, ketoacids, amino acids, and free fatty acids.

Question 6

How is DM I usually treated?

Answer 6

Administration of insulin

Question 7

What are the common strategies for DM II treatment?

Answer 7

Complex combinations of:
- weight loss (hormones produced by adipose tissue are associated with insulin insensitivity)
- dietary manipulations (restriction of carb intake, switch to high protein, high fiber and complex carbs)
- Hypoglycemic agents that increase insulin secretion (block K+ channels causing depolarizing beta cells; sulfonylureas), increase insulin sensitivity (stimulate synthesis of enzymes controlled by insulin = Metformin), and decrease glucose absorption in the GI tract (alpha-glucosidase inhibitors)
- insulin administration