Exam 4 - Feline Diabetes Mellitus Flashcards
what signalment of cat is most at risk for feline diabetes mellitus?
older indoor male cats are most at risk!
T/F: many cats exist in a pre-diabetic/diabetic state for long periods prior to diagnosis
true
why can diagnosing diabetes in cats challenging?
stress in cats can cause substantial hyperglycemia
what are the 3 main causes of feline diabetes?
- sustained insulin release - most common, similar to type 2 in humans
- secondary to chronic pancreatic disease
- type 1 diabetes mellitus - immune mediated destruction, very rare in cats
what genetic predispositions for diabetes have been identified in cats?
european & australian burmese cats
what is the pathogenesis of how sustained insulin resistance leads to the development of feline diabetes mellitus?
insulin resistance initially drives an increase in insulin secretion which results in the deposition of islet amyloid polypeptide (IAPP) within the pancreas
IAPP is co-secreted with insulin - it slows gastric emptying & enhances feelings of satiety
pancreatic amyloidosis impairs beta cell function
what is the pathogenesis of how chronic pancreatic disease leads to the development of feline diabetes mellitus?
persistent inflammation of the exocrine pancreas damages the islets
what is insulin resistance? how is this a problem in cats with diabetes?
insulin sensitivity reflects the responsiveness of the tissues to the insulin - insulin attaches to cell surface receptors which triggers a series of intracellular events (glucose channels are opened & glucose enters cells)
in diabetic cats, numerous factors make it more difficult for this process to work as intended - insulin resistance means it takes more insulin to get the job done
T/F: there is a 4 fold increase risk of diabetes mellitus if a cat is obese
true
what is the number one cause of insulin resistance in cats?
obesity!!!
how can lack of exercise/poor muscle mass cause insulin resistance?
muscle is a great sink for glucose - loss of muscle tissue & a sedentary lifestyle can cause insulin resistance
how do inflammatory conditions cause insulin resistance in cats?
cytokines antagonize the effects of insulin - conditions like chronic pancreatitis, chronic stomatitis, & chronic cholangitis
acute inflammation can impact insulin sensitivity in the short term
what drugs can cause insulin resistance in cats?
glucocorticoids - prednisolone, depomedrol
progestagens - megestrol acetate
how can acromegaly cause insulin resistance in cats?
usually caused by growth hormone secreting pituitary tumor
growth hormone is a powerful antagonist to insulin
how does diet type influence diabetes mellitus in its development?
secretion of key hormones from gi tract influenced by diet type
hormones impact insulin secretion & hepatic gluconeogenesis - important for efficient handling of ingested nutrients - these hormones are called incretins
what are the incretins?
glucose-dependent insulinotrophic peptide (GIP)
glucagon-like peptide (GLP-1) - most important one with respect to pancreatic health, powerful trophic effect on beta cells
what are the best stimuli for incretins in cats?
fats & proteins!
high carb diet - results in poor incretin release & compromised beta cell health
diets with <14% of metabolizable energy from carbs are recommended
what are the steps of getting to diabetes mellitus starting with insulin resistance?
pancreas has to secrete more insulin to maintain euglycemia - amylin (IAPP) is co-secreted with insulin, but in cats & people, it gets stuck in pancreas resulting in pancreatic amyloidosis leading to compromise in beta cell function
eventually insulin production is not enough to maintain euglycemia - BG will go out of reference range but stays in renal threshold (pre-clinical DM) - need to intervene if we see a cat in this state by changing diet/addressing obesity
BG >200 mg/dl causes glucose toxicity (but cat is not overtly diabetic) - damages many cells but particularly nerves, causing diabetic neuropathy & causes apoptosis of beta cells (not all die, some can be coaxed back to life)
when BG gets higher than the renal threshold, owner will notice PU/PD - many cats are hyperglycemic for months before this point
T/F: if we can reverse insulin resistance in a cat & manage their BG, the hiding beta cells may start to function again & the cat can be weaned off of insulin
true
what range do we have that supports remission of diabetes mellitus in cats? what factors support remission?
30-80% of cats
aggressive control of BG (keeping it under < 200 mg/dl) supports remission
at-home monitoring lets owner keep tight control & supports remission
what are some clinical signs of diabetes mellitus in cats?
pu/pd/pp & weight loss
cats hover in a pre-clinical state for months, so signs may be less than in dogs
can stumble on a diabetic cat in a routine exam - cat doing well, no signs noticed by owner, & cat has lost some weight
what does it mean if you see diabetic neuropathy in a cat on physical exam?
suggests a long period of hyperglycemia
limits likelihood of remission
what are some examples of causes you should look for on physical exam for a cat with diabetes?
dental/oral disease
chronic skin issues
endocrinopathy - hyperadrenocorticism (pot belly, thin skin), hyperthyroidism (palpable thyroid nodule, heart murmur), or acromegaly (large cat, big feet, prominent mandible, renomegaly)
T/F: cats with diabetes mellitus usually do not develop cataracts
true
T/F: hyperglycemia in a cat = diabetes mellitus
false - rarely goes over 350 mg/dl, lasts for a few hours, & can start at home when the cat sees the carrier
how do you prove persistent hyperglycemia in a cat with diabetes mellitus?
collect urine at home & check BG at home
fructosamine & ketonuria
what changes are seen on biochemistry panels of diabetic cats?
hyperglycemia - bg > 300 mg/dl
hypercholesterolemia & hypertriglyceridemia
+/- minor elevation in ALP (vacuolar change due to lipid mobilization)
what changes are seen in the electrolytes in a diabetic cat?
hyponatremia is common - partially dilution due to hyperglycemia but some increase in urinary loss of sodium
potassium - usually normal in stable DM cats
T/F: measuring serum fructosamine in a cat is a great way to prove sustained hyperglycemia in a diabetic cat
true
why are fructosamine levels great for diagnosing a cat with diabetes mellitus?
fructosamines are a group of proteins (primarily albumin) that become permanently attached to a glucose molecule (glycated)
amount of fructosamines is proportional to BG levels - gives us a look back over the last 2 weeks
amounts of fructosamines are lowered by diseases that impact albumin turnover (hyperthyroidism, gi disease)
why run a total T4 on diabetic cat?
illness will tend to move down T4 in a cat
robust value (high end of reference) should be taken seriously
increased value indicates concurrent hyperthyroidism
how long should you administer insulin to a diabetic cat prior to testing for acromegaly? how do you test for it?
6 weeks - GH levels fluctuate markedly so we measure a surrogate
insulin like growth factor 1 is measured instead - released from the liver in response to GH, levels are more stable, requires insulin to be expressed, so levels are low in untreated diabetics
what are the goals of treatment for a diabetic cat?
- resolve pu/pd
- minimize signs of hypoglycemia
- avoid DKA & peripheral neuropathy
- optimize weight, activity level, & body condition
- satisfied owner
- +/- diabetic remission
what are your two options for first choice insulins for managing diabetic cats?
insulin glargine - U100
protamine zinc insulin - U40
what is the starting dose of insulin glargine for diabetic cats? when is its peak activity (anticipated nadir) anticipated post injection? typical duration?
1 unit/cat twice daily or 0.25 U/kg ideal body weight - BID dosing means the constant presence of insulin which is an ideal way to keep bg below 200 mg/dl all of the time
12-24 hours post injection
lasts 12-24 hours
what is the starting dose of protamine zinc insulin for diabetic cats? when is its peak activity (anticipated nadir) anticipated post injection? typical duration?
1 unit/cat twice daily or 0.25 U/kg of ideal body weight
2-6 hours post injection
lasts 12-24 hours
why is it ideal to give a diabetic cat its first dose of insulin in the hospital?
give dose & check bg every 2 hours
need to identify hypoglycemia - not to determine the perfect dose!!!
stress may impact your reading - don’t increase the dose for the first week
how is diet & body weight managed in diabetic cats?
switch to diabetic diet if possible - carbs provide <14% of metabolizable energy (3 g/100 kcal) - feed twice daily if possible (okay to feed ad lib if cat is not overweight & used to this plan)
aim for gradual weight loss in fat cats - 2% of body weight per week is ideal (0.4 kg/month in a 5 kg cat) - wet food may help improve feelings of fullness
why do you need to get the owner of a diabetic cat on board with at home bg monitoring?
data from cats tested at home is much more reliable - owner can identify decreasing insulin needs if the cat is going into remission!
T/F: an owner may only need to check bg for a curve for the cat if using insulin glargine
true
how often should blood glucose curves be done in newly diagnosed diabetic cats?
every 2 weeks initially & then every 6-8 weeks
T/F: fructosamine levels can be used to assess response to insulin in a stable diabetic cat
true
how is fructosamine used to monitor a diabetic cats response to their insulin dose?
low value indicates periods of hypoglycemia & high value indicates suboptimal regulation
if high, you don’t know why! doesn’t necessarily indicate the need to increase the dose (risky to increase insulin without knowing nadir)
what is blucare?
urine glucose testing for diabetic cats - not yet available in USA
very sensitive test - good way to identify long periods below the renal threshold
why is measurement of water intake an unreliable way of monitoring a diabetic cat?
BG is usually > 250 mg/dl before polydipsia occurs, so the cat is likely to be persistently hyperglycemic
a period of hypoglycemia can be masked by prolonged hyperglycemia (may lead to an inappropriate increase in insulin dose)
what do you do if nadir for a blood glucose curve is < 80 mg/dl in a diabetic cat?
decrease dose by 25-50% - warn owner that cat may be going into remission (insulin needs may drop fast)
what do you do if nadir for a blood glucose curve is 80-250 mg/dl all day in a diabetic cat?
stick to your current dose
what do you do if nadir for a blood glucose curve is > 150 mg/dl in a diabetic cat?
increase dose by 1/2 unit - be sure this isn’t stress induced
cat should be showing signs indicating hyperglycemia - allow several days (at least 3, up to 7) to see effect before increasing again
how should insulin dose adjusting be done if measuring effect by fructosamine levels or water intake in a diabetic cat?
make 1/2 unit changes
T/F: diabetic remission in cats most often occurs within the first 90 days
true
what is the ideal candidate for a cat to achieve diabetic remission?
fat cat who was on a high carb diet that is now on a low carb diet
T/F: addressing dental disease in diabetic cats may help with achieving remission
true
what are some ways that owners may help their diabetic cat achieve remission?
highly motivated owners can try to support remission with intensive monitoring - owners should understand that this can happen quickly & they need to be ready to decrease insulin dose
bg is checked before every insulin dose & approximately 6-8 hours later
goal is to keep bg between 65-220 mg/dl all day
