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Michaelmas 5th year > Hypoglycaemia and diabetes mellitus > Flashcards

Hypoglycaemia and diabetes mellitus Flashcards

1
Q

What hormones can elevate glucose levels

A

Glucagon = main one
Also adrenaline, norepinephrine
Cortisol, growth hormone

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2
Q

What glucose levels trigger insulin release from pancreatic beta cells

A

> 6mmol/L

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3
Q

What things stimulate vs inhibit glucagon release

A

Stimulate: hypoglycaemia, adrenaline
Inhibition: insulin, somatostatin

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4
Q

What toxin can cause hypoglycaemia

A

Xylitol causes hypersecretion of insulin

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5
Q

Hypoglycaemia associated tumours

A
  • Pancreatic e.g insulinoma
  • Extra-pancreatic e.g hepatocellular carcinoma, others
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6
Q

Different aetiologies of hypoglycaemia

A

Inadequate intake via diet
Excessive uptake of glucose by normal or neoplastic cells
Impaired hepatic gluconeogenesis/glycogenolysis e.g in liver disease
Deficiency in diabetogenic hormones e.g hypocortisolaemia

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7
Q

What signs does the catecholamine surge cause in hypoglycaemia

A

Hunger
Muscle fasciculations
Nervousness
Restless ness

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8
Q

Emergency treatment of hypoglycaemia

A

GLucose/dextrose IV
If failing to respond to that give dexamethasone (steroids) iV

If neither available can do glucagon injection pen

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9
Q

Where to insulinomas metastasise to

A

Liver, local LNs, omentum

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10
Q

What is the most common cause of significant hypoglycaemia in dogs

A

Insulinoma

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11
Q

How do we siagnose an insulinoma

A

Clinical signs
Hypoglycaemia (<3.3mmol/L) or hypoglycaemic after fasting and measuring in hospital
ACCOMPANIED BY normal or high serum insulin

CT/MRI

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12
Q

What medical management can we use for insulinomas

A

Prednisolone
Diazoxide to inhibit beta cell insulin production and enhance liver glycogenolysis and gluconeogenesis

Can try chemo

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13
Q

Why might surgery for insulinoma lead to diabetes mellitus (temporarily)

A

Due to a post-surgical pancreatitis

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14
Q

What type of diabetes mellitus do dogs tend to get

A

Type 1 i.e insulin dependent

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15
Q

What type of diabetes mellitus do cats tend to get

A

Type 2 i.e insulin indepedent

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16
Q

What are the possible causes of diabetes in dogs

A

Main one = immune-mediated islet destruction
Also hormonal antagonism: entire females in dioestrus, hyperadrenocorticism
Pancreatitis; due to fibrosis/necrosis damage
Rarely congenital disese

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17
Q

How can hyperadrenocorticism cause diabetes in dogs

A

Via cortisol antagonising insulin

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18
Q

How does dioeutrs in entire females cause/exacerbate diabetes mellitus

A

Because progesterone induces growth hormone secretion from mammary tissue whcih then antagonises insulin

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19
Q

What are some hallmarks of diabetes mellitus in cats

A

Insulin resistance
Loss of beta cell function

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20
Q

How do cats lose beta cell function in DM

A

Apoptosis following chronic hyperfunction secondary to insulin resistance
Islet amyloid deposition
Glucose toxicity causing structural damage and irreversible beta cell loss

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21
Q

What is glucose toxicity

A

When peripheral glucose is high for a long period and causesdamage to cells

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22
Q

Cats having transient diabetes mellitus

A

~20% of diabetic cats
Islets can return to normal via aggressive treatment e.g weight loss to prevent insulin resistance

Then go into a subclinical diabetic state

23
Q

At what glucose level do we see clinical signs of hyperglycaemia

A

When it exceeds the renal threshold
i,e 12-16mmol/L
This is the value of blood glucose at which the proximal renal tubule can’t reabsorb the filtered glucose so it passes out of the urine, dragging water with it (osmotic idiuresis) and causing PU/PD

24
Q

Ket 4 clinical signs of diabetes mellitus

A

Polyuria
Polydipsia
Polyphagia
Weight loss

25
Q

What other signs apart from main 4 might be seen in DM

A

Concurrent infections e.g UTI
Peripheral neuropathy in cats
Cataracts in dogs

26
Q

How does peripheral neuropathy present in DM cats

A

See in ~10% of chronically hyperglycaemic cats
Femoral nerve commonly affected; see this as a plantigrade stance (loss of extensor tone)

27
Q

Diagnosing diabetes mellitus

A

Hyperglycaemia above renal threshold
Glucosuria on urinalysis

+ other find hypercholesterolaemia, increased ALP and ALT

28
Q

What can we use to work out if high glucose is from diabetes mellitus or stress in cats

A

Measure fructosamine; this is irreversibly glycosylated albumin that reflects glucose levels in preceding 1-2 weeks

29
Q

How can stress affect glucose levels in cats

A

Can increase them significantly i.e >20-30mmol/L

30
Q

What type of insulin in caninsulin

A

Lente insulin i.e intermediate acting
= pig insulin
Dogs and cats both best on twice daily

31
Q

What type of insulin is PZI

A

Longer acting than lente; recombinant human insulin
Dogs stable on once daily; cats stil need twice

32
Q

What type of insulin is glargine

A

Slow release long acting
NB: not licensed
Has micrcrystals that release insulin from subcut depot injection site

33
Q

What is an oral hypoglycaemic agent that may be used in cats

A

Glipizide; e.g if cannot inject cats

34
Q

What is the ideal diet for a DM dog

A

low sugar, increased fibre, low fat

35
Q

What is the ideal diet in DM cat

A

key is low carbohydrate
High protein
Don’t need high fibre

36
Q

why is food/insulin timing in cats less important than dogs

A

Because their post-prandial hyperglycaemia lasts up to 24 hrs compared to 6 hours in dogs

37
Q

5 causes of instability in diabetes patient

A

Practical factors e.g poor dosing/storage/injection
Insulin induced hyperglycaemia (smogyi overswing)
Infection/inflammation
Hormonal antagonism
Inadequate insulin activity e.g poor absorption due to scar tissue, anti-insulin antibodies

38
Q

What is the smogyi overswing

A

Where too high doses of insulin are given to a diabetic causing hypoglycaemia
This leads to release of counterregulatory hormones i.e glucagon and cortisol and get rebond hyperglycaemia which can last days

Get cyclic history of a few days good control then poor control

39
Q

What factors can lead to smogyi overswing

A

Owners changing the doses of insulin

Cats having lost weight so now the dose is too high

If concurrent inflammation/infection has been treated so now the insulin requirement is lower

40
Q

Which animals might fructosamine be a poor way of assessing glucose control

A

Those with increased protein turnover e.g hyperthyroid cats

41
Q

Why must we do a cysto and culture urine after diagnosing DM

A

Because UTI is common and <5% of dogs with this alongside DM show clinical signs

42
Q

Hormonal antagonism of insulin causing unstable diabetes

A

Hyperadrenocorticism; these would be on very high doses and still uncontrolled
Exogenous glucocorticoids for another condition
Hypothyroidism
Excess growth hormone i.e acromegaly
Entire females in dioestrus; high progesterone stimulates GH release from mammary tissue + direct progestagen antagonism of insulin

43
Q

What might we. doif suspecting anti-insulin antibodies are preventing treatment for DM from working

A

Switch to homologous preparation

44
Q

What happens in diabetic ketoacidosis

A

Ketone body formation in liver
Metablic acidosis
Severe dehydration
Shock death
Relates to insulin deficiency and excess of counter-regulatory hormones e.g glucagon due to concurrent disease e.g UTI, pancreatitis, renal failure, steroid adminitsration, dioestrus phase, neoplasia

45
Q

Biochemistry signs with diabetic ketoacidosis

A

Hyperglycaemia significant
Ketonaemia
Azotaemia
Metabolic acidosis
Elevated liver enzymes
Electrolyte abnormalities esp low K+

46
Q

Clinical signs of diabetic ketoacidosis

A

lethargy, depression, weakness, dehydration, vomiting, tachypnoea (in response to metabolic acidosis)

47
Q

Managing DKA

A

Fluids
Insulin; short acting for fine control
Carbohydrate substrates
Control vimiting and nausea
Identify precipitating disease e.g UTI

48
Q

Signs of hypokalaemia

A

muscle weakness including cervical ventroflexion in cats, vomiting, diarrhoea, cardiac arrhythmias, cardiac arrest

49
Q

Signs of hypophosphataemia

A

haemolytic anaemia, muscle weakness, seizures, stupor, coma [cats more sensitive]

50
Q

Why do we supplement K+ and phosphate before treating cats in DKA

A

Already low levels usually

+ fluid dilute them out and get excretion
Insulin drives them both into cells so causes blood concentration to fall

51
Q

What do we do with blood sample to test for glucose

A

Either separate quickly to remove cells (stop them using up the glucose)
Or place in fluoride oxalate tube

52
Q

What would we expect the urine glucose test to be like in a well controlled diabetic

A

Will still have trace glucose
If glucose pad is -ve this suggests overdosing with insulin

53
Q
A

Michaelmas 5th year (41 decks)

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