Hypoglycemia

Question 1

What are the most common causes of hypoglycemia in DM individuals?

Answer 1

DM: Most commonly due to insulin/sulphonylurea Rx (AEx).

• GASTRO: Missed/delayed/inadequate meal; malabsorption; gastroparesis due to autonomic neuropathy –> variable carb absorption.
• ENDO: other unrecognised endo disorder e.g. Addison’s
• LIFE: Unexpected or unusual exercise; Alcohol; Poorly designed insulin regiment (esp if predisposing to nocturnal hyperinsulinemia)
• OTHER: Lipohypertrophy at injection sites –> variable insulin absorption; breastfeeding

Question 2

What are the criteria for diagnosing a hypoglycaemic disorder in a non DM individual?

Answer 2

Not uncommon to detect venous BGL below 3.0mmol/L in asymptomatic non-DM individual hence ONLY diagnose when all 3 conditions of Whipple’s triad are met: i) patient had symptoms of hypoglycemia ii) low BGL measured at time of symptoms iii) symptoms correct on correction of hypoglycemia

Question 3

Symptoms of hypoglycemia in non-DM?

Answer 3

Patients often have hypoglycemia unawareness: may present with symptoms of neuro-glycopenia (convulsions, odd behaviour). Symptoms episodic and often resolve on eating carb meal.

Question 4

What symptoms are more indicative of pathological hypoglycemia?

Answer 4

Symptoms occurring while fasting (eg before breakfast) or after exercise.

Question 5

Ix in acute presentation of hypoglycemia?

Answer 5

1) Test BGL at bedside 2) Collect sample for later testing of: alcohol, insulin, C-peptide, cortisol, and sulphonylurea levels.

Question 6

Ix in O/P presentation of episodic hypoglcyemia?

Answer 6

72 hour fast. If symptoms develop > collect sample > give glucose. Symptoms resolve on glucose administration completing Whipple’s triad.

Question 7

Causes of hypoglycemia in non-DM individuals?

Answer 7

Non-DM: alcohol excess other drugs (e.g. quinine, salicylates, pentamidine) hepatic or renal failure sepsis malaria

Question 8

What does hypoglycemia in the absence of insulin/insulin-like factor indicate?

Answer 8

Disorder of gluconeogenesis and or impaired availability of glycogen from the liver.

Question 9

Most likely Dx adult with high insulin and C-peptide concentrations?

Answer 9

Insulinoma (but also consider sulphonylurea ingestion - particularly in people with access)

Question 10

How are insulinomas detected?

Answer 10

CT, MRI or ultrasound (endoscopic or laparoscopic).

Question 11

Why should the liver also be imaged in insulinoma investigations?

Answer 11

10% insulinomas are malignant.

Question 12

How might a non-pancreatic tumour cause hypoglycemia?

Answer 12

Rarely, large non-pancreatic tumours (e.g. sarcoma) may cause recurrent hypoglycemia because of the ability to produce pro-insulin-like growth factor 2 (pro-IGF-2).

Question 13

Management mild (self treated) hypoglycemia?

Answer 13

Oral fast-acting carbohydrate (10 - 15g) taken as glucose drink or tablets or confectionary.

Follow with snack containing complex carbs.

Question 14

Management in hypoglycemia due to sulphonylurea poisoning?

Answer 14

IV dextrose infusion.

Question 15

What is the role of intramuscular glucagon? When is it ineffective?

Answer 15

Stimulates hepatic glucose release. Ineffective in patients with depleted glucose reserves (e.g. alcohol excess or liver disease).

Question 16

What is hypoglycemia?

Answer 16

BGL <3.5mmol/L

Question 17

What are the 3 primary physiological mechanisms to correct low BGL (in healthy people)?

Answer 17

1. endogenous insulin release from pancreatic B cells is reduced
2. release of glucagon from pancreatic alpha cells is increased
3. autonomic nervous system activated with catecholamine release

Question 18

What is the overall effect of the physiological response to hypoglycemia?

Answer 18

Reduce whole body glucose uptake and increase hepatic glucose release (to maintain glucose supply to the brain).

Question 19

What are the symptoms of hypoglycemia?

Answer 19

Can be divided into autonomic and neuroglycopenic:

Autonomic: sweating, trembling, pounding heart, hunger, anxiety.

Neuroglycopenic: confusion, drowsiness, difficulty speaking, inability to concentrate, incoordination, irritability/anger.

Question 20

What are the RFx for severe hypoglycemia?

Answer 20

• Strict glycaemic control
• Impaired awareness of hypoglycemia
• Age (very young/elderly
• Long duration of diabetes
• Sleep
• C-peptide negativity (i.e. complete insulin deficiency)
• Hx of previous severe hypoglycemia
• Renal impairment
• Genetic e.g. ACE genotype

Question 21

Management in severe (external help required) hypoglycemia?

Answer 21

If patient unconscious/semi conscious: parenteral Rx required.

IV 75mL dextrose (=15g; give 0.2g/kg in children)

OR

IM glucagon 1mg (0.5mg in children)