PEBC MCQ study guide: Endocrine & Metabolic Disorders

Providing Care – Clinical Care

Type 2 diabetes pharmacotherapy, thyroid disease, and obesity management.

Type 2 Diabetes — Pharmacotherapy Algorithm

Metformin remains first-line for essentially all patients with type 2 diabetes, titrated to a maximum tolerated dose (usually 2000 mg/day in divided doses), contraindicated at eGFR <30 mL/min/1.73m² (use with caution/reduced dose 30–45).

The second agent is chosen by compelling comorbidity, not simply by A1C alone — this is the single most heavily tested diabetes concept:

Established cardiovascular disease → SGLT2 inhibitor or GLP-1 receptor agonist with proven CV benefit (empagliflozin, canagliflozin, dapagliflozin; liraglutide, semaglutide, dulaglutide)
Heart failure → SGLT2 inhibitor preferred
CKD/albuminuria → SGLT2 inhibitor preferred (renal-protective independent of glycemic effect)
Need for weight loss → GLP-1 receptor agonist (most potent) or SGLT2 inhibitor
Cost/access-limited, no compelling comorbidity → sulfonylurea or DPP-4 inhibitor may be reasonable, though these lack the CV/renal protective data of the above

Insulin is added when A1C remains significantly above target despite oral/injectable combination therapy, or at diagnosis if markedly symptomatic/very high A1C (basal insulin, e.g. glargine, is the usual starting insulin in T2DM).

Class-specific pearls:

SGLT2 inhibitors: risk of genital mycotic infections, euglycemic DKA (hold during acute illness/surgery — "sick day" rules), volume depletion; contraindicated in T1DM
GLP-1 RAs: GI side effects (nausea, most common reason for discontinuation), contraindicated with personal/family history of medullary thyroid carcinoma or MEN2
Metformin: B12 deficiency with long-term use, lactic acidosis risk in renal impairment (hold before iodinated contrast in patients with reduced renal function)
Sulfonylureas: hypoglycemia and weight gain — glyburide carries the highest hypoglycemia risk of the class and is generally avoided in the elderly

Thyroid Disorders

Hypothyroidism: levothyroxine is first-line, dosed by weight (~1.6 mcg/kg/day in most adults, lower starting doses in the elderly or those with cardiac disease). Take on an empty stomach, 30–60 minutes before breakfast, separated from calcium, iron, and PPIs by at least 4 hours (all reduce absorption). TSH is rechecked no sooner than 6 weeks after a dose change, since it lags the free T4 change.

Hyperthyroidism (Graves' disease most common cause): methimazole is first-line (preferred over propylthiouracil except in the first trimester of pregnancy and thyroid storm, where PTU is favoured). Both carry a rare but serious agranulocytosis risk — counsel patients to report sore throat/fever immediately. Beta-blockers (propranolol) manage adrenergic symptoms (tachycardia, tremor) while definitive therapy takes effect.

Obesity Pharmacotherapy

GLP-1/GIP receptor agonists (semaglutide, liraglutide, and the dual GIP/GLP-1 agonist tirzepatide) are now the most effective pharmacotherapy for chronic weight management, used alongside lifestyle intervention. Obesity Canada's guideline frames obesity as a chronic disease requiring long-term management, not a short-course intervention — medications are generally continued indefinitely, as weight regain is common on discontinuation.

Orlistat (lipase inhibitor, reduces fat absorption) is an older, less commonly used option, with GI side effects (steatorrhea) that limit tolerability.

High-yield points

Metformin first-line for nearly everyone; the SECOND diabetes drug is chosen by compelling comorbidity (CV disease, HF, CKD → SGLT2i/GLP-1 RA), not by A1C alone.
SGLT2 inhibitors: hold on sick days (euglycemic DKA risk), watch for genital mycotic infections.
Levothyroxine: empty stomach, separate from calcium/iron/PPI by 4 hours; recheck TSH no sooner than 6 weeks post dose-change.
Methimazole preferred over PTU except first-trimester pregnancy/thyroid storm — both need agranulocytosis counseling.

Guideline references

Diabetes Canada Clinical Practice Guidelines
Choosing Wisely Canada — Thyroid Testing
Obesity Canada Clinical Practice Guideline