An HbA1c of 9.4% and a 50% Refill Record
A 62-year-old man with type 2 diabetes attends a pharmacist-led review. HbA1c is 9.4% (up from 8.6% six months ago). Metformin 1000 mg twice daily was prescribed 6 months ago; the dispensing record shows he has filled only two 90-tablet bottles in that period. Today he tells you, "My sugar pills cost $38 each time and I have to choose between them and my blood pressure pills sometimes. I don't really understand why I take two a day." He works night shifts, eats one large meal after work, and reports no hypoglycemia. BP is 148/88 mmHg, BMI 31 kg/m2, eGFR 82 mL/min/1.73 m2. He lives alone and does not drive.
1. Quantify his adherence using the available data and explain what the number does and does not tell you.
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- Calculate proportion of days covered (PDC): the observation window is 6 months = about 180 days. Metformin 1000 mg twice daily requires 2 tablets/day, so 180 days needs 360 tablets. He received 2 × 90 = 180 tablets, which covers 180 ÷ 2 = 90 days.
- PDC = 90 ÷ 180 = 0.50, i.e., 50%. (A medication possession ratio calculated as fills ÷ expected refills gives 2 ÷ 6 = 33%, but PDC is the more standard metric because it accounts for quantity dispensed and overlaps.)
- What it tells you: he is missing roughly half his expected exposure, which is more than enough to explain a rising HbA1c; adherence should be addressed before adding a second or third agent.
- What it does not tell you: PDC is a proxy based on fills, not ingestion. It cannot distinguish "did not fill" from "filled but took half the tablets to make the supply last longer" - and his own statement suggests the latter. It also says nothing about timing, food, or persistence over a longer horizon.
- Be explicit about the implication: escalating therapy on the assumption of full adherence would be a dosing error by proxy. Ask him directly, non-judgmentally, how many tablets he actually takes in a day.
2. Identify the barriers in this case using a structured framework, and prioritize them.
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- Cost/access: a $38 copay competing with antihypertensive medication costs is a concrete financial barrier - the single most actionable item. Options include generic metformin (already generic) from a lower-cost pharmacy, a 90-day supply to reduce dispensing fees, checking formulary/trillium or provincial low-income drug programs, and asking whether the antihypertensives can be synchronized to one dispensing date to reduce combined fees.
- Health literacy/understanding: "I don't really understand why I take two a day" signals a knowledge gap about dose, purpose, and the asymptomatic nature of diabetes. He may be interpreting "two a day" as an error or excess.
- Regimen fit with lifestyle: night shifts mean his largest meal is post-shift, and twice-daily dosing around a shift schedule is easy to lose. Ask exactly when he takes each dose relative to sleep.
- Behavioural/social: living alone, no driving (transport to pharmacy and to lab appointments is a real constraint), possible low mood or diabetes distress - screen briefly.
- Prioritize: cost first (concrete, solvable, and likely the dominant driver), then understanding, then regimen fit. Address the HbA1c only after these are settled.
3. Describe the conversation and the concrete action plan you would use at this visit, and what you would measure to judge success.
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- Conversation (motivational interviewing, not lecturing): open-ended question - "Tell me how the metformin fits into your day." Reflect back the cost dilemma and affirm that prioritizing blood pressure medication is a rational choice under pressure. Use teach-back: ask him to explain in his own words why two tablets a day, and when he would take them. Avoid shaming; missed doses are information, not a character flaw.
- Concrete actions:
- Resolve the cost: check the lowest-cost dispensing option, 90-day fills, fee synchronization, and any provincial/industry patient assistance program; involve the prescriber if a switch is needed.
- Simplify: confirm with the prescriber whether metformin extended-release 2000 mg once daily with the evening meal is suitable - one tablet, one time, matching his post-shift meal and roughly halving pill burden.
- Anchor the dose to his routine (with the meal after his shift) and link it to an existing habit.
- Give a written, plain-language plan and a pill organizer or phone alarm if he wants one.
- Book a short follow-up in 2–4 weeks rather than 3 months; brief, frequent contact improves persistence early.
- Address BP separately (148/88) rather than bundling everything into one overwhelming visit.
- Measures of success: PDC at the next refill interval (target >80%), a repeat HbA1c in 3 months (a 1–1.5% fall is plausible with restored adherence alone), a pill count or self-report at follow-up, and patient-reported confidence on a 0–10 scale. Document the cost barrier and the plan in the record so the next clinician does not restart at the same assumption.