Fasted Treadmill, New Insulin, Rotating Shifts
Ms. Okafor is 47, newly diagnosed with type 2 diabetes (HbA1c 8.9%), BMI 33, taking metformin 1000 mg twice daily and starting insulin glargine 10 units at bedtime this week. She works rotating shifts (two days, two nights, four off) as a hospital porter and has bilateral knee osteoarthritis. She wants to lose 15 kg before her daughter's wedding in five months and has begun skipping breakfast and doing 60-minute fasted treadmill sessions at 7.0 METs six days a week. She reports two episodes of shakiness and sweating during these sessions in the past ten days, both resolving after juice. Her fasting glucose log ranges 4.2–11.8 mmol/L. She has not seen a dietitian and asks whether she should stop the metformin to speed weight loss.
1. Which parts of her current routine are unsafe or counterproductive, and why?
Read the worked answer
The fasted 7.0 MET sessions are the priority problem. Three factors stack:
- Insulin initiation. Starting basal insulin raises hypoglycemia risk, and the risk is highest when exercise is unaccustomed, prolonged, or performed without recent carbohydrate.
- Fasting before exercise. Her liver glycogen is low and there is no exogenous glucose, so a 60-minute session at 7 METs is exactly the scenario for a symptomatic low.
- She has already had two episodes of shakiness and sweating that resolved with juice. Those are presumed hypoglycemia until proven otherwise, and a third episode could occur while driving home.
7.0 METs is likely well above her tolerable intensity. At BMI 33 with knee osteoarthritis and a sedentary baseline, that is near-maximal work, not moderate. It also drives knee pain and makes adherence fragile.
Six days of 60 minutes is a dose she cannot sustain, and starting at maximum removes any room to progress. Skipping breakfast while on insulin also worsens glycemic variability and tends to increase later-day intake rather than improve weight.
Her 15 kg target works out to roughly 0.75 kg per week - achievable but only with nutrition support she does not yet have.
Nothing here is a reason to stop exercising. It is a reason to restructure the timing, dose, and fuelling before week one ends.
2. Rewrite the aerobic and resistance prescription for weeks 1–4, with intensity anchors, fuelling rules, and stop criteria.
Read the worked answer
Aerobic - build duration before intensity.
- Frequency: 3–5 days/week, and on shift days a 10-minute walk is enough to count.
- Intensity: RPE 11–13 or the talk test (can speak in sentences but not sing). Target heart rate is unreliable on metoprolol-free but shift-variable days; use RPE as the primary anchor.
- Time: start at 15–20 minutes continuous, add 5 minutes every week toward 30–45 minutes, building to 150 minutes/week total.
- Mode: walking, cycle ergometer, or pool - low impact for the knees. Avoid stair-heavy work on night shifts.
Resistance - 2 non-consecutive days/week. 8 exercises covering legs, hips, back, chest, shoulders, arms, core. 1–2 sets of 10–15 at RPE 12–14, full range, no breath holding. Include quadriceps and hip work for the knees; expect temporary soreness, not joint swelling.
Fuelling and monitoring rules.
- Check glucose before exercise. If under 5.5 mmol/L, eat 15–30 g carbohydrate first and wait.
- Carry 15 g fast carbohydrate (juice boxes, glucose tablets) in a pocket, not in a locker.
- Avoid exercising within 2 hours of a rapid-acting insulin dose; rotate injection sites away from limbs being exercised.
- Recheck glucose after the first several sessions, at bedtime on training days, and any time she feels shaky - late hypoglycemia can occur hours after exercise.
- Stop the session for shakiness, sweating, confusion, or glucose under 4.0 mmol/L; treat and do not resume that day.
- Daily visual foot check for blisters or redness.
3. How do you answer her metformin question, and which referrals do you initiate?
Read the worked answer
Answer her directly but stay inside your scope. Say plainly: "I can't advise you to stop or change a medication - that's your prescriber's call, and I'd be guessing if I said otherwise. What I can tell you is that metformin on its own rarely causes low blood sugar; the lows you've described line up much better with fasting plus long, hard sessions right after starting insulin. Stopping metformin wouldn't make your training safer, and it could push your glucose the wrong way. Please raise it with your diabetes team, and if you want, I'll put the question in writing so it isn't lost in a short appointment."
Do not suggest dose changes, do not imply the insulin is unnecessary, and do not let her leave thinking you endorsed stopping anything.
Referrals and coordination:
- Dietitian and diabetes education program - she has no nutrition support, is on insulin, and is fasting around exercise. This is the single highest-yield referral.
- Prescriber - for hypoglycemia review, glucose monitoring frequency, and sick-day/shift-work planning, with her consent.
- Physiotherapy or physician for the knee osteoarthritis if pain limits walking.
- Foot screening by a clinician, since she has diabetes and reduced sensation has not been assessed.
Send a brief note to each, with consent, stating what you observed, what program she is on, and what you are asking them to address. Document the consent, the referrals, and the medication conversation verbatim in substance.