Diabetes: Practical Insulin Titration (Basal–Bolus & GLP-1 Synergy)
A clinic-ready playbook for outpatient insulin: set targets, start low, titrate on a schedule, fix hypoglycemia fast, and add prandial or GLP-1 agents when basal alone plateaus.
Glycemic Targets (individualize)
- Fasting (pre-breakfast): ~80–130 mg/dL (4.4–7.2 mmol/L)
- Pre-meal (daytime): ~80–130 mg/dL
- 1–2 h post-meal: <180 mg/dL (<10 mmol/L)
- A1C: commonly <7% for many adults; less strict for frail/older or heavy comorbidity
Basal-First Algorithm (Type 2, outpatient)
- Start: 10 units at bedtime or ~0.1–0.2 U/kg/day of a long-acting/basal insulin.
- Titrate: adjust every 3 days using the average of the last 3 fasting readings:
- >180 → +8 units
- 141–180 → +6 units
- 121–140 → +4 units
- 100–120 → +2 units
- 80–99 → no change
- <80 or any nocturnal hypo → −2 to −4 units and reassess bedtime snack/meds
- Basal over-basalization clues: fasting at goal but A1C high; daytime/post-meal highs; basal dose >0.5–0.7 U/kg without improvement → add prandial or GLP-1RA rather than keep increasing basal.
Adding GLP-1 Receptor Agonist (if not already)
GLP-1RAs lower post-prandial glucose, reduce weight, and may cut insulin needs. In many patients, adding GLP-1RA before prandial insulin achieves targets with fewer hypos and less weight gain.
When to Add Prandial (Bolus) Insulin
- Option A – Single “largest meal” dose: start 4 units (or 10% of basal) before the largest meal; titrate by +1–2 units every 2–3 days to keep 1–2 h post-meal <180.
- Option B – Basal-plus → basal-bolus: expand to 2 then 3 meals as needed using the same titration rule.
- Option C – Full carb-counting: initial insulin-to-carb ratio ~1:10–1:15; correction factor ~1800/total daily dose (rapid-acting); tailor to CGM/SMBG data.
Correction Scale (simple outpatient start)
Before meals if pre-meal glucose is above target:
- 150–199 → +1 unit
- 200–249 → +2 units
- 250–299 → +3 units
- ≥300 → +4 units and consider ketone check/sick-day plan
Refine using individual correction factor from CGM/SMBG trends.
Hypoglycemia Prevention & Fixes
- 15-15 rule: if BG <70 mg/dL, take 15 g fast carbs (glucose tabs/juice), recheck in 15 min; repeat until >70; then snack if next meal >1 h away.
- Identify causes: missed meals, extra exercise, alcohol, too much insulin, renal function changes.
- Lower insulin on days with prolonged activity; teach family to use glucagon (nasal or injectable) for severe hypo.
Sick-Day & Safety
- Never stop basal insulin in type 1; in type 2 on insulin, check more often; hydrate; continue correction doses.
- Check ketones if BG ≥300 mg/dL, vomiting, or illness; seek care for persistent ketones or dehydration.
Devices & Technique
- Rotate sites (abdomen, thigh, arm, buttocks); avoid lipohypertrophy.
- Match pen needles to habitus; prime pens; confirm units before dosing.
- CGM improves titration and detects nocturnal hypo; pair with simple written titration plan.
Special Populations
- CKD/elderly: favor conservative targets; smaller titration steps; watch for prolonged insulin action.
- Steroid-induced hyperglycemia: higher post-noon/PM values; consider adding prandial around steroid dosing time or NPH timed to steroid peak.
- Pregnancy: specific targets and regimens—specialist management.
When to Refer/Escalate
- Recurrent severe hypoglycemia, uncertainty about type 1 vs type 2, pregnancy, insulin pump initiation, or persistent A1C above goal despite structured titration.
Patient FAQs
“How fast will my numbers improve?” Most see fasting changes within a week of steady titration; A1C reflects ~3 months of averages.
“Will I gain weight?” GLP-1RA and careful prandial use can limit weight gain; focus on diet quality, protein, and activity.
References & Notes
Practical outpatient approach emphasizing basal-first titration, early GLP-1 consideration, and stepwise prandial addition. Local formularies and protocols vary—follow regional guidance. Educational only.