Dose for long-acting insulin depends on weight, glucose patterns, and prescriber guidance; a common adult start is 0.1–0.2 units/kg once daily.
Finding a safe, steady dose of a background insulin is a step-by-step task. The goal is simple: wake up with steady readings and fewer swings during the day. This guide walks through how clinicians commonly start and adjust a basal dose, what numbers to watch, and when to change course. It’s practical, plain, and based on widely used standards.
How To Estimate Your Long-Acting Insulin Dose
For adults with type 2 diabetes who are new to insulin, many teams begin with a small daily amount tied to body weight. Two evidence-based choices are used: a flat 10-unit start or a weight-based start at 0.1–0.2 units per kilogram. The weight-based route often fits when fasting readings are well above target; the flat start is handy when readings sit just over goal.
The table below shows the math at common body weights. These are starting estimates only. Your prescriber may adapt the plan for age, kidney or liver conditions, past lows, or other medicines.
| Weight (kg) | 0.1 u/kg Start | 0.2 u/kg Start |
|---|---|---|
| 50 | 5 units | 10 units |
| 60 | 6 units | 12 units |
| 70 | 7 units | 14 units |
| 80 | 8 units | 16 units |
| 90 | 9 units | 18 units |
| 100 | 10 units | 20 units |
| 110 | 11 units | 22 units |
| 120 | 12 units | 24 units |
What “Basal” Means And Why It Matters
Basal insulin covers the glucose your liver releases between meals and overnight. It’s not meant to cover food. When the background dose fits, fasting readings sit near target without frequent lows, and daytime swings are easier to manage with meal plans and other medicines.
Targets To Aim For With Background Insulin
Most adult care plans aim for fasting plasma glucose in the 80–130 mg/dL range, with two-hour post-meal numbers under 180 mg/dL. Your team may set a higher range if there’s a history of lows, frailty, or complex health needs. Pick a single fasting target with your prescriber and titrate to it.
Step-By-Step Titration Plan
Daily Routine
Take the basal dose at the same time each day. Check fasting glucose each morning under similar conditions. Log doses and readings. Consistency speeds up safe titration.
Simple Up-Titration
Increase by 2 units every 3 days until fasting reaches your agreed target without lows. Some programs use 1 unit daily or 2–4 units once or twice per week. Pick one rule and stick with it for at least two weeks before judging results, unless there are lows.
When To Hold Or Reduce
If glucose drops under 70 mg/dL, or if there’s an unexplained low at night, cut the basal dose by 10–20% and review recent food intake, activity, and alcohol. Re-check targets with your prescriber before re-titrating.
Special Dose Notes By Diabetes Type
Type 2 Diabetes
When tablets and injectables no longer hold fasting numbers in range, a once-daily basal can be added. Many labels for glargine products guide a start near 0.2 units/kg or up to 10 units once daily. Real-world titration then brings fasting toward target.
Type 1 Diabetes
Total daily insulin for adults often lands in the 0.4–1.0 units/kg range, split between background and mealtime doses. Basal makes up about 40–50% of that total, with the rest given at meals or for corrections. Dose splits change with growth, weight change, exercise, or pump settings.
Brand Differences That Matter
Long-acting options include glargine U-100, glargine U-300, degludec U-100 or U-200, and detemir. Each has its own label rules, action curve, and pen design. Glargine U-300 and degludec last longer and may need a slightly different titration rhythm. Stay with one product during titration to avoid confusion.
Safety First: Who Should Start Lower
A cautious start is wise for older adults, people with kidney or liver disease, those with recent severe lows, and anyone with food insecurity or erratic schedules. In these settings, many teams begin at 0.1 units/kg or the flat 10-unit start, then move slowly with close follow-up.
When Basal Alone Is Not Enough
If fasting readings are on target but A1C stays above goal, the background dose might be high already. Look for “over-basal” signals: dose above 0.5 units/kg, bedtime–morning drop over 50 mg/dL, or frequent daytime snacks to treat dips. At that point, add meal-time doses or a GLP-1 RA per plan, rather than pushing basal higher.
Common Pitfalls And Fixes
Skipping Doses
Missing a daily shot leads to morning highs and daytime swings. Set a phone alarm or use a pen with memory.
Stacking Changes
Changing dose every day muddies the picture. Use one titration rule. Review a full week of data before the next change unless there’s a low.
Chasing Bedtime Readings
Basal targets the morning number. If bedtime is high from dinner, a correction or meal plan change is safer than a big basal bump.
How Labels And Guidelines Line Up
Most product labels give clear starts and cautions. Glargine products often say 0.2 units/kg or up to 10 units once daily for adults with type 2 diabetes who are new to insulin, and about one-third of total daily insulin for adults with type 1 diabetes. Professional standards echo a 10-unit or 0.1–0.2 units/kg starting range with small, steady increases. See the ADA Standards of Care and the Lantus prescribing information for labeled starting guidance.
| Product | Concentration | Common Start Guidance |
|---|---|---|
| Insulin glargine (U-100) | 100 units/mL | Adults with type 2: 0.2 u/kg or up to 10 u daily; type 1: about one-third of total daily insulin |
| Insulin glargine (U-300) | 300 units/mL | Adults with type 2: about 0.2 u/kg daily; type 1: one-third to one-half of total daily insulin |
| Insulin degludec | 100 or 200 u/mL | Adults with type 2: fixed or weight-based starts with slow titration per fasting target |
| Insulin detemir | 100 units/mL | Once or twice daily based on response; weight-based starts used in practice |
Practical Titration Example
Say a 90-kg adult is starting therapy. A 0.1 u/kg start gives 9 units daily. Morning readings stay near 170 mg/dL after three days. Increase to 11 units and review readings after another three days. If a morning low occurs, drop by 2 units and call the clinic. Keep meal patterns steady during this period so changes reflect the insulin, not the menu.
When To Call The Clinic
- Any reading under 54 mg/dL
- Two or more lows under 70 mg/dL in a week
- Persistent morning numbers above target for two weeks despite stepwise increases
- Sick days, steroid use, or major diet or activity changes
- Pregnancy or plans to conceive
Safe Technique And Timing
Pick one time of day and stick with it; evening is common for many glargine and degludec products. Rotate sites across the abdomen, thighs, or buttocks to reduce lipohypertrophy. Use a fresh needle each time. Store pen or vial as the label directs.
Data To Bring To Each Visit
- Seven to fourteen days of fasting readings
- Dose changes with dates
- Any lows, with time of day and possible cause
- Current non-insulin medicines
- Average daily steps or activity notes
Quick Dose Recap
For adults starting background insulin in type 2 diabetes, a small daily dose tied to body weight or a flat 10-unit start is common, then careful titration toward a clear fasting target. For adults with type 1 diabetes, total daily insulin is weight-based, with the background share near 40–50% of the total. In all cases, move in small steps, check daily, and ask for help fast if readings drop too low.
This guide shares general education, not personal medical advice. Always set your dose plan with your own care team.