Current guidance
The most current ADA guidance is the 2026 Standards of Care. Insulin dosing must be individualized by diabetes type, weight, diet, kidney/liver function, HbA1c, pregnancy status, risk of hypoglycaemia, current regimen, and whether the person is eating. A single fasting blood sugar (FBS) value is not enough to safely calculate a one-time insulin dose for everyone.
For most non-pregnant adults, the usual fasting/pre-meal target is
80-130 mg/dL (4.4-7.2 mmol/L). Targets should be less strict in frail older adults or those at high hypoglycaemia risk.
ADA 2026 glycaemic treatment guidance
1. Starting basal insulin in stable outpatient Type 2 diabetes
Basal insulin controls glucose overnight and between meals, so it is adjusted using the pattern of fasting readings, not a single FBS.
Common starting approach:
- 0.1-0.2 units/kg once daily, or
- a simple fixed start such as 10 units once daily, often at the same time each day.
ADA 2026 supports a starting basal dose of
0.1-0.2 units/kg/day, with individual titration.
ADA insulin recommendations
Example clinician-approved basal titration plan
Use the average of the last 3 fasting readings:
| Average FBS | Basal dose action |
|---|
| <70 mg/dL (<3.9 mmol/L), or symptomatic hypoglycaemia | Reduce basal insulin, commonly by 10-20% or 2-4 units, and contact clinician |
| 70-79 mg/dL | Consider a small reduction if recurrent, especially if overnight symptoms occur |
| 80-130 mg/dL | Maintain the dose |
| >130 mg/dL with no hypoglycaemia | Increase by 2 units every 3 days, or 1 unit daily, until target is reached |
| Persistently >180 mg/dL | Assess adherence, injection technique, illness, food intake, and need for clinician review rather than escalating indefinitely |
One published primary-care protocol used 10 units nightly, then adjusted by the 3-day average: <80 mg/dL: reduce 3 units; 80-110: no change; >110: increase 3 units. This is an example protocol, not a universal prescription. Textbook of Family Medicine, 9e, p. 981.
Do not keep increasing basal insulin if FBS is already at target but HbA1c remains high. This usually indicates post-meal hyperglycaemia and needs review of meals, non-insulin medicines, or addition of meal-time treatment rather than more basal insulin. ADA calls this concern
overbasalization.
ADA 2026 guidance
2. Meal-time or correction insulin: do not dose from FBS alone
Rapid-acting insulin before a meal is determined by:
- Current pre-meal glucose
- Carbohydrate to be eaten
- The patient's prescribed insulin-to-carbohydrate ratio
- Their correction factor or insulin-sensitivity factor
- Active insulin from a recent dose
- Whether they will actually eat
A commonly used correction-factor estimate for people already using rapid-acting insulin is:
Insulin sensitivity factor (ISF) = 1800 ÷ total daily insulin dose
This estimates how much 1 unit of rapid-acting insulin may lower glucose, in mg/dL.
Example only: if total daily dose is 45 units:
- ISF = 1800 ÷ 45 = 40 mg/dL per unit
- If prescribed target = 120 mg/dL and pre-meal glucose = 200 mg/dL:
- correction estimate = (200 - 120) ÷ 40 = 2 units
This calculation must be built into an individualized written plan. It is not appropriate for insulin-naive patients, missed meals, vomiting/poor intake, pregnancy, advanced kidney disease, frailty, recurrent hypoglycaemia, or suspected diabetic ketoacidosis.
3. Inpatient patients
For hospitalized non-critically ill patients who are eating, current ADA guidance generally prefers:
- Basal + nutritional/prandial + correction insulin, not correction-only or "sliding scale" insulin as the sole regimen.
- Correction insulin commonly begins when glucose is approximately 140-150 mg/dL, but the exact scale must be approved locally and matched to insulin sensitivity, nutritional intake, renal function, and prior insulin use.
Do not use an outpatient FBS titration scheme for acutely ill, fasting/NPO, postoperative, septic, steroid-treated, or unstable patients. Those situations require a hospital protocol and frequent capillary glucose monitoring. The 2026 ADA hospital guidance notes correctional dosing generally starts at 140 or 150 mg/dL.
ADA hospital care standards
4. Safe insulin administration checklist
Before giving insulin, verify:
- Correct patient, insulin type, concentration, dose, route, and timing
- Current capillary glucose/CGM reading
- Last insulin dose and whether rapid-acting insulin is still active
- Meal availability and expected carbohydrate intake for prandial insulin
- Hypoglycaemia symptoms and previous low readings
- Renal function, acute illness, steroid treatment, and changes in oral intake
- Insulin is not expired, incorrectly stored, or cloudy when it should be clear
- Injection site is intact and rotated: abdomen, thigh, or upper arm; avoid lipohypertrophy
For rapid-acting insulin, administer immediately before meals or according to the product and local policy. Hold meal insulin if the meal is not available, unless there is a specific medical order. Basal insulin often should continue even when not eating, especially in Type 1 diabetes, but dose modification must be prescribed.
5. Hypoglycaemia safety
Treat glucose <70 mg/dL (3.9 mmol/L) promptly:
- If conscious and able to swallow: give 15 g fast-acting carbohydrate, recheck in 15 minutes, and repeat if still low.
- If unconscious, having seizure, unable to swallow, or severely unwell: urgent emergency treatment with glucagon or IV dextrose by trained staff.
Patients with Type 1 diabetes must not have basal insulin stopped completely, because this can precipitate diabetic ketoacidosis.
Key practical point
For a stable Type 2 diabetic newly starting basal insulin, use a prescribed basal dose and adjust it based on a 3-day fasting glucose trend, usually in small 1-3 unit increments. Do not give a universal "X units for this FBS" dose. If you tell me whether this is for an outpatient or inpatient patient, Type 1 or Type 2 diabetes, current insulin regimen, weight, kidney function, and FBS pattern, I can help interpret the guideline-based approach more specifically.