Basal Insulin / Carb Ratio Reference (education) mechanism

Model scope

The arithmetic formula passes dimensional review only under the stated unit and positivity assumptions. Because glucose units, validation constraints, negative-dose behavior, rounding, and the basal-versus-bolus naming issue are not fully specified, the catalog entry needs review before release.

• The formula is standard for an illustrative rapid-acting insulin bolus estimate when carbs are in grams, InsulinCarbRatio is grams per unit, and CorrectionFactor is glucose units per unit of insulin; it does not calculate basal insulin despite the instrument name.
• The specification does not define glucose units. BG, Target, and CorrectionFactor must all use the same scale, such as mg/dL and mg/dL per unit or mmol/L and mmol/L per unit.
• The formula does not specify handling for negative calculated boluses, rounding, minimum doses, or whether a negative correction should be omitted or reduced under clinical instructions.

Units and conventions

• carbs is grams of carbohydrate.
• InsulinCarbRatio is grams of carbohydrate per insulin unit and must be greater than zero.
• Current BG and Target BG use the same glucose unit.
• CorrectionFactor is glucose units per insulin unit and must be greater than zero.
• The resulting Bolus is in insulin units.
• Example glucose values use either mg/dL with mg/dL per unit or mmol/L with mmol/L per unit; the two systems must not be mixed.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "carbs_g": 60,
    "insulin_carb_ratio_g_per_unit": 10,
    "current_bg_mg_per_dL": 180,
    "target_bg_mg_per_dL": 100,
    "correction_factor_mg_per_dL_per_unit": 50
  },
  "expected_outputs": {
    "illustrative_bolus_units": 7.6
  },
  "working": "Carb component = 60 / 10 = 6 units. Correction component = (180 - 100) / 50 = 80 / 50 = 1.6 units. Total = 6 + 1.6 = 7.6 units."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero insulin-to-carbohydrate ratio produces division by zero and an undefined bolus. The instrument should reject this input explicitly; returning a numeric result would be a safety-relevant failure of input validation.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json