C-Peptide to Glucose Ratio
Fasting C-peptide to fasting glucose ratio helps distinguish type 1 from type 2 diabetes and assesses residual beta-cell function. Low ratio suggests type 1 or insulin deficiency; high ratio suggests type 2 or insulin resistance.
Score interpretation
C-peptide:glucose ratio <0.2 — likely beta-cell failure; type 1 diabetes probable
→ Check fasting C-peptide, GAD65, IA2, ZnT8 antibodies; confirm type 1 diabetes; insulin therapy required; refer to diabetes clinic for insulin regime; screen for associated autoimmune conditions (thyroid, coeliac, Addison's)
C-peptide:glucose ratio 0.2–0.5 — borderline; consider MODY or late-onset T1DM (LADA)
→ Check GAD antibodies; if GAD-positive = LADA (latent autoimmune diabetes of adults); if GAD-negative = consider MODY (HNF-1α, HNF-4α, glucokinase) — refer for genetic testing; management depends on classification
C-peptide:glucose ratio ≥0.5 — adequate beta-cell function; type 2 diabetes likely
→ Confirm type 2 diabetes; lifestyle modification; metformin first-line; consider GLP-1RA or SGLT-2 inhibitors based on cardiovascular/renal profile; annual HbA1c and diabetes review
Interpretation bands for the C-Peptide Ratio. Apply clinical judgement and local guidance.
References
- Hattersley AT, Patel KA. Precision diabetes: learning from monogenic diabetes. Diabetologia. 2017;60(5):769–777.
Related
Curated clinical cross-links plus same-class fallbacks.
- Tirzepatide · Dual GIP/GLP-1 Receptor Agonist — Type 2 Diabetes / Obesity
- Noradrenaline (Norepinephrine) · Vasopressor (Alpha-1 and Beta-1 Agonist)
- Dobutamine (ICU — Inotrope) · Inotrope (Beta-1 Agonist)
- Insulin (IV Infusion — ICU Glucose Control) · Insulin — ICU Glucose Management
- Labetalol (IV — Hypertensive Emergency) · Combined Alpha-1 and Beta-Adrenergic Blocker
- Ephedrine hydrochloride · Mixed alpha/beta-adrenergic agonist (vasopressor)
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022
- Hyperthyroidism Management · BTA / ETA 2018
- Adrenal Insufficiency · Society of Endocrinology / ESE 2016
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.