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MODY 3 (HNF1A-MODY)

Most common monogenic diabetes responsive to sulfonylureas

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is MODY 3 (HNF1A-MODY)?

HNF1A encodes a transcription factor critical for normal beta cell development and insulin secretion.

Heterozygous HNF1A mutations cause progressive beta cell dysfunction with onset typically before age 25.

HNF1A-MODY accounts for 30–65 percent of MODY cases — the most frequent monogenic diabetes subtype.

Inheritance is autosomal dominant with very high penetrance: 63 percent develop diabetes by age 25 and over 95 percent by age 55.

Patients have a notable response to sulfonylureas; many can be transitioned from insulin to oral therapy.

Symptoms

Progressive hyperglycemia presenting in adolescence or young adulthood
Marked postprandial glucose excursions while fasting glucose may be near-normal initially
Low renal threshold for glucose causing glycosuria at near-normal blood glucose
Absence of obesity or other features of metabolic syndrome
Microvascular complications (retinopathy, nephropathy) develop similarly to type 1/type 2 diabetes if untreated
Striking response to small doses of sulfonylureas (sometimes hypoglycemia at standard doses)

Risk Factors

Heterozygous HNF1A mutation (autosomal dominant inheritance)
Strong family history with diabetes in multiple generations diagnosed before age 25
Negative islet autoantibodies
Preserved C-peptide years after diagnosis (uncommon for type 1 diabetes)
Lean body habitus and absence of insulin resistance features

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Diabetes diagnosed before age 25 in a non-obese patient with strong family history
  • Antibody-negative diabetes responding poorly to typical type 2 therapy
  • Persistent C-peptide secretion years after diagnosis
  • Diabetic family members spanning multiple generations with early-onset disease
  • Glycosuria at relatively low blood glucose levels

Treatment Methods

01
Genetic confirmation by HNF1A sequencing — changes management substantially
02
First-line treatment: low-dose sulfonylureas (e.g., gliclazide 20–40 mg/day) — often dramatic glycemic improvement
03
Many patients on insulin can be successfully transferred to sulfonylurea monotherapy
04
Add prandial insulin or GLP-1 agonist if hyperglycemia progresses despite optimized sulfonylurea
05
Standard diabetes complication screening: annual retinal, renal, foot and lipid assessments
06
Cardiovascular risk management identical to other diabetes forms
07
Cascade genetic testing of first-degree relatives — predictive testing identifies at-risk individuals before disease onset

Which Department to Visit?

You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.