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MODY 2 (GCK-MODY)

Glucokinase mutation causing mild stable hyperglycemia

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 2 (GCK-MODY)?

Glucokinase serves as the pancreatic beta cell glucose sensor, regulating insulin secretion in response to plasma glucose.

Heterozygous loss-of-function GCK mutations raise the glucose set-point so insulin is secreted at higher glucose levels but otherwise normally.

GCK-MODY accounts for 10–60 percent of MODY cases depending on population.

Inheritance is autosomal dominant with very high penetrance — fasting hyperglycemia is detectable from birth.

It is critically important to distinguish from type 1 or type 2 diabetes because pharmacotherapy is generally unnecessary and ineffective.

Symptoms

Stable mild fasting hyperglycemia (typically 5.5–8 mmol/L)
HbA1c usually 5.6–7.6 percent throughout life
Asymptomatic in most patients — discovered on routine screening or during pregnancy
Limited rise in postprandial glucose (typically less than 3 mmol/L increment)
Absence of microvascular or macrovascular complications even after decades
Normal lipid profile and normal fasting C-peptide

Risk Factors

Heterozygous mutation in the GCK gene (autosomal dominant inheritance)
Family history of mild lifelong hyperglycemia or 'gestational diabetes that never resolved'
Multiple family members across generations diagnosed with diabetes at very young age but not requiring insulin
Negative islet autoantibodies (distinguishes from type 1)
Lean body habitus without metabolic syndrome (helps distinguish from type 2)

When to See a Doctor?

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

  • Childhood or adolescent diagnosis of mild diabetes without typical type 1 or type 2 features
  • Persistent mild hyperglycemia detected during pregnancy with strong family history
  • Multiple affected family members with diabetes diagnosed under age 25
  • Diabetes that fails to progress despite years without treatment
  • Negative autoantibodies and preserved C-peptide in a young patient

Treatment Methods

01
Genetic confirmation by GCK sequencing — definitive and changes management
02
No pharmacotherapy required outside of pregnancy in the great majority of patients
03
Healthy lifestyle counseling but strict glucose control offers no proven benefit
04
In pregnancy: only treat if fetus does not carry the mutation (suggested by ultrasound growth above 75th percentile by 26–28 weeks)
05
If treatment indicated in pregnancy, insulin is preferred
06
Reassurance about extremely low risk of microvascular complications
07
Cascade genetic testing of first-degree relatives

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.