Beta-cell function in individuals carrying the mitochondrial tRNA leu (UUR) mutation
João Eduardo Salles1, Teresa S Kasamatsu, Sérgio A Dib
1Division of Endocrinology, Department of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil.
Pancreas
|January 2, 2007
Summary
Individuals with the mitochondrial DNA A3243G mutation show impaired insulin secretion, contributing to diabetes development. Coenzyme Q10 may improve beta-cell function in some patients.
Area of Science:
- Genetics and Metabolism
- Endocrinology
- Mitochondrial Diseases
Background:
- The mitochondrial DNA A3243G mutation is associated with various clinical manifestations, including diabetes mellitus.
- Beta-cell dysfunction is a key factor in the pathogenesis of type 2 diabetes.
- Understanding the impact of specific genetic mutations on beta-cell function is crucial for developing targeted therapies.
Purpose of the Study:
- To evaluate beta-cell function in individuals with the mitochondrial DNA A3243G mutation, comparing those with normal glucose tolerance (NGT) to those with diabetes mellitus (DM).
- To investigate the effect of coenzyme Q10 supplementation on insulin secretory response in diabetic individuals with the A3243G mutation.
Main Methods:
- Study included eight mutation-positive individuals (four NGT, four DM).
- Beta-cell function assessed via C-peptide levels (fasting and post-meal Sustacal challenge) and first-phase insulin response.
- Diabetic patients received 3-month coenzyme Q10 supplementation to evaluate its impact.
Main Results:
- Diabetic patients exhibited significantly lower C-peptide levels compared to controls (P=0.001).
- Beta-cell function was preserved in NGT individuals (P=0.87).
- Diabetes duration negatively correlated with fasting C-peptide (r=-0.961, P=0.038). Coenzyme Q10 improved C-peptide in 2/3 patients with residual secretion. First-phase insulin response was diminished in the oldest NGT individuals.
Conclusions:
- The A3243G mutation is associated with impaired insulin secretory capacity, potentially a primary defect leading to DM.
- The observed beta-cell defect appears to be functional.
- Coenzyme Q10 shows potential for improving beta-cell function in select patients.
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