Related Experiment Video
Updated: May 3, 2026

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes
Published on: June 25, 2017
A novel heterozygous mutation in the glucokinase gene conferring exercise-induced symptomatic hyperglycaemia
M S E Ebrahim1, M L Lawson2, M T Geraghty3
1Division of Endocrinology and Metabolism, Children's Hospital of Eastern Ontario, University of Ottawa, 401 Smyth Road, Ottawa, K1H 8L1, Canada; Department of Pediatrics, Division of Pediatric Endocrinology and Diabetes, Children's Hospital Cairo University, Cairo University, 11562 Cairo, Egypt.
Aim:
To describe the atypical phenotype and genotype of an adolescent girl with symptomatic exercise-induced hyperglycaemia, responsive to sulfonylurea treatment.
Methods:
Chart review, gene sequencing, and blinded continuous glucose monitoring (Medtronic iPro2) were used to characterise the case.
Results:
A novel heterozygous mutation p.Q219x (c.655C>T) in exon 6 of the glucokinase gene (NM_000162.3) was confirmed in the patient and father. Initiation of gliclazide 20mg twice daily was associated with resolution of symptoms and normalization of haemoglobin A1C (5.6%). Blinded continuous glucose monitoring demonstrated significantly less time spent in the hyperglycaemic range (sensor glucose>8.0 mmol/L) when on twice daily gliclazide versus intermittent or no gliclazide (mean minutes/day with sensor glucose > 8 mmol/L: 53.6 ± 90.0 vs. 307.9 ± 246.6; P=0.04).
Conclusions:
This novel mutation in the glucokinase gene led to atypical symptomatic exercise-induced hyperglycaemia that was responsive to low dose sulfonylurea with self-reported additional benefit after reduction of carbohydrate intake. We postulate that her atypical clinical presentation was related to the intense elite-level physical activity combined with carbohydrate loading before exercise.
More Related Videos
08:01Measurement of Insulin- and Contraction-Stimulated Glucose Uptake in Isolated and Incubated Mature Skeletal Muscle from Mice
Published on: May 16, 2021
09:34Targeted Next-generation Sequencing and Bioinformatics Pipeline to Evaluate Genetic Determinants of Constitutional Disease
Published on: April 4, 2018
Related Concept Videos
Glucose Transporters
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
Oral Hypoglycemic Agents: Sulfonylureas
Oral Hypoglycemic Agents: Glinides
Hyperglycemia
Diabetes Mellitus: Type 2 and Gestational
Hypoglycemia and Glucagon