What lies beneath: a case of spontaneous hypoglycaemia or glucose transporter type 1 defect disguised as chronic fatigue? (2013) Mohit Kumar et al.

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This is an interesting case study (bolding and spacing added);

What lies beneath: a case of spontaneous hypoglycaemia or glucose transporter type 1 defect disguised as chronic fatigue?

A 42-year-old female had extensive neurological investigations (normal MRI brain, EEG, NCS). A low CSF glucose triggered endocrine referral.

She had a history of ill health/fatigue since 19 years when she had a viral illness with seizure-like episode and transient wheelchair dependance, with no formal diagnosis made. She had recurrent symptoms including fatigue, myalgia and weakness, with some relation to hunger and fasting.

The history and examination is characteristic of the paroxysmal late-onset form of glucose transporter type one (GLUT 1) deficiency syndrome. This is usually caused by mutations in the SLC2A1 gene and results in impaired glucose transport into the brain.

Patients develop classical features of hypoglycaemia with normal peripheral blood glucose. Some marginal changes may occur in serum lactate (i.e. inappropriately low <1 mmol/l) when symptomatic. Lower limb pain and jerking is characteristic.

Ketogenic diet is effective in 60% of cases. This is an autosomal dominant condition and is likely to be under-diagnosed. Cases may appear in endocrine clinics because of hypoglycaemic symptoms and hunger. Symptoms may be assumed to be functional or related to chronic fatigue syndrome.

https://www.endocrine-abstracts.org/ea/0031/ea0031p235.htm