Table 2 Main causes of hypoglycaemia related to inborn errors of metabolism (IEM) in adults

Glycogenolysis disorders

I: high blood lactates especially before meals, hypertriglyceridaemia, hyperuricaemia

Glycogen Storage Disease

Ketones rather low

Liver:

I, VI, IX, 0, Fanconi-Bickel

III: high blood lactates especially after meals, hypertriglyceridaemia,

I, III, 0, Fanconi-Bickel

Ketones rather high

Mixed:

III, IV

III (debranching enzyme or amylo-1,6-glucosidase enzyme)

GSD I/III: DNA (leucocytes)

Defect of fatty acid oxidation

- no ketones (or rather low during hypoglycaemia)

- carnitine cycle (CPT1/2)

- CPT1

- high free carnitine plasma level (CPT1)

- ß fatty acid oxidation

- VLCAD, MCAD, SCHAD, LCHAD

- accumulation of plasma acylcarnitines (example : High C8 and high C8/C2 ratio in MCAD)

- electron transfer

- ketogenesis

- HMG-CoA lyase

MCAD

- urine organic acid accumulation

- ß oxidation in vitro (lymphocytes)

- DNA (leucocytes)

Gluconeogenesis

Fructose-1,6-biphosphatase

Fructose-1,6-biphosphatase

- lactic acidosis

- high alanine

- ketosis

- high glycerol

- urine: high 3 Ph glycerol

NIPHS (sometimes in fasting period)

- hypoglycaemia during infancy (SUR.1, Kir6.2, SCHAD, GDH, Glucokinase

- Glucokinase mutation

- hyperinsulinism

- sometimes progression to diabetes in adulthood (especially SUR-1)

- hyperammonemia (GDH) - Genotyping (DNA leucocytes)

CDG Ia, Ib, Id (sometimes at anytime)

- CDG Id

no

Isoelectric focussing of transferrin

- phosphomannomutase gene (Ia)

- phosphomannomutase isomerase gene (Ib)

- 1,3-mannosyltransferase (Id)

Hyperinsulinism

Inherited fructose intolerance

- After ingestion of fructose (fruits, sucrose, sweet foods)

- fructose test tolerance iv

- Late postprandial period

- breath test fructose

- DNA leucocytes : aldolase B gene

NIPHS

- MCT1

yes

Genotyping (DNA leucocytes)