Abstract
This guideline systematically reviews the evidence for the investigation of adult hypoglycaemia. Causes of hypoglycaemia in non-diabetic patients can be deduced by careful review of the history, clinical examination, routine laboratory tests and medication history. This may elucidate causes including sepsis, hepatic, cardiac, adrenal or renal failure, alcohol, antihyperglycaemic agents and other drugs.
In seemingly-well patients hypoglycaemia is defined as a plasma glucose concentration <3 mmol/L. Under these conditions, samples should be collected for glucose, insulin, c-peptide, proinsulin, β-hydroxybutyrate, insulin antibodies and oral hypoglycaemic agents. If insulin (>18 pmol/L), c-peptide (>0.2 nmol/L) and proinsulin (>5.0 pmol/L) are increased, insulinoma should be suspected. If insulinoma is not located via imaging, the patient may have the rare disorder noninsulinoma pancreatogenous hypoglycaemia syndrome (NIPHS), which can present with a similar biochemical picture. This is due to islet cell hypertrophy and can be a consequence of Roux-en Y gastric bypass. Patients with NIPHS often suffer from postprandial hypoglycaemia, and should be assessed after a mixed meal and not after an oral glucose tolerance test. Insulin autoimmune hypoglycaemia is a rare disorder and seems to occur primarily in persons of Japanese or Korean origin. Patients often have a history of autoimmune disease or exposure to sulphydryl-containing drugs. Hypoglycaemia occurs late in the postprandial stage due to uncontrolled release of insulin. Diagnosis is readily made by a high titre of serum insulin antibodies. It is also essential that accidental, surreptitious and malicious hypoglycaemia are excluded.
The investigation of patients with both hypoglycaemia and diabetes is essential. Hypoglycaemia is often under-reported: patients with type 1 diabetes may have one to two symptomatic hypoglycaemic attacks per week and one severe temporarily disabling episode a year. Patients with drug-treated diabetes should become concerned about declining diabetic control at a plasma glucose concentration of <3.9 mmol/L, to account for the inaccuracies of glucose meters and to allow the patient time to take preventive action.
The guideline provides a useful overview of the causes, investigation and treatment in the often difficult to diagnose presentation of hypoglycaemia in the adult.