Hypoglycemia

Hypoglycemia, also spelled hypoglycemia, is the medical term for an abnormally low blood glucose level (too low a concentration of glucose in the blood).

Although blood glucose thresholds are difficult to define due to interindividual differences, the current literature defines blood glucose levels below 50-60 mg/dl (2.77-3.3 mmol/l) as hypoglycaemia even without other symptoms, and even below 70 mg/dl (3.9 mmol/l) if there are noticeable symptoms.

A distinction is made between hypoglycaemia without symptoms ("asymptomatic hypoglycaemia") and hypoglycaemia with symptoms ("symptomatic hypoglycaemia"). In the latter case, a distinction is made between two degrees of severity, one being whether the affected person can still help himself or whether he is dependent on outside help. Depending on the duration and severity of the condition, classic symptoms include sweating, clouding of consciousness, delirium and even coma (hypoglycaemic coma, colloquially known as sugar shock or diabetic shock). Untreated severe and persistent hypoglycemia can be fatal. It must not be confused with diabetic coma (coma diabeticum), a severe metabolic derailment with hyperglycaemia.

Certain cells of the human body, such as brain cells, depend on a continuous supply of energy in the form of glucose. In hypoglycaemia, the sugar content of the blood drops to such an extent that the cells' ability to function is impaired. Therefore, in metabolically healthy individuals, the first compensatory mechanisms occur at levels below about 60 mg/dl, the aim of which is to increase the blood glucose level again. These compensatory mechanisms prevent threatening hypoglycaemia even during prolonged periods of starvation. The cause of hypoglycaemia is usually a relative excess of the blood sugar-lowering hormone insulin in the blood, or an overdose of blood sugar-lowering drugs, such as certain antidiabetic drugs, which overtaxes the physiological compensation mechanisms. The cause of such hyperinsulinemia is usually an overdose of an insulin injection as part of the treatment of diabetes mellitus. In very rare cases, insulin-producing tumours (insulinomas) can also be the cause.

Therapy of hypoglycemia consists of oral administration of glucose. In a medical emergency or if the patient cannot swallow, glucose must be administered intravenously. Glucagon can also be administered intramuscularly or subcutaneously to increase blood glucose in an emergency. In the long term, stabilisation of blood glucose levels by improving insulin therapy or eliminating other causes (for example, removal of an insulinoma) is indicated.

Introduction

A common definition of hypoglycemia from 1983 describes a blood glucose level below 40 mg/dl without symptoms or 50 mg/dl with symptoms. The blood glucose level at which symptoms occur varies from individual to individual. The rapid lowering of an elevated blood glucose level also promotes their occurrence. Therefore, in more modern definitions, hypoglycemia is further classified clinically into four levels from mild to moderate to severe and severe with medical intervention.

Distribution

Hypoglycaemia is of quantitative importance, particularly in drug-treated diabetics. For example, of the type 2 diabetics treated with sulfonylureas in the UK, it is estimated that more than 5000 patients per year experience severe hypoglycemia with emergency hospitalization. The cost of hospitalisation for severe hypoglycaemia in the UK is estimated at £1000 per case.

There may also be an association between repeated episodes of severe hypoglycaemia and the development of dementia. One episode of severe hypoglycemia increased the risk of developing dementia by 26 percent (HR, 1.26; 95% CI, 1.10-1.49), two by 80 percent (HR, 1.80; 95% CI, 1.37-2.36), and three or more episodes by almost double (HR, 1.94%; 95% CI, 1.42-2.64) in the patients observed after chart review.

Infantile hypoglycemia after delivery is the quantitatively most significant complication following maternal diabetic metabolism during pregnancy.