Glycaemia

Glycaemia refers to the concentration of glucose in the blood. It is a key indicator of energy availability for the body's tissues and is influenced by dietary intake, hepatic glucose production, and the rate at which glucose is utilized by organs such as the brain, liver, muscle, and adipose tissue. Maintaining glycaemia within a narrow range is essential for metabolic stability.

Measurement of glycaemia is commonly expressed in millimoles per litre (mmol/L) in many countries, with milligrams per decilitre (mg/dL) used in others. Fasting plasma glucose is typically about 3.9–5.5 mmol/L (70–99 mg/dL) in a healthy person. After meals, blood glucose rises and usually falls toward baseline within two to six hours. Normal postprandial levels are generally below 7.8 mmol/L (140 mg/dL) at two hours in individuals without diabetes. Persistent dysglycaemia, whether high or low, indicates an abnormal glycaemic state.

Regulation of glycaemia mainly involves insulin and glucagon, produced by the pancreatic islets, with additional modulation by hormones such as cortisol, epinephrine, and incretins. After eating, insulin promotes glucose uptake and suppresses hepatic glucose production; during fasting, glucagon stimulates glucose release from the liver.

Clinical significance includes diabetes mellitus, characterized by chronic hyperglycaemia and associated complications, and hypoglycaemia, a dangerous drop in blood glucose risk especially with glucose-lowering therapies. Monitoring and management aim to keep glycaemia within individual targets using diet, physical activity, and medication, including insulin when required. Glycaemia is also assessed through continuous glucose monitoring and time-in-range metrics in contemporary care.