Hyperglycemia

Hyperglycemia
Other names	High blood sugar, hyperglycemia, hyperglycæmia
Artist's depiction of hyperglycemia. White hexagons in the image represent glucose molecules, which are increased in the lower image.
Specialty	Endocrinology

Hyperglycemia or hyperglycaemia is the situation in which blood glucose level is higher than in a healthy subject. A fasting healthy human shows blood glucose level up to 5.6 mmol/L (100 mg/dL). After a meal (postprandial) containing carbohydrates, healthy subjects show postpandrial euglycemic peaks of less than 140 mg/dL (7.8 mmol/L).^{[1][2][3][4][5][6][7]} Therefore, fasting hyperglycemia are values of blood glucose higher than 5.6 mmol/L (100 mg/dL) whereas postprandial hyperglycemia are values higher than 140 mg/dL (7.8 mmol/L).^[2][3] Postprandial hyperglycemic levels as high as 155 mg/dL (8.6 mmol/L) at 1-h are associated with T2DM-related complications, which worsen as the degree of hyperglycemia increases.^{[8][9][10][11]} Patients with diabetes are oriented to avoid exceeding the recommended postprandial threshold of 160 mg/dL (8.89 mmol/L) for optimal glycemic control.^[12][11][13] Values of blood glucose higher than 160 mg/dL are classified as ‘very high’ hyperglycemia,^[1] a condition in which an excessive amount of glucose (glucotoxicity) circulates in the blood plasma. These values are higher than the renal threshold of 180 mg/dL (10 mmol/L) up to which glucose reabsorption is preserved at physiological rates^[8][14][15] and insulin therapy is not necessary.^[16][17] Blood glucose values higher than the cutoff level of 200 mg/dL (11.1 mmol/L) are used to diagnose T2DM^[18] and strongly associated with metabolic disturbances,^[19] although symptoms may not start to become noticeable until even higher values such as 13.9–16.7 mmol/L (~250–300 mg/dL). A subject with a consistent fasting blood glucose range between ~5.6 and ~7 mmol/L (100–126 mg/dL) (American Diabetes Association guidelines) is considered slightly hyperglycemic, and above 7 mmol/L (126 mg/dL) is generally held to have diabetes. For diabetics, glucose levels that are considered to be too hyperglycemic can vary from person to person, mainly due to the person's renal threshold of glucose and overall glucose tolerance. On average, however, chronic levels above 10–12 mmol/L (180–216 mg/dL) can produce noticeable organ damage over time.