Fasting blood glucose level higher than 126 mg/dl or 7.0 mmol/l is labeled as hyperglycemia.
Fasting hyperglycaemia may occur in the following conditions:
1. Diabetes mellitus:
– Absence or insensitivity to insulin, leading to impaired glucose tolerance and hyperglycemia
2. Pancreatic disorders
a. Pancreatectomy :
– e.g.: trauma (road traffic accidents,penetrating abdominal injuries), Surgical removal of pancreas (for pancreatic tumor).
b. Haemochromatosis :
– Deposition of iron in islets cells within pancreas and destroying islet cells.
c. Chronic pancreatitis :
– Chronic inflammation of pancreas resulting in fibrosis & irreversible destruction of pancreatic parenchyma, e.g: Alcohol abuse, longstanding pancreatic duct obstruction.
d. Carcinoma of pancreas :
– Glucagonoma which is the tumour of Islet cells
3. Endocrine disorders
a. Cushing’s syndrome :
– Glucocorticoids will induce gluconeogenesis and inhibit glucose uptake by tissues causing hyperglycemia.
b. Acromegaly :
– Excessive secretion of Growth hormone causes increased gluconeogenesis
c. Thyrotoxicosis :
– Causes hyperglycemia by inducing glycogenolysis in liver,also increases the basal metabolic processes (activity/rates).
d. Phaeochromocytoma :
– Tumour of adrenal medulla causing hyperglycemia by secretion of catecholamines(epinephrine,norepinephrine),that cause gluconeogenesis.
Increased cortisol and adrenaline secretion leading to gluconeogenesis:
- cerebrovascular accidents
- myocardial infarction (MI)
1. IV glucose infusions
– Salicylates (analgesics)
– Oral contraceptives(steroid preparation)
– Steroids (used as antiallergic, anti inflammatory, replacement therapy for steroid deficiency)
In MI stress, hyperglycaemia is fairly common. However, recent investigations indicate that many of these patients have diabetes mellitus (especially if the plasma glucose exceeds 10 mmol/L); thus, all stress hyperglycaemia patients should be investigated at a later date for possible diabetes mellitus.