Anna Liachenko, BSc, MSc

People with diabetes mellitus can have both acute and chronic complications from their disease. This article focuses on Hyperglycemic Hyperosmolar Non-Ketotic Syndrome (HHNS) and hypoglycemia, which are two important acute complications that occur in elderly diabetics.

Hyperglycemia
The key problem with diabetes is abnormal metabolism of carbohydrates leading to hyperglycemia. Blood glucose levels between 8 mmol/L and 10 mmol/L are sufficient to cause tissue damage but can be present in some patients without clinical symptoms for many years. This increases the risk of developing multiple long-term complications such as retinopathy, nephropathy and neuropathy.

During the life of a diabetic person, various factors may acutely raise hyperglycemia to symptomatic levels. These include high carbohydrate foods, stress, illness (usually infection), and medications (e.g. glucocorticoids, nicotinic acid, diuretics and phenytoin). If blood sugar rises above 10 mmol/L, it exceeds the renal reabsorption threshold and causes osmotic diuresis, resulting in loss of water and electrolytes (mainly sodium, potassium, phosphorus and magnesium). This creates a cycle of progressive hyperglycemia potentially having acute life-threatening consequences: diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar non-ketotic syndrome (HHNS). DKA occurs primarily in patients with Type 1 diabetes which tends to occur in younger patients.