Diabetic Complications and Emergencies – By Dr. Gnana Sankaralingam
Diabetes is a multi-system disorder affecting several parts of the body. It is a result of either body unable to produce adequate insulin or body not able to utilise available Insulin. Diabetes is a syndrome characterised by chronic high blood sugar (hyperglycaemia). High level of glucose in blood produces osmotic diuresis leading to increased urinary output (polyuria) and thirst (polydypsia). It also causes increased carbohydrate craving (polyphagia) and despite it, there is weight loss. Diabetes is classified into insulin dependant (IDDM) and non-insulin dependant (NIDDM). IDDM has acute onset in youth, where Insulin treatment is mandatory, while NIDDM is of insidious onset usually in middle aged related to obesity, but older patients may be non-obese. Other rare causes are secondary to pancreatic disease or steroid induced. Those of impaired glucose tolerance may progress to diabetes.
Complications of diabetes is categorised into macro-vascular (involving large blood vessels) and micro-vascular (involving small blood vessels). Large vessel problems are seen in arteries of brain, heart and limbs, while small vessel problems are seen in arteries of eyes, kidneys and nerves. In the brain carotid and cerebral arteies are affected, which could result in strokes and transient ischemic attacks (mini-strokes). In the heart coronary arteries are affected, which could lead to angina and heart attacks. Type 2 diabetes (NIDDM) is often associated with hypertension (high blood pressure) and hyperlipidaemias (high cholesterol), and this cluster predispose to cardio-vascular disease. Uncontrolled diabetes makes patient susceptible to sepsis such as skin abscess, cellulitis and genital fungal infections.
Mainly lower limbs are affected by diabetes, involving large and small blood vessels. Large vessel involvement manifests as aches in calf during walking which is relieved by rest (intermittent claudication) which is similar to stable angina of heart. This progresses to pain during rest, similar to unstable angina of heart. Small vessels are affected in the feet and toes which causes pain at rest or elevating the lower limb. Both progress to gangrene of the affected part which is similar to heart attack. These parts will be pale at first and turning into bluish discolouration, numb to touch, cold in temperature and loss of movement, which necessitate amputation. Circulation blockage also contribute to foot ulceration.
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Eye problems in diabetes are cataracts, glaucoma and retinopathy (affecting retina the light sensitive membranes at back of eyes). Cataract is due to opacification of lens which is treated by extracting the lens and replacing an artificial implant. Glaucoma is due to increased pressure within the globe, which if untreated can damage the optic disc leading to blindness. It is initaially treated with eye drops to reduce pressure. Open angled glaucoma is where fluid (aqueous humour) in the eye does not drain properly raising pressure within the eye, which is relieved by trabaculectomy, surgically or using laser. In closed angle galucomas iris blocks the drainage angle, and when is completely blocked presents with painful and red eye with appearnce of halos, which becomes an emergency, relieved by iridotomy surgically or using laser. Retinopathy may be background with micro-aneurysms and hard exudates or proliferative with cotton wool exudates and new vessel formation, which has to be followed in clinic. Retinal detachment where fluid collects between retina and optic nerve cutting off vision and vitreous haemorrhages (bleeding into globe) are acute emergencies.
Kidneys are affected in diabetes (Nephropathy) by micro-vascular damage to glomerulus (urine filtering mechanism). First indication of it is, presence of micro-albumin in the urine. Normally there should not be any protien or sugar in the filtrate. Sugar if present, may be due to diabetes, renal glycosuria or alimentary glycosuria. Vigorous reduction of risk of progression of problem is by treating with angiostensin coverting enzyme (ACE) inhibitor. Chronic kidney dease (CKD) is managed conservatively, but acute kidney injury need urgent intervention. Indications for dialysis are persistently raised potassium level, low bicarbonate level (acidosis) despite treatment, accumulation of fluid in brain (cerebral oedema) causing fits, in lungs (pulmonary oedema) causing difficulty in breathing, in the space between heart and its overlap (pericardium) causing cardiac tamponade (prevent it beating effectively) and in abdominal cavity (ascites). Extreme cases of kidney failure may progress to uraemic coma and acidosis. Renal transplant as last resort improves life dramatically in many.
Nerves are affected in diabetes by micro-vascular damage and altered neural metabolism. Narrowing of blood vessels cause ischemia and damage to nerve fibres (axons). Patients present with paraesthesia (“pins and needles”), numbness or reduced sensation to pain, which could result in injuries and ulcers and muscle wasting especially in thigh muscles of lower limb (adductors and quadriceps). Foot ulcer may be due to presence of neuropathy (involvement of nerves) and peripheral vascular disease superceded by infection. Thickening of skin (callous formation) cause tissue necrosis beneath it, which eventually breaks through to the surface. Regular check of feet for detecting any abnormality is necessary. Autonomic (involuntary nervous) effects of diabetes are postural hypotension, overflow incontinenece, nocturnal diarrhoea, difficulty in swallowing, faulty heart beats and impotence.
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Metabolic emergencies in diabetes are hypoglycaemic (low sugar) coma, the most commonest seen in those using insulin and in those on long acting anti-diabetic drugs, which presents with profused sweating, blackout and cold extremities, which is treated with intravenous glucose. Next common is keto-acedotic (DKA) coma, where when the patient is unable to metabolise sugar due to lack of insulin, body resorts to burning fats as a resource for energy supply. In the process the end products are fatty acids (ketones) which is toxic to the brain resulting in coma. Large sugar content in blood causes osmotic diuresis in kidneys leading to loss of water and dehydration. Treatment is to correct dehydration with normal saline drips and bring sugar level down by Insulin infusion on a sliding scale. Those who are ill can develop hyperosmolar non-ketoacedotic coma, where the viscosity of blood is raised but there are no ketones. These are treated with half normal saline to correct dehydration and insulin to bring sugar level down and in addition given heparin to prevent clots forming. Fourth type of coma is lactic acidosis which is rare and difficult to manage, seen especially in those on metformin as well as in sepsis and kidney failure causing high level of urea. In any cases of coma, securing airway is very important to prevent choking and death.
