Diabetes – complications

The chronic micro- and macrovascular complications of diabetes. For the acute emergencies (DKA and HHS), see DKA & HHS.

Diabetes causes both macrovascular and microvascular complications, but microvascular disease is specific to diabetes. Give special attention to the “deadly quartet” of type 2 diabetes with obesity, hypertension and dyslipidaemia. People with type 1 diabetes still have a significantly reduced life expectancy, mainly from diabetic nephropathy and vascular disease (MI, stroke).

Consider the organs affected under the mnemonic KNIVES — Kidney, Nerves, Infection, Vessels, Eyes, Skin.

Macrovascular disease

Ischaemic/coronary heart disease, cerebrovascular disease and peripheral vascular disease. In the HOPE study, ramipril in type 2 diabetes reduced death (24%), MI (22%), stroke (33%), cardiovascular death (37%) and overt nephropathy (24%). Cardiovascular risk-factor management (BP, lipids, smoking, weight) is central — see Type 2 Diabetes Management.

Microvascular disease

The small vessels most affected clinically are the retina, nerve sheath and kidney glomerulus. In younger patients it typically takes 10–20 years from diagnosis for retinopathy, neuropathy and nephropathy to manifest.

Nephropathy

Prevention is an essential goal. The earliest marker is microalbuminuria — screen with a first-morning urine albumin/creatinine ratio (dipstick is unreliable; 24-hour collection is impractical in general practice). Early disease can be slowed/reversed with optimal glycaemic and, particularly, blood pressure control.

Retinopathy and maculopathy

Consequence of retinal microvascular disease; prevalence relates to disease duration, but up to 20% of people with type 2 already have retinopathy at diagnosis. Diabetes is a leading cause of blindness in working-age adults. Annual expert fundoscopy (dilated ophthalmoscopy, retinal photography, or fluorescein angiography as needed) is recommended; early laser photocoagulation delays/prevents visual loss.

Neuropathy

• Sensory polyneuropathy (glove-and-stocking) — the commonest
• Mononeuropathy / mononeuritis multiplex — e.g. median nerve, cranial III/VI palsies, diabetic amyotrophy; radiculoplexus neuropathy
• Autonomic — erectile dysfunction, postural hypotension/syncope, gastroparesis, diabetic diarrhoea, neurogenic bladder, silent ischaemia, hypoglycaemia unawareness, and sudden cardiac arrest under anaesthesia

Infections

Poorly-controlled diabetes predisposes to: skin infections (mucocutaneous candidiasis — balanitis, vulvovaginitis; staphylococcal folliculitis); urinary tract infections (cystitis, pyelonephritis, perinephric abscess); and respiratory infections (staphylococcal/pneumococcal pneumonia, tuberculosis).

Other complications

Cataracts and refractive error; obstructive sleep apnoea; depression; musculoskeletal disease (Charcot neuroarthropathy, tendon rupture); and neuropathic foot ulcers. Acute metabolic complications — hypoglycaemia, diabetic ketoacidosis, hyperosmolar hyperglycaemic state and lactic acidosis — are covered on the DKA & HHS page.