26th June 2023

Diabetes and the kidney

Complications of diabetes

Diabetes accounts for almost 1 in 7 deaths in the UK, and whilst the majority of these are from cardiovascular complications, diabetes is the most common cause of chronic kidney disease in the UK and the developed world.

Chronic complications of diabetes are usually categorised as microvascular or macrovascular depending on the size of the blood vessel that they affect.

The macrovascular complications are:

• Coronary artery disease
• Cerebrovascular disease
• Peripheral vascular disease.

The microvascular complications are:

• Nephropathy – kidney disease
• Retinopathy – affecting the eyes, sometimes called maculopathy
• Neuropathy – affecting both the peripheral and central nervous system

Diabetic nephropathy

Diabetic nephropathy is the leading cause of chronic kidney disease (CKD) in people with diabetes and is associated with those who have had diabetes for over ten years and those with the poorest glycaemic control. The clinical hallmark of diabetic nephropathy is the presence of proteinuria on urinalysis, which can be quantified by a urine albumin creatinine ratio (ACR) and protein creatinine ratio (PCR), leading to progressive chronic kidney disease. Both Type 1 and Type 2 diabetes have equivalent rates of proteinuria and end stage renal disease.

On renal biopsy, the pathological feature most associated with diabetic nephropathy is the presence of glomerulosclerosis. Early histopathological changes involve glomerular basement membrane thickening, mesangial expansion, and podocyte depletion, progressing to glomerulosclerosis. Few patients require renal biopsy to establish the diagnosis, however.

The renal involvement of diabetes in many diabetic patients is clinically silent and often only picked up as part of screening.

Prevention and management of diabetic complications include both non-pharmacological and pharmacological options. Lifestyle changes should be addressed in every diabetic patient, including smoking cessation, increasing exercise, as well as managing other cardiovascular risk factors such as hypertension and hyperlipidaemia. In diabetic nephropathy, good blood pressure control is important in reducing proteinuria and slowing the rate of decline of renal function. Treatment with an ACE inhibitor or angiotensin receptor blocker (ARB) should be initiated in all patients with an ACR ≥ 3mg/mmol, even if the blood pressure is normal. Tight glycaemic control through lifestyle factors and insulin/oral hypoglycaemic medications is paramount in reducing all diabetic complications.