Diabetic kidney disease 

Diabetic kidney disease develops slowly over many years – almost one in five people with diabetes will require treatment for it at some point. Symptoms develop gradually and can include oedema of the ankles, feet and hands, haematuria, fatigue, shortness of breath and nausea, all of which are due to deteriorating renal function resulting in waste products and fluid being cleared less efficiently. Damage to the filtering elements of the kidney causes protein to leak into the urine – an important marker for diabetic kidney disease.

Keeping blood glucose and blood pressure under control, stopping smoking, staying active and eating healthily all reduce a patient’s risk of developing kidney disease. Tight glucose control reduces the incidence of micro- or macro-albuminuria and can slow glomerular filtration rate decline and possibly progression to end-stage kidney disease (ESKD). This is why the following tests are essential in regularly monitoring changes in kidney function over time:

• Albumin: creatinine ratio (ACR) urine test
• Estimated glomerular filtration rate (eGFR) blood test. 

The earliest sign of diabetic kidney disease is leakage of albumin in the urine. Even a small amount of protein in the urine is significant and, if found, increases the need for good control of both blood pressure and diabetes. A GFR test can diagnose kidney disease at an early stage when it is most treatable and is also used to monitor people with diabetes and hypertension. 

The UK National Diabetes Audit shows that the urine albumin check is completed much less frequently than other checks (around 60 per cent of patients with type 2 diabetes in 2018-19 and 48 per cent with type 1).

Blood pressure should be below 140/80mmHg for people with diabetes, and for those who have kidney or eye disease or other complications, the target BP is 130/80mmHg. The aim of this tighter blood pressure control is to slow the rate of decline of GFR and reduce proteinuria. 

The BNF advises that “provided there are no contraindications, all diabetic patients with nephropathy causing proteinuria or with established microalbuminuria should be treated with an ACE inhibitor or an angiotensin-II receptor antagonist, even if the blood pressure is normal”.

The risk of complications from chronic kidney disease increases as the condition progresses, and includes acute kidney injury, hypertension and dyslipidaemia, cardiovascular disease, renal anaemia, mineral and bone disorders, peripheral neuropathy and myopathy, malnutrition, malignancy and ESKD. Diabetes is the most common cause of ESKD, with patients five times more likely to need dialysis or a transplant than those without diabetes.