Diabetic nephropathy is the commonest cause of end stage renal disease in the western world. Diagnosis is made on a clinical and biochemical grounds, typically the presence of diabetes for 10-20 years or more, a progressive deterioration in renal function associated with worsening proteinuria, no haematuria, and usually other microvascular complications such as retinopathy or neuropathy. The mainstay of management is anti-hypertensive therapy with ACE-inhibitors and/or angiotensin receptor blockers. Eventually dialysis or transplantation are necessary in a proportion of cases.

Does the patient have any symptoms or do they feel completely well?

Diabetic nephropathy is commonly a completely asymptomatic condition until the patient has quite advanced renal impairment and it is therefore essential that annual screening by measuring Us and Es and performing urinalysis for microalbuminuria are undertaken.

How long has the patient had diabetes?

In general, the longer the patient has had diabetes the greater the risk of complications although this is is a very approximate guide and it is certainly possible to have had diabetes for only a few years and already developed complications (especially so for T2DM).

Conversely, some patients can have diabetes for many decades and develop few or any complications.

Does the patient have other microvascular complications?

The presence of other microvascular complications such as retinopathy and neuropathy increases the odds that the patient will also develop nephropathy, but this is only a rule of thumb and it certainly shouldn't be inferred that patients without other microvascular complications cannot, or will not develop nephropathy.

How good has the glycaemic control been over the years?

If there is a long history of poor glycaemic control with chronically high HbA1c then development of microvascular complications such as nephropathy is more likely than if control has generally been very good.

Has the patient been feeling non specifically unwell, experiencing pruritus, anorexia and weight loss? 

These may be symptoms of uraemia, but the renal impairment should normally be picked up long before the patient develops these symptoms by the deterioration on the annual eGFR.

Take a drug history

It is essential to ensure that a patient with deteriorating renal function is not on potentially nephrotoxic drugs such as non steroidal anti inflammatories.

If there has been a sudden step-wise deterioration in renal function it is also important to check that this didn't co-incide with the onset of ACE inhibitor therapy. Once the serum creatinine is above 150 umol/L or the eGFR is below 30 ml/min, metformin therapy should be withdrawn.

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