This paper is an edited version of Effective Health Care volume 6 number 1,¹ which summarises information originally derived from systematic reviews undertaken to inform national clinical practice guidelines,²³ supplemented and re-analysed by the NHS Centre for Reviews and Dissemination.

Renal complications of type 2 diabetes

Raised blood glucose levels and related microvascular disease are associated with progressive damage to the kidneys. This damage becomes detectable when protein (primarily albumin) is excreted in the urine in higher concentrations than normal. As the severity of the damage increases, the quantity of protein in the urine also increases. When the level of albumin in the urine is fairly low, the condition is known as microalbuminuria or incipient nephropathy; higher albumin excretion is described as proteinuria. Eventually the condition can lead to renal failure.²

Epidemiological studies report prevalence rates of microalbuminuria in patients with type 2 diabetes ranging from 8% to 32% with most estimates being around 25%.^4–15 Prevalence estimates for proteinuria range from 5% to 19% with most studies giving rates of around 15%.^569–111516 This variation may be a product of the criteria used to define the condition, the stage of the disease, and the methods used to assess it. Figures from the UK Prospective Diabetes Study (UKPDS), based on 3867 patients, suggest that about 12% have microalbuminuria (although using a high threshold) and 1.9% have proteinuria at the time of diagnosis of diabetes.¹⁷ A US study which followed 794 patients with type 2 diabetes who were initially free from proteinuria (defined as ≥30 μg protein/l urine) found that 1.3% developed renal failure within 10 years.¹⁸

A substantial proportion of patients treated in renal units in the UK have diabetes. Diabetic nephropathy is the most common single cause of renal failure among …