Diabetic nephropathy

Current Care Summary
Working group set up by the Finnish Medical Society Duodecim and the Finnish Society of Nephrology
14.8.2008

Current Care Guideline «Diabeettinen nefropatia»1 and Summary «Diabeettinen nefropatia»2 in Finnish

Prevalence

The earliest sign of diabetic nephropathy is chronic microalbuminuria. Microalbuminuria is detected in approximately 20–30 per cent of type 1 diabetes patients after 15 years of suffering from the illness while, for type 2 patients, it is frequently present upon the diagnosis of diabetes (A). A glucose imbalance (A), hypertension (A), smoking (B) and genetic factors predispose the patient to the development of nephropathy.

Diagnostics and screening

As a method of diagnosing microalbuminuria, either the determination of the albumin/creatinine ratio from a spot sample (U-alb/crea) or a timed overnight collection of urine for albumin (cU-alb) (B) are used.

For type 1 diabetes patients, microalbuminuria should be screened annually after five years of illness (D) and, for type 2 patients, immediately after the diagnosis of diabetes (D). For diabetics, microalbuminuria prognosticates higher risks of mortality, including death from cardiovascular diseases (A). Alongside microalbuminuria or proteinuria examinations, the estimated glomerular filtration rate (eGFR) is determined annually. The most highly recommended method of measuring kidney function is to determine the eGFR on the basis of the plasma creatinine concentration, using either the Cockroft–Gault (CG) or MDRD formula (B). In comparison to a single serum creatinine determination, the determination of plasma cystatin C may be more effective in revealing mild renal failure.

Prevention and treatment of nephropathy

An intensive long-term treatment, holistically targeting several risk factors, would prevent the progression of nephropathy (A). Such treatment aims to optimise blood pressure, glucose levels and lipid values at their respective recommended levels, while not neglecting the significance of lifestyle guidance in the prevention and treatment of the disease.

Treatment of hypertension

The treatment of hypertension in diabetic nephropatia is based on a target value of less than 130/80 mmHg. If proteinuria exceeds 1 g/day, the target value is less than 125/75 mmHg. Primary medication for the prevention and treatment of diabetic nephropathy includes ACE inhibitors and angiotensin receptor blockers since, in addition to lowering blood pressure, they also effectively reduce proteinuria (A).

Treatment of hyperglycaemia

A stable glucose balance prevents the appearance of nephropathy (A) and an improvement in the glucose balance prevents its progression. The target HbA1c is less than 6–7 per cent.

Other treatments

While non-smoking is likely to prevent the worsening of diabetic nephropathy (C), its key effect lies in reducing the risk of arteriosclerosis. A protein-restricted diet may slow down the progression of diabetic nephropathy into renal failure, at least for patients with type 1 diabetes (B). The treatment of hyperlipidemia seems to decelerate the progression of diabetic nephropathy (B).

Follow-up of treatment and consultations

Care chains are formed in line with regional resources. Consultation with an internist, diabetologist or nephrologist is indicated if, in spite of enhanced treatment, nephropathy progresses (albuminuria increases or GFR reduces) or a differential diagnostic or major treatment problem occurs.

Kaj Metsärinne

Agneta Ekstrand

Per-Henrik Groop

Merja Hanski

Jorma Komulainen

Leo Niskanen

Marja Puurunen

Heikki Saha