Vascular complications

Diabetic kidney disease

Nephropathy

• Diabetic nephropathy and end-stage renal failure have been a major cause of mortality amongst young adults with type 1 diabetes
• In recent decades a decrease in clinical nephropathy in some countries probably reflects improvements in diabetes management and glycemic control
• Increasing and persistently elevated urinary albumin excretion may predict later diabetic nephropathy
• Elevated blood pressure is an associated feature of diabetic kidney disease

Microalbuminuria

• The 95th centile for albumin excretion in non-diabetic children is 7.2–7.6 µg/min
• Persistent microalbuminuria is defined in a minimum of two out of three consecutive urine specimens
  Albumin excretion rate (AER) 20–200 µg/min in timed overnight urine collections
  or
  AER 30–300 mg/24 h in 24-h urine collections
  
• Alternative definitions
  Albumin/creatinine ratio (ACR) 2.5–25 mg/mmol (spot urine) (Europe)
  
  [3.5–25 mg/mmol has been proposed in females because of lower creatinine excretion]
  ACR 30–300 mg/g (spot urine) (North America)
  Albumin concentration 30–300 mg/l (early morning urine)
  

Microalbuminuria screening

• Screening may be performed by early morning urine albumin concentration or spot urine ACR or by timed urine collection
• Abnormal screening values should be confirmed by repeated sampling to demonstrate persistent microalbuminuria

Recommendation

Age of microalbumin screening Prepubertal onset of diabetes: 5 years after onset or at age 11 years, or at puberty (whichever is earlier), and annually thereafter Pubertal onset of diabetes: 2 years after onset, and annually thereafter

Microalbuminuria monitoring

• Abnormal screening tests should be repeated, as pediatric studies have shown that apparently ‘persistent’ microalbuminuria may disappear
• Urinary albumin tests should be accompanied by measurements of blood pressure at least annually
• Blood pressure values should be compared with age-appropriate centile charts. Confirmation of hypertension may be assisted by 24-h ambulatory blood pressure measurements
• When persistent microalbuminuria is confirmed, screening for retinopathy, neuropathy and lipid abnormalities is also recommended

Prevention and intervention

• Improve BG control
• Strongly discourage smoking
• Encourage healthy exercise
• Discourage excessive nutritional protein intake (recommended maximum of 1.0–1.2 g/kg body weight per day)
• Intervention for hypertension: no clear consensus but blood pressure should probably be maintained at less than the 95th centile for age and maturity

• Persistent and progressive albuminuria has been found to be improved by the use of ACE inhibitors. Progression to overt nephropathy may be delayed but their place in protecting long-term renal function in young people has not yet been established. There is early evidence that even without hypertension, ACE inhibitors should be considered when persistent microalbuminuria has been confirmed
• The introduction of ACE inhibitors must be combined with monitoring of renal function. ACE inhibitors are not licenced for use in pregnancy