Poor Glycemic Control Linked to Development of Microalbuminuria

Poor glycemic control is linked to the development of microalbuminuria in childhood-onset type 1 diabetes.

The risk for progression to macroalbuminuria was similar to that in adult-onset disease, but because it occurs in young adult life, the study authors suggest that early intervention in adolescents with normal blood pressure might help improve prognosis.

Rakesh Amin, from the University of Cambridge, United Kingdom, and colleagues write,  "In adults with type 1 diabetes microalbuminuria is an early marker of structural renal disease and a risk factor for the development of macroalbuminuria."  "The prognostic value of microalbuminuria for progression to macroalbuminuria has not been adequately determined in a childhood cohort."

The goal of this study was to describe independent predictors for the development of microalbuminuria and progression to macroalbuminuria in patients with childhood-onset type 1 diabetes.

Investigators in the Oxford regional prospective study enrolled 527 participants with a diagnosis of type 1 diabetes at a mean age of 8.8 ± 4.0 years. Mean duration of follow-up was 9.8 ± 3.8 years, and the primary endpoint was annual measurement of glycated hemoglobin (HbA1c) levels and evaluation of urinary albumin-to-creatinine ratio.
After 10 years of diabetes, the cumulative prevalence of microalbuminuria was 25.7% (95% confidence interval [CI], 21.3% to 30.1%). This increased to 50.7% (95% CI, 40.5% to 60.9%) after 19 years of diabetes and a total of 5182 patient-years of follow-up.

The only modifiable adjusted predictor for microalbuminuria was elevated HbA1c levels. Hazard ratio (HR) per 1% increase in HbA1c was 1.39 (95% CI, 1.27 – 1.52). Blood pressure and smoking history did not predict the development of microalbuminuria.

Nearly half (48%) of patients had persistent microalbuminuria, and 13.9% ultimately progressed to having macroalbuminuria (95% CI, 12.9% to 14.9%). Mean age of the patients at progression to macroalbuminuria was 18.5 ± 5.8 years.
Modifiable predictors of macroalbuminuria were higher HbA1c levels, persistent microalbuminuria, and intermittent microalbuminuria.

"In childhood onset type 1 diabetes, the only modifiable predictors were poor glycemic control for the development of microalbuminuria and poor control and microalbuminuria (both persistent and intermittent) for progression to macroalbuminuria," the study authors write. "Risk for macroalbuminuria is similar to that observed in cohorts with adult onset disease but as it occurs in young adult life early intervention in normotensive adolescents might be needed to improve prognosis."

Practice Pearls

• After 19 years of diabetes, microalbuminuria had developed in more than half of patients with childhood-onset type 1 diabetes, and nearly half had persistent microalbuminuria. Microalbuminuria occurred more frequently and was more common in girls. The only modifiable adjusted predictor for microalbuminuria was elevated HbA1c level. Blood pressure and smoking history did not predict the development of microalbuminuria.
• Mean age of progression to macroalbuminuria was 18.5 ± 5.8 years. Modifiable predictors of macroalbuminuria were higher HbA1c levels, persistent microalbuminuria, and intermittent microalbuminuria. Unlike previous findings in adults, children taking ACE inhibitors in this study had higher rates of progression to macroalbuminuria.

BMJ. Published online March 18, 2008. 366:697-701.

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