Type 2 diabetes and obesity impair kidney function. Researchers have examined their respective contributions to urinary albumin excretion ( UAE ) and glomerular filtration rate ( GFR ) in patients with type 2 diabetes and morbid obesity.
Cross-sectional, monocentric study of kidney function in patients with type 2 diabetes classified into four body mass index ( BMI ) stages: non-obese ( less than 25kg/m2, n=157 ); overweight ( 25 to less than 30, n=311 ); obesity ( 30 to less than 40, n=310 ); and morbid obesity ( greater than or equal to 40, n=77 ), with 84 similarly staged controls without diabetes.
UAE classes were defined as normal ( less than 30mcg/mg creatinine ), microalbuminuria ( 30-299 ), or macroalbuminuria ( greater than or equal to 300 ) from 3 consecutive urine samples.
GFR was measured by 51Cr EDTA plasma disappearance ( adjusted and unadjusted to 1.73m2 body surface area, as obesity increases body surface ).
Participants with type 2 diabetes had same age, diabetes duration, and HbA1c across BMI stages.
UAE was higher in participants with type 2 diabetes ( p less than 0.0001 ), and increased with obesity stages ( p less than 0.0001 ).
After adjustment for age, sex, systolic blood pressure and type 2 diabetes status, morbid obesity was associated with a risk of microalbuminuria (odds ratio, OR=1.99, 95% CI 1.35-2.98, p=0.0007 ) and macroalbuminuria ( OR=2.33, 95% CI 1.25-4.22, p=0.006 ).
The body surface adjusted GFR was lower in patients with type 2 diabetes than in controls ( p less than 0.0001 ), and declined with obesity stages, contrary to controls.
An interaction of diabetes and obesity was seen with unadjusted GFR values ( p=0.002 ).
In conclusion, morbid obesity interacts with type 2 diabetes to aggravate UAE and GFR. Treatment strategies should focus on both conditions to protect kidney function in these patients. ( Xagena )
Belhatem N et al, Diabetes Res Clin Pract 2015; Epub ahead of print