Fasting blood glucose--a missing variable for GFR-estimation in type 1 diabetes?
OBJECTIVE
Estimation of glomerular filtration rate (eGFR) is one of the current clinical methods for identifying risk for diabetic nephropathy in subjects with type 1 diabetes (T1D). Hyperglycemia is known to influence GFR in T1D and variability in blood glucose at the time of eGFR measurement could introduce bias in eGFR. We hypothesized that simultaneously measured blood glucose would influence eGFR in adults with T1D.


METHODS
Longitudinal multivariable mixed-models were employed to investigate the relationships between blood glucose and eGFR by CKD-EPI eGFRCYSTATIN C over 6-years in the Coronary Artery Calcification in Type 1 diabetes (CACTI) study. All subjects with T1D and complete data including blood glucose and cystatin C for at least one of the three visits (n = 616, 554, and 521, respectively) were included in the longitudinal analyses.


RESULTS
In mixed-models adjusting for sex, HbA1c, ACEi/ARB, protein and sodium intake positive associations were observed between simultaneous blood glucose and eGFRCYSTATIN C (β±SE:0.14±0.04 per 10 mg/dL of blood glucose, p<0.0001), and hyperfiltration as a dichotomous outcome (OR: 1.04, 95% CI: 1.01-1.07 per 10 mg/dL of blood glucose, p = 0.02).


CONCLUSIONS
In our longitudinal data in subjects with T1D, simultaneous blood glucose has an independent positive effect on eGFRCYSTATIN C. The associations between blood glucose and eGFRCYSTATIN C may bias the accurate detection of early diabetic nephropathy, especially in people with longitudinal variability in blood glucose.
Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, United States of America.
Petter
P
Bjornstad
University of Colorado School of Pharmacy, Aurora, Colorado, United States of America.
R Brett
RB
McQueen
Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, United States of America; Barbara Davis Center for Diabetes, University of Colorado School of Medicine, Aurora, Colorado, United States of America.
Janet K
JK
Snell-Bergeon
Department of Medicine, Division of Nephrology, Toronto General Hospital, University of Toronto, Ontario, Canada.
David
D
Cherney
Department of Biostatistics, University of Colorado Denver, Aurora, Colorado, United States of America.
Laura
L
Pyle
Department of Medicine, Division of Endocrinology, Mount Sinai Hospital, University of Toronto, Ontario, Canada.
Bruce
B
Perkins
Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, United States of America; Barbara Davis Center for Diabetes, University of Colorado School of Medicine, Aurora, Colorado, United States of America.
Marian
M
Rewers
Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, United States of America; Barbara Davis Center for Diabetes, University of Colorado School of Medicine, Aurora, Colorado, United States of America.
David M
DM
Maahs
D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D015331:Cohort Studies; D055316:Cystatin C / Q000032:analysis; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications; D003928:Diabetic Nephropathies / Q000097:blood* / Q000209:etiology; D005215:Fasting / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D061205:Vascular Calcification / Q000097:blood / Q000150:complications; D055815:Young Adult
D001786:Blood Glucose; D055316:Cystatin C