Importance of glycemic control on the course of glomerular filtration rate in type 2 diabetes with hypertension and microalbuminuria under tight blood pressure control.
OBJECTIVE
To evaluate the role of glycemic control on the evolution of glomerular filtration rate (GFR) in type 2 diabetes (T2DM) with mild-moderate hypertension under tight blood pressure control, and to address the current controversy whether diabetic nephropathy worsens, independently of blood pressure, proportionally to HbA1c at any physiological level or only when HbA1c is above a 7.5-8% threshold.


RESULTS
T2DM (N=127) during early stage diabetic nephropathy characterized by microalbuminuria were followed during a 2 year multicenter study. Individual GFR profiles were accurately obtained by (51)Cr - EDTA bolus injections and analyzed with linear statistical mixed-effects models. GFR at baseline was significantly negatively correlated with age and plasma creatinine concentration (P<or=0.0001), and GFR declined, on average, by 4.0 ml/min 1.73 m(2)/year (P=0.001). A significant correlation was found between individual GFR decline rate and average systolic (SBP) and diastolic (DBP) blood pressures (-0.254 (0.736) ml/min 1.73 m(2)/year per mmHg increase in SBP (DBP), P=0.041 (0.014)) and % of glycated hemoglobin (HbA1c) (-1.78 ml/min 1.73 m(2)/year per % increase in HbA1c, P=0.048). This implies a 44% increase/reduction in GFR decline rate for 1% HbA1c increase/reduction around 7.0% (i.e. 5.79 and 2.24 ml/min 1.73 m(2)/year at 8% and 6% HbA1c, respectively).


CONCLUSIONS
This study demonstrates that, despite tight blood pressure control, an accurate glycemic control till very low patterns of HbA1c (from 10-11% to 5-6%) is needed to delay the progression of GFR decay in Mediterranean T2DM in south Europe with microalbuminuria.
Thomaseth
Karl
K
National Research Council, Institute of Biomedical Engineering, CNR, Corso Stati Uniti 4, 35127 Padova, Italy. karl.thomaseth@isib.cnr.it
Pacini
Giovanni
G
Morelli
Patrizia
P
Tonolo
Giancarlo
G
Nosadini
Romano
R
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000503:physiopathology*; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D005919:Glomerular Filtration Rate; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human