Hyperfiltration in patients with type I diabetes mellitus: a prevalence study.
OBJECTIVE
An increase in glomerular filtration rate (GFR) and renal plasma flow (EFPR) may be considered as prognostic factors for the progression of diabetic nephropathy; however the real predicting value of hyperfiltration in the development of incipient and overt nephropathy is as yet unknown. We have examined the prevalence of hyperfiltration in a population of normotensive adult IDDM patients and the possible effect of long-term metabolic control on glomerular hemodynamics.


METHODS
We measured GFR and ERPF values in 177 normotensive, normoalbuminuric insulin-dependent diabetic patients and in 30 healthy subjects by single bolus intravenous injection of 1 miroCu/kg [51Cr]-EDTA and 0.2 microCu/kg [125I]-Hippuran intravenously. We have correlated the GFR values with parameters of metabolic control over the last 3 years and with age, sex, and duration of diabetes.


RESULTS
Patients with a GFR greater than the 95 degrees percentile value of controls (135 ml/min/1,73 m2) were defined as hyperfiltering. They represented the 55.9% (99/177) of our population. We found a strong correlation between GFR and ERPF (p <0.001), and between GFR and average HbA1c levels (p = 0.016) in multiple regression analysis, with age, sex, ERPF, and average HbA1c levels entered as variables (r2 = 0.45). There appeared to be no correlation with the duration of the disease.


CONCLUSIONS
Long-term hyperglycemia provides a significant contribution in GFR and a poor metabolic control is predictive of overt nephropathy. In this study hyperfiltration does not appear to be the major factor of diabetic nephropathy. A follow-up of these patients is necessary to clarify the role of hyperfiltration in the development of overt nephropathy in diabetes.
Cotroneo
P
P
Department Internal Medicine and Geriatric, Università Cattolica del Sacro Cuore, Roma, Italy.
Manto
A
A
Todaro
L
L
Manto
A
A
Pitocco
D
D
Saponara
C
C
Vellante
C
C
Maussier
M L
ML
D'Errico
G
G
Magnani
P
P
Ghirlanda
G
G
D000328:Adult; D000367:Age Factors; D002860:Chromium Radioisotopes; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology* / Q000517:prevention & control; D003928:Diabetic Nephropathies / Q000209:etiology / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006442:Glycated Hemoglobin / Q000032:analysis; D006439:Hemodynamics; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology / Q000517:prevention & control; D007457:Iodine Radioisotopes; D007678:Kidney Glomerulus / Q000503:physiopathology; D008297:Male; D015995:Prevalence; D011379:Prognosis; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D017595:Renal Plasma Flow / Q000502:physiology*; D012737:Sex Factors; D013997:Time Factors
D002860:Chromium Radioisotopes; D006442:Glycated Hemoglobin; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals