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Soon after the onset of type 1 diabetes, renal hypertrophy and hyperfiltration become manifest, particularly among patients who will subsequently develop diabetic nephropathy. Whether these early renal dysfunctions are involved in the pathogenesis of diabetic nephropathy is currently unclear. We evaluated, during the same day, kidney volume and glomerular filtration rate (GFR) in 146 patients with type 1 diabetes and normal renal function. All the individuals were then monitored for a mean of 9.5 +/- 4.4 years for the development of microalbuminuria. Kidney volume and GFR were reevaluated in a subset of 68 patients 4 years after baseline. During follow-up, microalbuminuria developed in 27 of 146 diabetic patients. At baseline, kidney volume (312.8 +/- 52.6 vs. 281.4 +/- 46.1 vs. 236.8 +/- 41.6 ml/1.73 m(2), P < 0.05) but not GFR was increased in patients predisposed to microalbuminuria. Risk of progression was higher in patients with increased kidney volume (P = 0.0058). Patients predisposed to microalbuminuria showed a stable increase in kidney volume (P = 0.003), along with a faster decline of GFR (P = 0.01). Persistent renal hypertrophy and faster decline of GFR precede the development of microalbuminuria in type 1 diabetes. These findings support the hypothesis that renal hypertrophy precedes hyperfiltration during the development of diabetic nephropathy.

Objective: Height and weight changes during the first 3 years of diabetes were prospectively followed in 152 diabetic children and adolescents., Research Design and Methods: The study sample consisted of 152 Caucasian diabetic patients (84 boys; 68 girls) followed from diabetes onset in the Paediatric Diabetes Unit and 80 Caucasian normal subjects (49 boys; 31 girls) assessed in the Outpatient General Paediatric Clinic of the same hospital for routine examination and not affected by problems that might influence growth. Diabetic patients and control subjects were consecutively enrolled in the study between 1989 and 1992; diabetic patients with positive markers for celiac disease (positive antiendomysial antibodies) and thyroid disease (positive antimicrosomial antibodies) or any other chronic disease were not considered in the study. Mean age of diabetic patients (8.9 +/- 4.1 years) and control subjects (8.5 +/- 4.2 years) at recruitment in the study was similar., Results: At onset of diabetes, the mean height expressed as the height standard deviation score (HSDS) was significantly greater than the expected values (P < 0.0001) and was independent of sex and pubertal stage. During the first 3 years of diabetes, HSDS decreased significantly (F = 6.9; P < 0.001). Meanwhile, growth velocity as standard deviation score (SDS) decreased significantly between the 1st and 2nd year (-0.12 +/- 2.1; -0.76 +/- 2.6, respectively; P < 0.05), but it was similar between the 2nd and 3rd year of diabetes. Weight expressed as SDS increased significantly during the first 2 years of diabetes but not thereafter. Height changes during the study period were independent from pubertal stage and sex. Metabolic control and insulin requirement, in our series, were not clearly related to height and weight changes., Conclusions: Diabetic patients at onset of diabetes are taller than age- and sex-matched nondiabetic subjects. During the first years of the disease, linear growth decreases independently of metabolic control and weight changes.

Objective: This study has been designed to follow prospectively the GFR and UAE of young patients with short-term IDDM and normal UAE., Research Design and Methods: The study population consisted of 19 patients with glomerular hyperfiltration and 19 patients with normal GFR, matched for duration of diabetes and age. GFR has been assessed by radioisotopic tracer and UAE by RIA at the beginning of the study and after 30.5 +/- 10.4 mo of follow-up., Results: GFR decreased in the two groups btt delta GFR of patients with glomerular hyperfiltration was greater than delta GFR of patients with normal GFR (0.83 +/- 0.55 vs. 0.28 +/- 0.63 ml.min-1.mo-1; P < 0.01). UAE, BP, and prevalence of microalbuminuria were comparable between the two groups at follow-up. Rate of fall of GFR was positively correlated with initial GFR (r = 0.59, P < 0.001) but not with initial UAE, BP, or changes in HbA1C, UAE, BP, or pubertal development during follow-up., Conclusions: Investigation of kidney function in children and adolescents with IDDM over a 3-yr follow-up period shows that glomerular hyperfiltration is characterized by a greater decline in GFR without an increased rate of appearance of microalbuminuria, than in patients with normal GFR.