Evolution of Renal Hyperfiltration and Arterial Stiffness From Adolescence Into Early Adulthood in Type 1 Diabetes

OBJECTIVE: To determine, in a small but carefully physiologically characterized cohort of subjects with uncomplicated type 1 diabetes, the changes in renal hemodynamic function and arterial stiffness that occur over time as the participants transitioned from adolescence into early adulthood. The classical paradigm for type 1 diabetes suggests that glomerular filtration rate (GFR) declines in patients with renal hyperfiltration, but the natural history of peripheral vascular function abnormalities in uncomplicated type 1 diabetes is less well understood, particularly as patients transition from adolescence to early adulthood. RESEARCH DESIGN AND METHODS: Renal hemodynamic function (inulin and p-aminohippuric acid clearance), blood pressure, arterial stiffness (radial augmentation index), albumin excretion, and circulating renin-angiotensin system measures were obtained during clamped euglycemia at baseline and at follow-up 6.8 ± 2.5 years later in 10 patients with hyperfiltration (GFR ≥135 mL/min/1.73 m(2)) and in 8 with normofiltration. RESULTS: Compared with baseline values, GFR (171 ± 20 to 120 ± 15 mL/min/1.73 m(2)) and filtration fraction (FF, 0.24 ± 0.06 to 0.18 ± 0.03) declined in hyperfilterers (ANOVA P ≤ 0.033), and renal vascular resistance increased (0.0678 ± 0.0135 to 0.0783 ± 0.0121 mmHg/L/min, P = 0.017). GFR and FF did not change in normofiltering subjects. In contrast, the radial augmentation index decreased in hyperfiltering (1.2 ± 11.7 to −11.0 ± 7.8%) and normofiltering (14.3 ± 14.0 to 2.5 ± 14.6%) subjects (within-group changes, ANOVA P ≤ 0.030). The decline in circulating aldosterone levels was similar in both groups. CONCLUSIONS: During the transition from adolescence to early adulthood, hyperfiltration is not sustained in subjects with type 1 diabetes, whereas GFR remains stable in normofiltering subjects. Our findings suggest early normofiltration may predict stable renal function. In contrast, arterial stiffness decreased in all patients regardless of filtration status, suggesting that age-related increases in arterial stiffness occur at older ages.