Modulation by blood glucose levels of activity and concentration of paraoxonase in young patients with type 1 diabetes mellitus

Paraoxonase (PON) is a high-density lipoprotein (HDL)-associated esterase, which may prevent the transformation of low-density lipoproteins (LDL) into biologically active, atherogenic particles. PON concentration end activity are affected by PON1 gene polymorphisms and found to be altered in type 2 diabetes patients with retinopathy, We investigated serum PON concentration , in vitro activity and polymorphism at position 54 (L/M. Leu-Met54) in 193 Caucasian adolescents and young adults (88 males, 105 females) with type 1 diabetes mellitus, as well as its relationship to the presence of retinopa thy. An inverse linear correlation was found between blood glucose levels a nd both serum PON concentration (r = -.20, P = .017) and its activity (r = -0.17, P = .037). Patients with elevated blood glucose values (greater than or equal to 10 mmol/L) had significantly lower levels of both PON concentr ation (P = .003) and activity (P =.028) than those with lower glucose level s. After adjusting for blood glucose and diabetes duration, PON activity wa s significantly higher in patients with different stages of retinopathy com pared with those without retinopathy (P = .003). The L/L genotype was close ly associated with the presence of retinopathy (P < .0001). These data show that young people with type 1 diabetes and the L/L polymorphism at positio n 54 of PON1 gene are more susceptible to retinal complications. However, t he role of serum PON concentration and activity as a possible marker for mo nitoring late microvascular complications in these patients has to be estab lished. Copyright (C) 2001 by W.B. Saunders Company.