SKELETAL-MUSCLE LIPOPROTEIN-LIPASE ACTIVITY IN INSULIN-DEPENDENT DIABETIC-PATIENTS WITH AND WITHOUT ALBUMINURIA

In patients with insulin-dependent diabetes mellitus (IDDM), albuminur ia reflects widespread vascular dysfunction. Albuminuria has been asso ciated to defects of heparan sulfate proteoglycan (HSPG) within the ex tracellular matrix. Our hypothesis is that loss of HSPG in vascular wa lls reduces the HSPG-bound lipoprotein-lipase activity (LPLA), thereby causing elevated levels of plasma triglyceride (TG) seen in IDDM pati ents with albuminuria. The aim of the present study was to evaluate wh ether LPLA in muscle capillaries could be related to TG in IDDM patien ts with and without albuminuria. This is a cross-sectional study inclu ding ten healthy control subjects (group C), nine patients with IDDM a nd urinary albumin excretion rate (AER) of 30 mg/24 h or less (group D -0) and 20 patients with IDDM and AER greater than 30 mg/24 h (group D -A). Muscle LPLA, plasma TG, total cholesterol, high-density lipoprote in cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and v ery-low-density lipoprotein cholesterol (VLDL) were measured. Between groups no difference in total cholesterol, TG, VLDL, and LDL was found . In patients with albuminuria, LPLA was reduced compared to controls, however, the difference between the groups was not statistically sign ificant [median (range)] 35.9 mU/g (20.4-103) versus 44.6 mU/g (28.2-5 7.2) and 40.9 mU/g (21.7-53.5) in group D-A, C, and D-0, respectively, p = 0.76, AER was not correlated to LPLA. An overall negative correla tion between TG and LPLA was found; r = -0.33, r = 0.04, supported by an overall significant positive correlation between LPLA and HDL; r = 0.35 p = 0.045. We conclude that, In insulin-dependent diabetes mellit us, skeletal muscle lipopotein-lipase activity is associated with plas ma triglyceride, while an association between lipoprotein-lipase activ ity and urinary albumin excretion is questionable.