Effect of metformin on serum lipoprotein lipase mass levels and LDL particle size in type 2 diabetes mellitus patients.

We previously reported that lipoprotein lipase mass levels in preheparin serum (preheparin LPL mass) was significantly lower in type 2 diabetes mellitus compared to healthy subjects and that low preheparin LPL mass may be a high-risk factor of coronary atherosclerosis. The aim of this study was to clarify the effects of metformin on serum lipoprotein lipase mass levels (preheparin LPL mass), adiponectin and lipid metabolism in patients with type 2 diabetes mellitus. Twenty-eight patients with type 2 diabetes mellitus (HbAlc>7.0%), who were already receiving sulfonylurea agents, took metformin 500 mg orally twice daily for 3 months. Fasting blood glucose (FBG), immunoreactive insulin (basal IRI) and HbAlc decreased significantly after metformin treatment. LDL-Rm ratio decreased significantly (from 0.3521+/-0.046 to 0.3339+/-0.030, P<0.05) and preheparin LPL mass increased significantly (from 42.5+/-3.2 to 50.6+/-3.5 ng/ml, P<0.0005), but adiponectin was unchanged. The correlation of a change of LDL-Rm ratio and a change of preheparin LPL mass showed a negative correlation tendency. The changes in LDL-Rm ratio and preheparin LPL mass were independent of the hypoglycemic effect of metformin. These results suggest that metformin may increase LPL production, thereby increasing LDL particle size. These effects might be independent of the hypoglycemic effect of metformin.

Preheparin serum lipoprotein lipase mass might be a biomarker of metabolic syndrome.

Lipoprotein lipase mass in preheparin serum (preheparin LPL mass) is assumed to reflect some of the LPL production in the whole body and insulin sensitivity. While metabolic syndrome is a common underlying condition for cardiovascular diseases, biological marker of this syndrome has not been fully established. To clarify the characteristics of preheparin LPL mass in metabolic syndrome, 362 Japanese subjects were studied to examine the relationship between symptoms of metabolic syndrome and preheparin LPL mass and compare with plasma adiponectin. Furthermore the relation with urinary 8-hydroxydeoxyguanosine (8-OHdG) that reflects oxidative stress to DNA was also studied. Both preheparin LPL mass and plasma adiponectin correlated positively with HDL-cholesterol and negatively with body weight and triglyceride. Only preheparin LPL mass showed a negative correlation with fasting blood glucose and HbA1c. Both mean preheparin LPL mass and plasma adiponectin decreased with an increase in severity of the metabolic syndrome with/without obesity and with/without diabetes. The correlation coefficient between preheparin LPL mass and plasma adiponectin was r=0.562. A negative correlation between preheparin LPL mass and urinary 8-OHdG was observed. These results suggest that low preheparin LPL mass may reflect systemic oxidative stress and also a biomarker of the severity of metabolic syndrome.

Probucol and atorvastatin decrease urinary 8-hydroxy-2'-deoxyguanosine in patients with diabetes and hypercholesterolemia.

To clarify whether probucol and statins suppress oxidative stress in diabetic patients, we studied the effects of probucol and the statin atorvastatin on urinary 8-hydroxy-2'deoxyguanosine (8-OHdG) levels in diabetics with hypercholesterolemia. A randomized, open study was performed on a total of 36 patients with type 2 diabetes and hypercholesterolemia. The patients were randomly assigned to a probucol group (500 mg/day, n = 18) or an atorvastatin group (10 mg/day, n = 18). During three months, total- and LDL-cholesterol decreased significantly in both groups. LDL-cholesterol was significantly lower in the atorvastatin group than probucol group. HDL-C decreased significantly in the probucol group and did not change in the atorvastatin group. 8-OHdG decreased significantly in both groups after 3 months; 12.4 +/- 7.5 to 8.1 +/- 4.2 ng/mg/Cr in the atorvastatin group (p < 0.05) and 12.3 +/- 8.8 to 6.8 +/- 2.6 ng/mg/Cr in the probucol group (p < 0.05), and these changes did not differ significantly between the two groups. But, in patients with high 8-OHdG levels (more than 10 ng/mg/Cr) before administration, urinary 8-OHdG decreased significantly from 19.5 +/- 4.9 to 9.2 +/- 3.4 ng/mg Cr (p < 0.01) in the atorvastatin group, and from 19.7 +/- 8.2 to 6.67 +/- 2.2 ng/mg Cr (p < 0.01) in the probucol group. Urinary 8-OHdG was significantly lower in the probucol group than in the atorvastatin group after the second and third months of administration (p < 0.05). These results suggest that while probucol and atorvastatin both reduce systemic oxidative stress, probucol might be the more useful in patients with strong oxidative stress.

Enhancement of serum lipoprotein lipase mass levels by intensive insulin therapy.

We previously reported that lipoprotein lipase mass level in preheparin serum (preheparin LPL mass) was significantly lower in type 2 diabetes mellitus compared to healthy subjects and increased by conventional insulin therapy using NPH (intermediate-acting) insulin. The aim of this study was to investigate the effects of intensive insulin therapy on preheparin LPL mass. Thirty-two subjects (total group) with type 2 diabetes receiving treatment by NPH insulin injection twice a day in the morning and evening were switched to basal bolus insulin (BBI) therapy (fast-acting insulin after each meal and NPH insulin before bedtime). In 14 subjects, the total daily insulin dose was not change after switching to BBI therapy (iso-dose group). After 3 months of BBI therapy, preheparin LPL mass increased significantly from 47 to 56 ng/ml in total group. Glycosylated hemoglobin and serum triglyceride levels decreased significantly, and high-density lipoprotein-cholesterol increased significantly. Low-density lipoprotein levels did not changed but increase in size was suggested by PAG disc electrophoresis. Similar changes were observed in the iso-dose group. These results suggest that BBI therapy enhances preheparin LPL mass, accompanied by antiatherogenic changes in glucose and lipid metabolism.