A simplified colorimetric method for measurement of the levels of glycosylation of proteins was developed by a modification of an existing method. Employing this method, the extent of nonenzymatic glycosylation of apolipoprotein B subspecies(B-100, B-74, B-26), LDL, VLDL and total serum proteins in human plasma obtained from patients with diabetes mellitus and control subjects was compared. Plasma LDL (1.019 < d < 1.063) and VLDL(d < 1.006) were separated using the sequential ultracentrifugation method, and the subspecies of apolipoprotein B were isolated by extracting them from polyacrylamide gels after they were separated by preparative SDS-polyacrylamide gel electrophoresis. Increases in the level of glycosylation of serum proteins, LDL, VLDL, and apo B subspecies obtained from diabetic patients were observed. Among them, the increases of glycosylated LDL and apo B-26 were most significant (p < .001). Also, good correlations were found between glycosylations of apo B-26 and LDL (r=.88), and glycosylation of LDL and LDL cholesterol level(r=.79). The results also showed an excellent correlation between levels of HbA1c and glycosylated apo B-26(r=.93).
Adult ; Colorimetry/methods* ; Diabetes Mellitus, Non-Insulin-Dependent/blood* ; Glycosylation ; Human ; Lipoproteins, LDL/blood*

BACKGROUND: Although insulin resistance and decreased insulin secretion are characteristics of established type 2 DM, which of these metabolic abnormalities is the primary determinant of type 2 DM is controversial. It is also not well known how insulin resistance and beta cell dysfunction influence serum insulin, proinsulin, proinsulin/insulin ratio in type 2 DM. METHODS: We compared serum insulin, proinsulin and proinsulin/insulin ratio in type 2 diabetic patients and control subjects. We also investigated the relationship between serum insulin, proinsulin and proinsulin/insulin ratio and several biochemical markers which represent insulin resistance or beta cell function. RESULTS: Insulin, proinsulin and proinsulin/insulin ratio were significantly higher in type 2 DM than control(p < 0.001). In diabetic patients, total insulin level was correlated with urinary albumin excretion rates(r = 0.224, p = 0.025) and body mass index(r = 0.269, p = 0.014). Proinsulin level was correlated with fasting C-peptide(r = 0.43, p = 0.002), postprandial 2 hour blood glucose(r = 0.213, p = 0.05) and triglyceride(r = 0.28, p = 0.022). Proinsulin/insulin ratio was positively correlated with fasting C-peptide(r = 0.236, p = 0.031), fasting blood glucose (r = 0.264, p = 0.015), postprandial 2 hour blood glucose(r = 0.277, p = 0.001) and triglyceride(r = 0.428, p < 0.001). In control subjects, insulin level was correlated with triglyceride(r = 0.366, p = 0.002). Proinsulin/insulin ratio was correlated with age(r = 0.241, p = 0.044). CONCLUSION: The serum levels of insulin and proinsulin seem to be associated with several markers of insulin resistance. Whereas proinsulin/insulin ratio might represent beta cell function rather than insulin resistance. But more studies are needed to clarify the mechanisms of elevated proinsulin/insulin ratio in type 2 DM.
Aged ; Diabetes Mellitus, Non-Insulin-Dependent/etiology ; Diabetes Mellitus, Non-Insulin-Dependent/blood* ; Female ; Human ; Insulin/blood* ; Insulin Resistance* ; Islets of Langerhans/physiopathology* ; Male ; Middle Age ; Proinsulin/blood* ; Sulfonylurea Compounds/pharmacology

In order to study the relationship between the serum ferritin level and the components of the insulin resistance syndrome in type 2 diabetic patients, we evaluated fifty type 2 diabetic patients who were selected according to NDDG/WHO criteria from those patients attending Korea University Hospital from 1997 to 1998. Twenty-five healthy non-diabetic subjects of comparable age and sex distribution acted as a control group. The results showed that the value of log ferritin was higher in the type 2 diabetes patients than the control subjects, but not at a statistically significant level (p = 0.09). Log ferritin was correlated with fasting blood sugar level (r = 0.235, p = 0.048) and body mass index (BMI) (r = 0.285, p = 0.05). In the type 2 diabetic patients, log ferritin was correlated with fasting C-peptide (r = 0.478, p = 0.009). In the control subjects, log ferritin was correlated only with BMI (r = 0.477, p = 0.012). In a stepwise multiple regression analysis, the diabetic group showed a significant correlation between fasting C-peptide and log ferritin (p = 0.001). In the control group, the fasting sugar level was significantly correlated with log ferritin (p = 0.034). These results suggest that serum ferritin can be employed as a marker of not only glucose homeostasis but also insulin resistance both in type 2 diabetic and control subjects.
Aged ; Body Mass Index ; C-Peptide/blood ; Carbohydrates/blood ; Diabetes Mellitus, Non-Insulin-Dependent/blood* ; Female ; Ferritin/blood* ; Human ; Male ; Middle Age ; Reference Values

BACKGROUND: It has been reported that many peripheral vasodilating drugs might improve insulin resistance. Cilostazol, a antithrombotic agent, increases peripheral blood flow in non-insulin dependent diabetic patients. The effect of cilostazol treatment on insulin resistance in streptozotocin (STZ)-induced non-insulin dependent diabetic Wistar rats was examined. METHODS: About a half of two-day old neonate siblings were injected intraperitoneally with STZ and maintained for six months, at which time they were compared with age-matched control rats for intraperitoneal glucose tolerance test (IPGTT) and for glucose infusion rate (GINF) in a euglycemic hyperinsulinemic glucose-clamp study. After that, these studies were also performed after feeding rat chow containing cilostazol (100 mg/kg/day) to rats with STZ-induced non-insulin dependent diabetes mellitus for four-weeks and compared with those of age-matched control rats. RESULTS: In the intraperitoneal glucose tolerance test studies, plasma glucose levels of STZ-induced non-insulin dependent diabetic rats were significantly higher and plasma insulin levels significantly lower than those of age-matched control rats in the age of six months. Glucose infusion rate was lower in STZ-induced non-insulin dependent diabetic rats than those of age-matched control rats. However, after a four-week cilostazol treatment, glucose infusion rate of STZ-induced non-insulin dependent diabetic rats was not significantly different from that of control rats. CONCLUSION: These findings suggested that cilostazol may improve insulin resistance in STZ-induced non-insulin dependent diabetic rats.
Animal ; Animals, Newborn ; Blood Glucose/*drug effects ; Comparative Study ; Diabetes Mellitus, Non-Insulin-Dependent/chemically induced/*drug therapy ; Disease Models, Animal ; Glucose Tolerance Test ; *Insulin Resistance ; Male ; Probability ; Rats ; Rats, Wistar ; Reference Values ; Sensitivity and Specificity ; Streptozocin ; Tetrazoles/*pharmacology ; Vasodilator Agents/*pharmacology