Diabetes & Metabolism Journal

Volume 24(6); December 2000

Original Articles

The Effect of Increased Beta Cell Mass on Glucose Tolerance in Rat.: Eun Sook Oh, Kun Ho Yoon, Sun Hee Seo, Sook Young Lee, Seung Hyun Ko, Won Young Lee, Sung Rae Kim, Moo Il Kang, Bong Yon Cha, Kwang Woo Lee, Ho Young Son, Sung Goo Kang; Korean Diabetes J. 2000;24(6):629-640. Published online January 1, 2001

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Abstract PDF: BACKGROUND
The aim of the present study is to evaluate the effect of increased beta cell mass by continuous 96-hour 50% glucose infusion on glucose tolerance in insulin resistance state induced by high fat diet in normal Sprague-Dawley rats. METHODS: The adult Sprague-Dawley rats weighing 200-250 gm were infused with 50% glucose or 0.45% saline via external jugular vein catheter for 96 hours. The both groups of rats were then randomly stratified into the two subgroups, and fed either high fat diet (54% of energy from fat) or normal rat chow (8.6% of energy from fat) for 4 weeks. On day 28, blood was collected for measuring the serum concentration of insulin, and oral glucose tolerance test (2 gm/kg body weight) was performed after overnight fasting. The beta cell mass was counted with the morphometric point-counting technique of Weibel. RESULTS: After the 96 hour infusion, the percentage of beta cell mass was significantly increased in glucose-infused rats when compared to the saline-infused group (p=0.03) and maintained up to day 28. Body weight gains were significantly greater in glucose infused rats than those of saline infused group (Increased value of weight : 142.9+/-15.2 g in glucose infused rats vs 125.3+/-21.1 g in saline infused rats, p=0.01). In the saline infusion-high fat diet group, the number of rats with impaired glucose tolerance was higher than those of other group (p<0.005). The glucose values at 90 minute and 120 minute were higher in saline infusion-high fat diet group than in glucose infusion-high fat diet group (p< 0.05). CONCLUSION: Our findings suggest that the increased beta cell mass has a favorable effect on glucose tolerance in insulin resistance state which were evoked by high fat diet.

Effects of High Fat Diet on Lipolysis in Skeletal Muscle and Adipose Tissue in Rats.: Chul Hee Kim, Yun Ey Chung, Seong Jin Lee, Joong Yeol Park, Sung Kwan Hong, Hong Kyu Kim, Kyo Il Suh, Ki Up Lee; Korean Diabetes J. 2000;24(6):641-651. Published online January 1, 2001

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Abstract PDF: BACKGROUND
It has been hypothesized that increased fat oxidation reduces glucose utilization in skeletal muscle, and is responsible for the insulin resistance associated with obesity or high-fat feeding. In contrast, there have been reports that fat oxidation capacity was decreased in skeletal muscles from insulin resistant subjects. This study was undertaken to examine whether insulin resistance in high- fat fed rats is associated with increased lipolysis in skeletal muscle and adipose tissue. METHODS: Two groups of Sprague-Dawley rats were fed either high-fat or low-fat diets for 4 weeks. Lipolysis in skeletal muscle and adipose tissue was determined by measurement of interstitial glycerol concentrations by a microdialysis method in basal and hyperinsulinemic-euglycemic clamp conditions. RESULTS: In basal state, plasma glycerol levels and interstitial glycerol concen trations of skeletal muscle, and adipose tissue were lower in high-fat fed than in low-fat fed rats. The degree of suppression of glycerol release by the hyperinsulinemia was smaller in the high-fat diet than in the low-fat diet group. However, plasma and interstitial glycerol concentrations during the hyperinsul inemic euglycemic clamps were also lower in the high-fat diet group. CONCLUSION: Lipolysis was decreased in skeletal muscle and adipose tissue of insulin resistant, high-fat fed rats. These results support the idea that limited fat oxidation capacity resulting in lipid accumulation in tissues, rather than increased fat oxida tion per se, is responsible for the insulin resistance associated with high-fat feeding.

Study on Role of Neutrophil in Endothelial Cell Injury under High Glucose Condition.: Seok Man Son, In Ju Kim, Yong Ki Kim; Korean Diabetes J. 2000;24(6):652-665. Published online January 1, 2001

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Abstract PDF: BACKGROUND
High glucose level plays a major role in the injury of endothelium during the early event in diabetic vascular complication. It was speculated that high glucose level may cause endothelial cell injury by neutrophil activation. METHODS: The human umbilical vein endothelial cells (HUVEC) were obtained from American Type Culture Collection. The cells were incubated as long as 24 hours to evaluate the expression of E-selectin on the cell surface using whole cell ELISA method. The adherence of neutrophils to human umbilical endothelial cell monolayers and transendothelial migration of 51Cr-labeled neutrophils were evaluated under the condition of different concentrations of D-glucose (5.5, 15, and 30 mmol/L). L-glucose (30 mmol/L) was used as an osmotic control after 24h incubation. We also measured neutrophil-mediated endothelial cell cytotoxicity using a 51Cr-release assay and release of activating markers (lactoferrin and myeloeroxidase) from neutrophils under the same conditions. RESULTS: The expression of E-selectin was increased on endothelium when incubated with medium containing high glucose (30 mmol/L) compared to control (5.5 mmol/L) preparation (1.36 OD vs. 0.79 OD, p<0.05). Increased adherence of neutrophils to HUVEC was observed with high glucose when compared to control (10.4% vs. 2.9%, p<0.01). Similarly, neutrophil migration across the cultured endothelial monolayers were also significantly increased by high glucose (49.8% vs. 27.3%, p<0.05). 51Cr-release from endothelial cells by neutrophils stimulated with high glucose was greater than that with control (27.5% vs. 10.6%, p<0.05). Release of activating markers from neutrophils incubated with high glucose was greater than that from neutrophils incubated with control. CONCLUSION: These results indicate that high glucose increases the adherence and transendothelial migration of neutrophils and cause endothelial cell injury through neutrophil activation. Thus, it is concluded that high glucose level maybe contribute to manifestation of the diabetic vascular disease, including the early step in the initiation of an acute inflammation of vascular endothelial cells.

Changes in the Amount and Function of Gi Protein in the Liver Cells of Streptozotocin-Induced Diabetic Rats.: Sun Myeong Ock, Hyun Shik Son, Oak Kee Hong, Jung Min Lee, Sung Rae Kim, Sang Ah Chang, Kun Ho Yoon, Moo Il Kang, Bong Yun Cha, Kwang Woo Lee, Ho Young Son, Sung Koo Kang; Korean Diabetes J. 2000;24(6):666-677. Published online January 1, 2001

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Abstract PDF: BACKGROUND
The functional and expressional changes of Gi proteins in diabetes have been investigated extensively, no agreement has been reached in the results. Moreover, studies using rats with different diabetic duration, and using subunits (Gialpha) of Gi proteins are lacking in literatures. Thus, we assessed the changes according to the duration of diabetes and examined the expressional changes of Gialphaand functional changes of Gi proteins in hepatocytes from streptozotocin-induced diabetic rats. METHODS: Male Sprague-Dawley rats were injected with streptozotocin to induce diabetes ; 1, 2, 3 and 5 weeks after the onset of diabetes, livers from the control and diabetic rats were fractionated into homogenate, interface, and plasma membrane. The levels of Gialpha1&2, Gialpha3 were quantified with western blots in each fraction. The functional changes of Gi proteins were evaluated by performing pertussis toxin-catalyzed ADP-ribosylation and measuring GTP S binding activity. RESULTS: 1) Gialpha2 and Gialpha3 were present mainly in the plasma membrane of hepatocytes in the diabetic and control rats, but the levels of these subunits were significantly higher in the diabetic rates than in the control rats (p<0.01). The levels of these subunits were not affected by the duration of diabetes. 2) In streptozotocin-induced diabetic rats, the levels of ADP-ribosylation of Gi proteins in liver plasma membranes decreased when pertussis toxin-catalyzed ADP-ribosylation was performed with liver tissues. However, the levels of these proteins were not affected by the duration of diabetes. 3) For the GTP S binding activity of Gi proteins in liver plasma membranes, the diabetic rats showed significantly less activity than the control rats (p<0.01). However, the activity was not affected by the duration of diabetes. The activity was somewhat restored by the insulin treatment of liver plasma membranes in diabetic rats. CONCLUSION: These results suggest that the insulin-deficient diabetic state induces the quantitative and functional changes in Gi proteins of hepatocytes regardless of the duration of diabetes. Therefore, these changes in Gi proteins may be the important compensatory reactions for the insulin resistance occurring in the insulin deficient state.

Randomized Controlled Trial

The Effect of Micronized Fenofibrate on the Plasma Levels of Glycated LDL-C, Lp(a) and Insulin Resistance in Patients with Type 2 Diabetes Mellitus.: Mi Kyoung Park, Duk Kyu Kim; Korean Diabetes J. 2000;24(6):678-688. Published online January 1, 2001

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It has been indicated that micronized fenofibrate therapy changes the atherogenic lipid profile into more favorable lipid profile in patients with type 2 diabetes and dyslipidemia. The aim of this study is to evaluate the effect of micronized fenofibrate on the plasma levels of glycated LDL-C, Lp(a), FFA and insulin resistance in patients with type 2 diabetes and dyslipidemia. METHODS: Forty-seven patients with type 2 diabetes (M/F=23/24, mean age 57 +/- 7 yrs) were studied who had relatively good glycemic index (HbA1c < 8.0%) but dyslipidemia (i.e., dyslipidemia : TG >2.25 mmol/L or HDL-C < 0.90 mmol/L or LDL-C >3.36 mmol/L). All the patients were maintained by the previous method of glucose control without change during entire period of the study. The patients were randomized to drug group (Lipidil ) or placebo group for 12 weeks and measured for fasting plasma levels of lipid, glycated LDL-C, Lp(a), insulin, C-peptide, glucose. The results were compared before and after the administration. RESULTS: Micronized fenofibrate therapy significantly reduced the plasma levels of triglyceride, total cholesterol, LDL-C, TC/HDL-C (p<0.0001), FFA (p<0.05) and ele vated the level of HDL-C (p<0.0001) after 12 weeks administration. However, no significant(-3.6%) changes were observed in the level of Lp(a) . In both groups, the plasma levels of glycated LDL-C were elevated even though the glycemic controls were good (drug group: 0.09+/-0.05 mmol/L, placebo group: 0.10+/-0.03 mmol/L), but no significant changes were noticed after administration for 12 weeks (-13.5%, +4.8%, respectively). HOMA-IR index was significantly decreased in the drug group after administration (p<0.01). The change of plasma insulin level was significantly different when compared to that of the placebo group (p<0.05). The plasma level of C-peptide and glycemic indexes (FBS and HbA1c) were not changed significant. CONCLUSION: Micronized fenofibrate therapy for 12 weeks was very effective for control of diabetic dyslipidemia. It significantly reduced FFA to improve the insulin resistance, but it didn't improve the elevated plasma level of glycated LDL-C and Lp(a).

Original Articles

The Serial Changes of Blood Glucose and Lipid Levels Following Allogeneic Bone Marrow Transplantation and Related Clinical Factors.: Won Young Lee, Moo Il Kang, Eun Sook Oh, Ki Won Oh, Hyun Shik Son, Kun Ho Yoon, Bong Yun Cha, Kwang Woo Lee, Ho Young Son, Sung Koo Kang, Wan Sik Shin, Woo Sung Min, Choon Choo Kim; Korean Diabetes J. 2000;24(6):689-698. Published online January 1, 2001

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Abstract PDF: BACKGROUND
In bone marrow transplantation (BMT), recipients are usually younger and immunosuppressants are open used in shorter period than in solid organ transplantation. Therefore, there might be a difference in glucose and lipid metabolism between BMT and solid organ transplantation. However, the serial changes of metabolic parameters following BMT have not been studied. There fore, the aim of this study is to investigate the serial changes of blood glucose, lipids and the putative factors that are related with these changes after BMT. METHODS: We have prospectively investigated 43 patients who underwent allogeneic BMT . Fasting plasma glucose (FPG), total cholesterol, triglyceride and high-density lipoprotein (HDL) were measured before BMT, and at 1, 2, 3, 4, 12 weeks and 6 months after BMT. The serial changes of these metabolic parameters according to clinical factors including type of BMT, mean daily steroid dosage, and occurrence of graft versus host disease (GVHD) were examined. RESULTS: 1. Mean FPG level increased during 4 weeks after BMT and remained above basal value at post-transplant 6 months. Total Cholesterol level was increased during initial 4 weeks after BMT and was above basal value at post-BMT of 3 and 6 months. Triglyceride level was progressively increased during initial 4 weeks after BMT, but returned to basal value thereafter. HDL-cholesterol level was significantly decreased during initial 4 weeks after BMT, but returned to basal value thereafter. 2. Patients with FPG above 126 mg/dL at post-transplant 6 months were 7 out of 43 patients (16%). Comparing patients with FPG above 126 mg/dL and the other patients, the former received larger amounts of daily steroid and had lower HDL-cholesterol level. 3. The changes of metabolic parameters were different according to type of BMT, steroid dose, and occurrence of GVHD. CONCLUSION: Although there was increase of FPG, TC, TG and decrease of HDL-C during initial 4 weeks after BMT, these metabolic changes recovered slowly thereafter. Immunosuppressants are thought to be associated with these changes. Further observation will be needed for the long-term effect of BMT on metabolic changes.

Free Testosterone and Sex Hormone-Binding Globulin Level in Type 2 Diabetic Men.: Ki Deuk Nam, Young Seol Kim, Cheol Young Park, Seung Joon Oh, Deog Yoon Kim, Jeong Taek Woo, Sung Woon Kim, In Myung Yang, Jin Woo Kim, Young Kil Choi; Korean Diabetes J. 2000;24(6):699-707. Published online January 1, 2001

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Abstract PDF: BACKGROUND
Insulin resistance is a risk factor for cardiovascular disease and type 2 diabetes mellitus. There are many previous studies indicating that insulin lowers serum sex hormone-binding globulin levels, and there is inverse correlation between insulin resistance and serum sex hormone-binding globulin levels in women. However, in men, a limited number of studies are available to explain the effect of sex hormone on age and insulin. Therefore, the present study was undertaken to investigate the relationship among free testosterone, hormone- binding globulin and age in type 2 diabetic men and control subjects. METHOD: Age, body mass index, total cholesterol, triglyceride, fasting blood sugar, and insulin concentrations were examined on 89 type 2 diabetic men and 47 control subjects. The free testosterone level was measured by commercially available double-antibody system (Radioimmunoassay). The sex hormone-binding globulin level was also measured by commercially available double-antibody system(Immunoradiometric assay). RESULTS: 1) Sex hormone-binding globulin level was significantly increased in patients with type 2 diabetes. However, there was no significant difference in free testosterone level between the two groups. 2) Sex hormone-binding globulin was positively correlated with age (r=0.4, p<0.001) in patients with type 2 diabetes. Sex hormone-binding globulin and free testos terone were not correlated with age in control sujects. 3) Free testosterone and sex hormone-binding globulin concentrations were not significantly related to serum insulin concentration after adjusting for age and body mass index. CONCLUSIONS: We observed increased sex hormone-binding globulin concentration in diabetes man, and was a positively related to age. Further studies are needed to understand the relationships between age, insulin resistance, testosterone, and sex hormone-binding globulin concentrations.

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