[Changes of plasma glucagon level in individuals with different glucose metabolism].

OBJECTIVE: To determine the levels of plasma glucagon and associated factors in individuals with different glucose metabolism. METHODS: One hundred and ten outpatient patients received an oral glucose tolerance test (OGTT) voluntarily. The patients were divided into three groups according to their OGTT results: normal glucose golerance (NGT) group (n=33), impaired glucose regulation (IGR) group (n=35), newly diagnosed type 2 diabetes (DM2) group (n=42). Plasma glucagon (GLC) and insulin (INS) at 0 min (0 h), 30 min (0.5 h), 60 min (1 h) and 120 min (2 h) were measured by radio immunity and electrochemiluminescence assay, respectively. We calculated the area of glucagon under the curve (AUCglc), the value of early phase glucagon secretion (deltaGLC = GLC(0.5 h) - GLC(0 h)) and the ratio of insulin to glucagon (INS/GLC). RESULTS: (1) There was no significant difference in the level of GLC(0 h) among the three groups (P > 0.05). (2) Patients in the IGR group had higher levels of GLC(0.5 h) and GLC(1 h), greater values of AUC(glc), and deltaGLC, and lower values of INS(0.5 h)/GLC(0.5 h) than those in the NGT group (P < 0.05). (3) Patients in the DM2 group had higher levels of GLC(0.5 h) and GLC(1 h), greater values of AUC(glc) and deltaGLC, and lower values of INS(0.5 h)/GLC(0.5 h) and INS(1 h)/GLC(1 h) than those in the NGT group (P < 0.05). (4) Patients in the DM2 group had higher levels of GLC(1 h), greater values of AUC(glc), and lower values of INS(0.5 h)/GLC(0.5 h), INS(1 h)/GLC(1 h), and INS(2 h)/GLC(2 h), than those in the IGR group (P < 0.05). (5) The multiple linear regression analysis showed that the value of AUC(glc). was positively correlated with HOMA-IR (adjust R2 = 0.219, P = 0.001). CONCLUSION: There are no significant differences in fasting plasma glucagon levels among the individuals with different glucose metabolism. Hypersecretion of glucagon and reduced glucagon suppressing effect of insulin occur in IGR patients, which is exacerbated when DM2 are developed. HOMA-IR is an important factor associated with glucagon hypersecretion.

[Change and correlated factors of fasting level of the plasma endotoxin in subjects with different glucose tolerances and body mass indices].

OBJECTIVE: To investigate the change of the levels of fasting plasma endotoxin (ET) and assess its correlated factors in individuals with different glucose tolerances and body mass indices. METHODS: The levels of fasting plasma ET were assayed by the endpoint chromogenic limulus amebocyte lysate method in subjects with type 2 diabetes (T2DM), impaired glucose regulation (IGR) and normal glucose tolerance (NGT). The height, body mass, waist, hips, systolic blood pressure and diastolic blood pressure were measured with the conventional methods; body mass index (BMI) and waist hip ratio (WHR) were calculated. All groups were divided into obesity (BMI>or=25 kg/m2) and non-obesity (BMI<25 kg/m2) subgroups. The levels of fasting blood glucose (FBG), 2 hours plasma glucose (2 hPG), fasting insulin (FINS), postprandial insulin (PINS), hemoglobin Alc (HbAlc), blood lipids, free fatty acids (FFA), serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also analyzed, and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. The relationship of the levels of plasma ET with age, BMI, WHR, blood pressure, FBG, 2 hPG, FINS, PINS, HOMA-IR, HbA1c, blood lipids, FFA, AST and ALT were also analyzed. RESULTS: (1) The levels of plasma ET in T2DM group (n=37) was significantly higher than that in NGT group (n=37) [7. 1 (3. 7-11. 8) EU/mL vs. 4. 5 (2.2-6.3) EU/mL, P<0.05]. The levels of plasma ET in IGR group (n=23) C5.0 (2.4-10.3) EU/mLU was lower than that in T2DM group and higher than NGT group but the differences were not significant (P>0. 05). (2) The levels of plasma ET in the obesity T2DM subgroup was higher than that in the non-obesity T2DM subgroup but the differences were not significant [7. 3 (3. 8-13. 3) EU/mL vs. 7.0 (3. 6-10. 4) EU/mL, P>0. 05]. There was a remarkable difference in the levels of plasma ET between obesity and non-obesity subgroup of IGR (6.8 (2.9-13.2) EU/mL vs. 2.7 (1.6-5. 5) EU/mL, P<0. 05), similarly between obesity and non-obesity subgroup of NGT (6.2 (3. 4-12. 7) EU/mL vs. 2. 8 (1. 8-4. 9) EU/mL, P<0. 05). (3) Multiple linear regression analysis demonstrated that ET wasn' t the important factor influencing FBG and 2 hPG. But BMI and FBG were the important factors influencing ET. 2 hPG and WHR weren't the important factors influencing ET. CONCLUSION: With the increase in glucose metabolic abnormalities and BMI, the levels of plasma ET are gradually increased. ET isn't the important factor influencing FBG and 2 hPG. BMI and FBG are the important factors in influencing ET.

[New perspectives in the treatment of diabetes by interfering with glucagon signaling pathway].

Glucagon, a hormone secreted from the alpha cell of the endocrine pancreas, is a major counterpart to insulin. After released into blood, glucagon will combine with its receptor in targeting tissues and form a compound, which then activates its signaling pathway, produces cAMP, promotes gluconeogenesis and glycogenolysis and inventually increases blood glucose. Researches recently display that it will be an important addition to treatment method by inhibiting synthesis and secretion of glucagon, neutralizing circulating glucagon, using glucagon receptor antagonists and prohibiting gene expression of glucagon receptor.

Frequent reoccurrence of hypoglycemia in a type 2 diabetic patient with insulin antibodies.

BACKGROUND: Insulin antibody (IAb) may be produced in patients receiving long-term, animal-derived insulin, leading to insulin resistance or hypoglycemia. There have been very few reports of hypoglycemia caused by IAb in patients taking recombinant human insulin. CASE REPORT: We report the case of an 82-year-old male patient with type 2 diabetes mellitus who suffered repeated episodes of severe hypoglycemia-related symptoms (including coma) prior to admission. The patient had been taking Novolin 30R, a premixed human insulin. The patient's IAb level was markedly elevated, and hypoglycemia caused by recombinant human insulin treatment-induced IAb production was diagnosed. Acarbose and metformin were prescribed, and the patient recovered uneventfully. The patient ceased taking these medications, and he was subsequently treated with recombinant human insulin to combat hyperglycemia. This was followed by reoccurrence of hypoglycemic coma. The patient was advised to avoid taking recombinant human insulin for the rest of his life and to control hyperglycemia with acarbose and metformin. CONCLUSIONS: Although rare, hypoglycemia caused by recombinant human insulin-induced IAb production should be considered in patients with type 2 diabetes who experience repeated episodes of hypoglycemia.

[The accuracy of combining aldosterone to renin ratio and low renin level in diagnosing primary aldosteronism].

OBJECTIVE: To evaluate the accuracy of combing serum aldosterone to plasma rennin ratio (ARR) and low renin level in diagnosing primary aldosteronism (PA). METHODS: The ratio of serum aldosterone to plasma renin was determined in 100 patients with PA and 61 patients with primary hypertension. The optimum cut-point of ARR was determined by the Receiver Operating Characteristic (ROC). The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and Youden index of the ARR at the optimum cut-off point were calculated in a separate test. The sensitivity and specificity of combining ARR and low renin level or high aldosterone level in diagnosing PA were determined. RESULTS: The supine ROC area under the curve (AUC1) was 0.991. The erect ROC area under the curve (AUC2) was 0.988. The AUC1 and AUC2 had no significant difference (P = 0.879). But they were both different significantly from with the area under the reference line (0.5) (P = 0.000). The optimum cut-off point of supine ARR was 112.06, with 0.96, 0.95, 0.91, 19.59 and 0.04 in sensitivity, specificity, Youden index, positive likelihood ratio and negative likelihood ratio, respectively. Combining ARR and low renin level produced a sensitivity and specificity of 0.422 and 0.998, respectively, in diagnosing PA. Combining ARR and high aldosterone level produced a sensitivity and specificity of 0.854 and 0.994, respectively in diagnosing PA. The optimum cut-off point of erect ARR was 36.61, with 0.99, 0.93, 0.92, 15 and 0.01 in sensitivity, specificity, Youden index, positive likelihood ratio and negative likelihood ratio, respectively. Combining ARR and low renin level produced a sensitivity and specificity of 0.941 and 0.986, respectively, in diagnosing PA. Combining ARR and high aldosterone level produced a sensitivity and specificity of 0.604 and 0.999, respectively in diagnosing PA. CONCLUSION: Erect ARR (> or = 36.61) can be used in detecting PA. Combining ARR and low renin level improves the accuracy in diagnosing PA and reduces misdiagnosis. The method is simple and available. It can be carried out in the out-patient department.

[Cytoskeleton and insulin related signal transduction pathways].

Cytoskeleton is a stereo wire frame system of filament, which is in a dynamic state. It can assemble or disassemble continuously with the change of physiological condition, and be regulated by many factors interior and exterior of the cell. Insulin is an important hormone involving in lots of physiological functions such as transport of glucose, gene expression and DNA synthesis. Normal secretion of insulin is the significant premise for which to educe its functions. Many studies indicate that cytoskeleton plays an important role in the process of insulin action and secretion, with a mechanism referring to insulin related signal transduction pathways tightly. The change of cytoskeleton influencing insulin related signal transduction pathways will lead to incidence of insulin resistance.

[Damage mechanism of intermittent exposure to high concentrations of glucose to beta cell lines (HIT-T15 cell)].

OBJECTIVE: To test the effect of intermittent exposure to high concentrations of glucose on HIT-T15 cells. METHODS: The HIT-T15 cells (pancreatic beta cell lines) were exposed to 16.7 mmol/L of glucose for two hours, at an interval of three hours. Such intermittent exposure was repeated three times a day. Otherwise, the cells were exposed to 5.5 mmol/L of glucose. The control groups included continuing exposure to 5.5 mmol/L of glucose (normal control group) and continuing exposure to 16.7 mmol/L of glucose. The impact of N-acetyl-L-cysteine (NAC) was also tested in the groups with intermittent and continuing exposure to 16. 7 mmol/L of glucose. The insulin was detected by radioimmunoassay (RIA). The mitochondrial membrane potential (MMP) was measured by laser scanning confocal microscope. The ATP levels of beta cells were examined by the luciferin-luciferase kit. The Malonaldehyde (MDA) was measured through thiobarbituric acid reaction (TBA). The intracellular reactive oxygen species (ROS) was observed by flow cytometry. RESULTS: The HIT-T15 cells exposed to intermittent and continuing high glucose secreted [(3.13 +/- 1.11) microIU/mLD and [(5.18 +/- 0. 95) microIU/mL] of insulin, significantly less than the control [(9.33 +/- 0.62) microIU/mL, P < 0.05]. The MDA and ROS levels increased while the ATP and MMP levels decreased significantly in the cells exposed to intermittent and continuing high glucose (P < 0.05). The cells exposed to intermittent high glucose produced more ROS than the cells exposed to continuing high glucose (P < 0.05). CONCLUSION: Exposure of HIT-T15 to high glucose leads to oxidative stress of mitochondrial. Intermittent exposure causes more serious stress than continuing exposure. Such response might be a result of decreased MMP level and ATP contents.

[The effect of metformin on insulin receptor protein tyrosine kinase activity of HIT-T15 cell exposed to high concentration glucose and free fatty acid].

OBJECTIVE: To study the effect of metformin on insulin receptor (IRc) protein tyrosine kinase (PTK) activity of HIT-T15 cell exposed to high glucose and free fatty acid (FFA) concentration, and to explore the mechanism of metformin (MF) improving beta cell insulin resistance. METHODS: HIT-T15 cells were incubated for 48 h in a medium containing 5.5-16.7 mmol/L glucose and 0.5 mmol/L palmitic acid respectively. The cells were re-incubated for another 24 h with or without 2.5 microg/mL MF. The PTK activities of IRc were measured by radioactive enzyme assay. RESULTS: The enzymatic activities of IRc PTK were significantly decreased to HIT-T15 cells having the exposure to high glucose or high FFA concentration, when compared to control [(52.5 +/- 18.6) or (54.6 +/- 14.0) vs. (119.4 +/- 29.1) pmol/(min x microg), P < 0.01 respectively. The enzymatic activities of IRc PTK in HIT-T15 cells reincubated with 2.5 microg/mL MF for an additional 24 h were significantly increased vs MF free group [(113.0 +/- 29.8) vs. (52.5 +/- 18.6) pmol/(min x microg), x 98.6 +/- 26.1) vs. (54.6 +/- 14.0) pmol/(min x microg), P < 0.01 respectively], and were no significant difference in comparison with control group (P > 0.05). CONCLUSION: The enzymatic activities of IRc PTK are significantly decreased in HIT-T15 cells chronically exposed to elevated glucose or free fatty acids levels. Metformin can restore approximately normal enzymatic activities of PTK of HIT-T15 cells, of which the PTK activities have been impaired by chronic exposure to high glucose or free fatty acids levels.