Comparative pharmacodynamic and pharmacokinetic characteristics of subcutaneous insulin glulisine and insulin aspart prior to a standard meal in obese subjects with type 2 diabetes.

AIMS: A multinational, randomized, double-blind, two-way crossover trial to compare the pharmacokinetic and pharmacodynamic properties of bolus, subcutaneously administered insulin glulisine (glulisine) and insulin aspart (aspart) in insulin-naÏve, obese subjects with type 2 diabetes. METHODS: Thirty subjects [9/21 females/males; mean ± SD age: 60.7 ± 7.7 years; body mass index (BMI): 33.5 ± 3.3 kg/m(2) ; duration of diabetes: 6.8 ± 4.6 years; HbA1c: 7.1 ± 0.8%] were included in the analysis. They fasted overnight and then received a 0.2 U/kg subcutaneous dose of glulisine or aspart 2 min before starting a standardized test meal, 7 days apart, according to a randomization schedule. Blood samples were taken every 15 min, starting 20 min before the meal and ending 6 h postprandially. RESULTS: The area under the absolute glucose concentration-time curve between 0 and 1 h after insulin injection and maximal glucose concentration was significantly lower with glulisine than with aspart (p = 0.0455 and 0.0337, respectively). However, for the total study period, plasma glucose concentration was similar for glulisine and aspart. Peak insulin concentration was significantly higher for glulisine than for insulin aspart (p < 0.0001). Hypoglycaemic events (≤ 70 mg/dl with or without symptoms) occurred in 13 and 16 subjects treated with glulisine and aspart, respectively, but there were no cases of severe hypoglycaemia requiring intervention. CONCLUSIONS: Glulisine was associated with lower glucose levels during the first hour after a standard meal; the remaining glucose profiles were otherwise equivalent, with higher insulin levels observed throughout the study period.

Kinetics of prebeta1 HDL and alphaHDL in type II diabetic patients.

BACKGROUND: The aim of this study was to analyze the recycling of high density lipoprotein (HDL) in six type II diabetic patients compared with six control subjects by endogenous labelling of apolipoprotein A-I (Apo A-I) with stable isotope Apo A. MATERIALS AND METHODS: The -I-HDL kinetics were performed by infusion of (5.5.5-(2)H3)-leucine for 14 h. The prebeta1 and alphaHDL were separated by gel filtration fast protein liquid chromatrography system (FPLC). Kinetics of isotopic enrichment of Apo A-I were analyzed with a multi-compartmental model software (SAAM II, SAAM Institute, Seattle, WA). RESULTS: Plasma Apo A-I concentration was decreased in patients with type II diabetes as a result of a decrease in Apo A-I-alphaHDL (P < 0.05). Diabetic patients were also characterized by an increased relative contribution of Apo A-I in prebeta1 HDL (18.3 +/- 2.8% vs 11.9 +/- 3.7%, P < 0.01). The synthetic rate of prebeta1 HDL was slightly increased in diabetic patients compared with control (NS) and an increase of recycling rate of alpha to prebeta1 HDL was observed (11.67 +/- 3.14 d(-1) vs 7.09 +/- 4.51 d(-1), P < 0.05). The clearance rate of Apo A-I was higher in diabetic patients (P < 0.05 for Apo A-I-prebeta1 HDL and P < 0.005 for Apo A-I-alphaHDL). CONCLUSION: This study suggests that the usual increase in prebeta1 HDL in type II diabetic patients is mainly related to an increased conversion rate of alpha to prebeta1 HDL.

Colonic fermentation from lactulose inhibits lipolysis in overweight subjects.

One of the strategies to prevent insulin resistance is to reduce circulating free fatty acids (FFA). The aim of this study is to assess the effect of an oral lactulose load on fatty acid metabolism in overweight subjects. Eight overweight subjects received a primed constant intravenous infusion of [1-(13)C]acetate and of [1,1,2,3,3-(2)H(5)]glycerol for 9 h. After 3 h of tracer infusion, patients ingested 30 g lactulose, or saline solution. Arterialized blood samples were collected every 20 min. Basal plasma concentrations of acetate were similar before and between oral treatments as well as glycerol and FFA concentrations. Plasma acetate turnover was 11.4 +/- 2.4 vs. 10.7 +/- 1.4 micromol.kg(-1).min(-1) [not significant (NS)], and plasma glycerol turnover was 3.8 +/- 0.4 vs. 4.8 +/- 1.9 micromol.kg(-1).min(-1) (NS). After lactulose ingestion, acetate concentration increased twofold and then decreased to baseline. Acetate turnover rate increased to 15.5 +/- 2.2 micromol.kg(-1).min(-1) after lactulose treatment, whereas it was unchanged after saline treatment (10.3 +/- 2.2 micromol.kg(-1).min(-1), P < or = 0.0001). In contrast, FFA concentrations decreased significantly after lactulose ingestion and then increased slowly. Glycerol turnover decreased after lactulose ingestion compared with saline, 2.8 +/- 0.4 vs. 3.5 +/- 0.3 micromol.kg(-1).min(-1) (P < or = 0.05). A significant negative correlation was found between glycerol and acetate turnover after lactulose treatments (r = -0.78, P < or = 0.02). These results showed in overweight subjects a short-term decrease in FFA level and glycerol turnover after lactulose ingestion related to a decrease of lipolysis in close relationship with an increase of acetate production.

Influence of atorvastatin on apolipoprotein E and AI kinetics in patients with type 2 diabetes.

Atorvastatin reduces both plasma cholesterol and triglyceride concentrations in patients with type 2 diabetes, but mechanisms underlying triglyceride decrease and the effect of atorvastatin on high density lipoprotein (HDL) still remain unclear. Apolipoprotein (apo) E plays a crucial role in modulating production and clearance of triglyceride-rich very low density lipoprotein (VLDL). The main effect of apoAI is to modulate HDL metabolism. The aim of this work was to study the influence of atorvastatin on apoAI and apoE kinetics and to determine whether its hypocholesterolemic and hypotriglyceridemic effects could be related to changes in this apolipoprotein metabolism. Plasma VLDL-apoE, HDL-apoE, and HDL-apoAI were studied in seven patients with diabetes with mixed hyperlipidemia using a stable isotope labeling technique ([(2)H3]leucine-primed constant infusion) and monocompartmental model before and after 2 months of treatment with 40 mg/day of atorvastatin. Plasma apoE concentration was significantly reduced (44.1 +/- 19.1 versus 32 +/- 11.6 mg/l, p < 0.05) after treatment. This decrease was associated with a diminution of HDL-apoE concentration (17.46 +/- 6.71 versus 13.37 +/- 6.05 mg/l, p < 0.05) and production rate (0.202 +/- 0.085 versus 0.119 +/- 0.047 mg/kg/day, p < 0.05), whereas an increase in VLDL-apoE concentration (6.44 +/- 2.16 before versus 9.23 +/- 4.02 mg/l after, p < 0.05) and production rate (0.827 +/- 0.367 versus 1.524 +/- 0.664 mg/kg/day, p < 0.05) was observed. No significant difference was observed after treatment for apoAI parameters. We conclude that atorvastatin treatment promotes different apoE distribution between HDL and VLDL, favoring VLDL apoE content. The increased number of apoE per VLDL particle suggests that atorvastatin could enhance the direct catabolism of triglyceride-rich VLDL through apoE receptor pathways.

New model for kinetic studies of HDL metabolism in humans.

BACKGROUND: The aim of the study was to develop a new model for kinetic studies of Apolipoprotein A-I of HDL (Apo A-I-HDL) labelled with stable isotope by using HDL subclasses isolated with fast protein liquid chromatography (FPLC). MATERIALS AND METHODS: Apo A-I-HDL kinetics were studied by infusing [5.5.5-(2)H(3)]-leucine for 14 h in six healthy subjects. Prebeta(1) and alphaHDL were separated by FPLC and total HDL by ultracentrifugation (HDL-UC). RESULTS: The tracer-to-tracee ratios were higher in prebeta(1) HDL than in HDL-UC or alphaHDL. Leucine enrichments found in HDL-UC were higher compared with alphaHDL, suggesting that HDL-UC were composed of a mixture of Apo A-I-alphaHDL and Apo A-I-prebeta(1) HDL. Kinetic analysis of data obtained from FPLC was achieved using a multicompartmental model, including a conversion between prebeta(1) and alphaHDL compartments. The production rate of prebeta(1) HDL was 7.72 +/- 2.86 mg kg(-1) d(-1) (mean +/- SD). Prebeta(1) HDL were converted to alphaHDL at a rate of 96.24 +/- 42.99 pool d(-1), and the synthesis rate of prebeta(1) HDL from alphaHDL was 10-fold slower: 7.09 +/- 4.51 pool d(-1). Apo A-I-FCR of HDL-UC was estimated using a one-compartment model (0.165 +/- 0.074 pool d(-1)), and was higher but not significantly compared with FCR of Apo A-I-alphaHDL (0.112 +/- 0.026 pool d(-1)) calculated with the new model. CONCLUSIONS: This study reports for the first time a model involving enrichments of Apo A-I in prebeta(1) and alphaHDL which allowed the measure of Apo A-I cycling within HDL fraction and will aid better understanding of kinetics of HDL in humans.

Postprandial changes in the distribution of apolipoprotein AIV between apolipoprotein B- and non apolipoprotein B-containing lipoproteins in obese women.

Plasma apolipoprotein AIV (apo AIV) level has been shown to be a good marker of triglyceride changes after a high-fat diet. However, the distribution of apo AIV between apo B- and non-apo B-containing lipoproteins (Lp) during the postprandial state has not been described as well as the influence of obesity on this distribution. Our aim was to study the influence of parameters related to obesity and insulin resistance on the postprandial changes in apo AIV-containing Lp after a high-fat meal in obese women. Twenty-three overweight or obese women (body mass index [BMI] ranging from 29.1 and 64.0 kg.1 m(-2)), for whom blood samples were taken after fasting overnight, participated in the study. Thirteen of these obese women were given a fatty meal and, in this case, blood samples were taken at fast and 30 minutes, 1, 2, 4, and 6 hours after ingestion of the fat meal. Apo AIV-containing particle families, Lp B:AIVf (family [f] of particles containing at least apo B and apo AIV) and Lp AIV non-Bf (family [f] of particles containing apo AIV, but free of apo B) were quantified by sandwich enzyme-linked immunosorbent assay (ELISA). When fasting, Lp B:AIVf and Lp AIV non-Bf did not correlate with any of the parameters related to obesity and insulin resistance, if one excepts a positive correlation between HDL-cholesterol (HDL-C) and Lp AIV non-Bf. Postprandial lipemia was associated with a trend towards an increase in the plasma levels of apo AIV-containing Lp 6 hours after fat ingestion. The postprandial peak of Lp B:AIVf and Lp AIV non-Bf occurred 2 hours after the triglyceride peak. The distribution between apo B- and non-apo B-containing Lp did not change after ingestion of the fat meal, if one excepts a tendancy towards a lower ratio of bound and nonbound forms at 8 hours. Fasting plasma Lp B:AIVf concentration correlated with the area under the curve (AUC) of plasma triglycerides (beta = 0.11, P <.02). In a multivariate analysis, BMI (beta = 51.85, P <.001), fasting triglycerides (beta = 431.08, P <.01), and low-density lipoprotein-cholesterol (LDL-C) (beta = 2638.57, P <.005) were independent and positive determinants of the AUC of Lp AIV non-Bf, while waist circumference (beta = -23.94, P <.001), cholesterol (beta = -1655.02, P <.01), and systolic blood pressure (beta = -6.34, P <.05) were negative and independent determinants of this AUC. Fasting Lp B:AIVf may represent a good marker of the postprandial triglyceride increase in obese women. Changes in apo AIV concentrations in apo B- and non-apo B-containing Lp after a fat meal depend mainly on the degree of obesity rather than on insulin resistance. This effect is more obvious for Lp AIV non-Bf than for Lp B:AIVf.

Insulin effects on acetate metabolism.

Acetate metabolism was studied in patients with insulin resistance. To evaluate the interaction between glucose and acetate metabolism, we measured acetate and glucose turnover with a hyperinsulinemic euglycemic clamp (hot clamp) in obese and diabetic patients with insulin resistance (n = 8) and in a control group with normal insulin sensitivity (n = 6). At baseline, acetate turnover and plasma concentrations were similar between the two groups (group means: 4.3 +/- 0.4 micromol x kg-1 x min-1 and 128.2 +/- 11.1 micromol/l). Acetate concentrations decreased in both groups with hyperinsulinemia but were significantly lower in the insulin-resistant group (20% vs. 12%, P < 0.05). After the hot clamp treatment, acetate turnover increased for the two groups and was higher in the group with normal insulin sensitivity: 8.1 +/- 0.7 vs. 5.5 +/- 0.5 micromol x kg-1 x min-1 (P < 0.001). No change related to insulin action was observed in either group in the percentage of acetate oxidation. This was approximately 70% of overall utilization at baseline and during the clamp. No correlation between glucose and acetate utilization was observed. Our results support the hypothesis that, like glucose metabolism, acetate metabolism is sensitive to insulin.

Apolipoprotein E kinetics: influence of insulin resistance and type 2 diabetes.

BACKGROUNDS AND AIMS: Insulin resistance related to obesity and diabetes is characterized by an increase in plasma TG-rich lipoprotein concentrations. Apolipoprotein (apo) E plays a crucial role in the metabolism of these lipoproteins and particularly in the hepatic clearance of their remnants. The aim of this study was to explore apoE kinetics of obese subjects and to determine what parameters could influence its metabolism. METHODS: Using stable-isotope labelling technique ([(2)H(3)]-leucine-primed constant infusion) and monocompartmental model (SAAM II computer software), we have studied the plasma kinetics of very-low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) apoE in 12 obese subjects (body mass index (BMI) 27.4-36.6 kg/m(2)): Seven were type 2 diabetics (age 47-65 y; HbA1c 7.1-10.2%) and five were non-diabetics (age 40-51 y, HbA1c: 4.9-5.3%). Six of the diabetic subjects were insulin resistant as assessed by insulin sensitivity index (HOMA 2.6-10.0), while non-diabetic subjects were all insulin sensitive (HOMA 1.2-2.1). RESULTS: Plasma VLDL and HDL apoE concentrations were significantly higher in diabetic than in non-diabetic subjects (5.74+/-1.60 vs 1.46+/-1.74 mg/l, P<0.01 and 17.81+/-6.67 vs 9.97+/-3.32 mg/l, P<0.05). These increased levels were associated with significantly higher absolute production rate (APR) of VLDL and HDL apoE (0.714+/-0.343 vs 0.130+/-0.200 mg/kg/day, P<0.01, and 0.197+/-0.087 vs 0.080+/-0.060 mg/kg/day, P<0.05, respectively) while no significant difference was found for fractional catabolic rate (FCR) of VLDL and HDL apoE (3.44+/-1.64 vs 1.97+/-0.84/day and 0.30+/-0.12 vs 0.19+/-0.09/day, respectively). In the whole population, BMI was not correlated with any of apoE kinetic data. HOMA was positively correlated with FCR of VLDL apoE (r=0.64, P<0.05) and tended to be correlated with APR of VLDL apoE (r=0.58, P=0.06). HbA1c was positively correlated with APR and FCR of both VLDL apoE (r=0.91 and 0.78, P<0.01, respectively) and HDL apoE (r=0.66 and 0.69, P<0.05, respectively). CONCLUSION: Obese diabetics are characterized by elevated VLDL and HDL apoE levels associated with enhancement of VLDL and HDL apoE production rates. Whereas obesity did not influence apoE kinetic parameters in itself, insulin resistance may lead to an increase in VLDL apoE production and fractional catabolic rates. Diabetes and the glycemic control may also specifically influence the kinetics of both VLDL and HDL apoE. All together, these disorders should explain at least part of the increase in VLDL and HDL apoE observed in diabetes.

Effect of low-density lipoproteins on apolipoprotein AI kinetics in heterozygous familial hypercholesterolemia.

In patients with heterozygous familial hypercholesterolemia (FH), both synthetic and clearance rates of high-density lipoproteins (HDL) are increased compared with control subjects. According to in vitro data on hepatocytes, the expanded pool size of low-density lipoproteins (LDL) in FH could partly explain the enhanced HDL production. Therefore, we have tested the hypothesis that a reduction of LDL pool size, achieved by LDL-apheresis, is associated with a downregulation of HDL synthesis. We studied the kinetics of HDL by infusing [5,5,5-(2)H(3)]-leucine in 7 heterozygous FH patients before and after 3 biweekly LDL-apheresis using dextran sulfate columns. Both plasma and LDL-cholesterol levels were decreased after LDL-apheresis (169 +/- 35 v 422 +/- 27 mg/dL, P <.05, and 85 +/- 19 v 327 +/- 52 mg/dL, P <.05, respectively). Plasma triglyceride level was unaffected (162 +/- 43 v 176 +/- 35 mg/dL, not significant [NS]) and HDL composition remained stable (HDL-cholesterol 29 +/- 6 v 37 +/- 7 mg/dL, NS, and HDL-triglyceride 20 +/- 6 v 19 +/- 8 mg/dL, NS). Plasma apolipoprotein AI (apo AI) was also similar (122 +/- 20 v 115 +/- 18 mg/dL, NS). Mean HDL-apo AI fractional catabolic rate (FCR) was slightly higher (0.41 +/- 0.07 v 0.36 +/- 0.14 pool/d, NS), and absolute production rate (APR) was increased (22.1 +/- 5.7 v 18.0 +/- 5.7 mg/kg/d, P <.05) after LDL-apheresis. These human kinetic data suggest that LDL do not play a major role on HDL production in heterozygous FH patients.

In vivo evidence for the role of lipoprotein lipase activity in the regulation of apolipoprotein AI metabolism: a kinetic study in control subjects and patients with type II diabetes mellitus.

The aim of this study was to delineate the role of lipoprotein lipase (LPL) activity in the kinetic alterations of high density lipoprotein (HDL) metabolism in patients with type II diabetes mellitus compared with controls. The kinetics of HDL were studied by endogenous labeling of HDL apolipoprotein AI (HDL-apo AI) using a primed infusion of D(3)-leucine. The HDL-apo AI fractional catabolic rate (FCR) was significantly increased (0.32 +/- 0.07 vs. 0.23 +/- 0.05 pool/day; P < 0.01), and HDL composition was changed [HDL cholesterol, 0.77 +/- 0.16 vs. 1.19 +/- 0.37 mmol/L (P < 0.05); HDL triglycerides, 0.19 +/- 0.12 vs. 0.10 +/- 0.03 mmol/L (P < 0.05)] in diabetic patients compared with healthy subjects. HDL-apo AI FCR was correlated to plasma and HDL triglyceride concentrations (r = 0.82; P < 0.05 and r = 0.80; P < 0.05, respectively) and to homeostasis model assessment (r = 0.78; P < 0.05). Postheparin plasma LPL activity was decreased in type II diabetes (6.8 +/- 2.8 vs. 18.1 +/- 5.2 micromol/mL postheparin plasma.h; P < 0.005) compared with that in healthy subjects and was correlated to the FCR of HDL-apo AI (r = -0.63; P < 0.05). LPL activity was also correlated with HDL cholesterol (r = 0.78; P < 0.05), plasma and HDL triglycerides (r = -0.87; P < 0.005 and r = -0.83; P < 0.05, respectively), and homeostasis model assessment (r = -0.79; P < 0.05). In addition, the LPL to hepatic lipase ratio was correlated with the catabolic rate of HDL (r = -0.76; P < 0.06). These results suggest that a decrease in the LPL to hepatic lipase ratio in type II diabetes mellitus, mainly related to lowered LPL activity, could induce an increase in HDL catabolism. These alterations in HDL kinetics in type II diabetes proceed to some extent from changes in their composition, probably linked to an increase in triglyceride transfer from very low density lipoprotein particles, in close relationship with LPL activity and resistance to insulin.

Negative and independent influence of apolipoprotein E on C-reactive protein (CRP) concentration in obese adults. Potential anti-inflammatory role of apoE in vivo.

BACKGROUND: Obesity is frequently associated with an increase in the early inflammation marker C-reactive protein (CRP), insulin resistance and changes in lipoprotein metabolism. Increased CRP is known as an independent cardiovascular risk factor. Since the apolipoproteins (apo) E and CIII components of HDL are associated with reduced cardiovascular risk and since apoE has in vitro anti-inflammatory effect, we have investigated the relationships between apoE, apoCIII (in apoB and non apoB containing lipoproteins) and CRP in obese adults. METHODS: The following parameters from 34 healthy obese fasting women (age 22-64 y, body mass index (BMI) 28-68 kg/m2) were measured: (1) ApoE and apoCIII, in total plasma, in apoB- (E LpB, CIII LpB) and non-apoB-containing lipoproteins (E LpnonB, CIII LpnonB); (2) CRP and cytokine secreted by adipose tissue (TNF-alpha and its soluble receptor TNFR2); (3) triglyceride, HDL-cholesterol, systolic blood pressure, diastolic blood pressure, waist and hip circumferences, insulin, glucose. HOMA, a marker of insulin sensitivity, and the ratio E/CIII in LpB and LpnonB were calculated. RESULTS: CRP was positively correlated with BMI (P<0.05), waist circumference (WC, P<0.05), triglyceride (P<0.05) and negatively correlated with apoE (P<0.01) and E LpnonB (P<0.05). Two multiple regression models including parameters related to CRP with a P<0.25 were run stepwise to assess their independent contribution to CRP concentration. In the first model (including BMI, WC, HOMA, insulin, triglyceride, apoE, E LpnonB), apoE was the best predictor of CRP (P=0.01) together with triglyceride (P=0.02) and BMI (P=0.08). The second model took into account E/CIII LpnonB ratio with the parameters included in the first model. In this second model, E/CIII LpnonB was the best predictor of CRP (P=0.007), explaining 39% of CRP variance. CONCLUSION: ApoE is strongly correlated with CRP and could have an anti-inflammatory effect in vivo in obese subjects. This correlation could be limited to LpnonB lipoproteins, depending on their apoE and CIII relative content.