Leucine-enriched essential amino acid supplementation in mechanically ventilated trauma patients: a feasibility study.

BACKGROUND: Critically ill patients lose up to 2% of muscle mass per day. We assessed the feasibility of administering a leucine-enriched essential amino acid (L-EAA) supplement to mechanically ventilated trauma patients with the aim of assessing the effect on skeletal muscle mass and function. METHODS: A randomised feasibility study was performed over six months in intensive care (ICU). Patients received 5 g L-EAA five times per day in addition to standard feed (L-EAA group) or standard feed only (control group) for up to 14 days. C-reactive protein, albumin, IL-6, IL-10, urinary 3-MH, nitrogen balance, protein turnover ([1-13C] leucine infusion), muscle depth change (ultrasound), functional change (Katz and Barthel indices) and muscle strength Medical Research Council (MRC) sum score to assess ICU Acquired Weakness were measured sequentially. RESULTS: Eight patients (9.5% of screened patients) were recruited over six months. L-EAA doses were provided on 91/124 (73%) occasions. Inflammatory and urinary marker data were collected; serial muscle depth measurements were lacking due to short length of stay. Protein turnover studies were performed on five occasions. MRC sum score could not be performed as patients were not able to respond to the screening questions. The Katz and Barthel indices did not change. L-EAA delivery was achievable, but meaningful functional and muscle mass outcome measures require careful consideration in the design of a future randomised controlled trial. CONCLUSION: L-EAA was practical to provide, but we found significant barriers to recruitment and measurement of the chosen outcomes which would need to be addressed in the design of a future, large randomised controlled trial. TRIAL REGISTRATION: ISRCTN Registry, ISRCTN79066838 . Registered on 25 July 2012.

Measurement of hepatic insulin sensitivity early after the bypass of the proximal small bowel in humans.

OBJECTIVE: Unlike gastric banding or sleeve gastrectomy procedures, intestinal bypass procedures, Roux-en-Y gastric bypass in particular, lead to rapid improvements in glycaemia early after surgery. The bypass of the proximal small bowel may have weight loss and even caloric restriction-independent glucose-lowering properties on hepatic insulin sensitivity. In this first human mechanistic study, we examined this hypothesis by investigating the early effects of the duodeno-jejunal bypass liner (DJBL; GI Dynamics, USA) on the hepatic insulin sensitivity by using the gold standard euglycaemic hyperinsulinaemic clamp methodology. METHOD: Seven patients with obesity underwent measurement of hepatic insulin sensitivity at baseline, 1 week after a low-calorie liquid diet and after a further 1 week following insertion of the DJBL whilst on the same diet. RESULTS: Duodeno-jejunal bypass liner did not improve the insulin sensitivity of hepatic glucose production beyond the improvements achieved with caloric restriction. CONCLUSIONS: Caloric restriction may be the predominant driver of early increases in hepatic insulin sensitivity after the endoscopic bypass of the proximal small bowel. The same mechanism may be at play after Roux-en-Y gastric bypass and explain, at least in part, the rapid improvements in glycaemia.

Exercise Training Reduces Liver Fat and Increases Rates of VLDL Clearance But Not VLDL Production in NAFLD.

CONTEXT: Randomized controlled trials in nonalcoholic fatty liver disease (NAFLD) have shown that regular exercise, even without calorie restriction, reduces liver steatosis. A previous study has shown that 16 weeks of supervised exercise training in NAFLD did not affect total very low-density lipoprotein (VLDL) kinetics. OBJECTIVE: The objective of the study was to determine the effect of exercise training on intrahepatocellular fat (IHCL) and the kinetics of large triglyceride (TG)-rich VLDL1 and smaller denser VLDL2, which has a lower TG content. DESIGN: This was a 16-week randomized controlled trial. PATIENTS: A total of 27 sedentary patients with NAFLD participated in the trial. INTERVENTION: The intervention was composed of supervised exercise with moderate-intensity aerobic exercise or conventional lifestyle advice (control). MAIN OUTCOME: VLDL1 and VLDL2-TG and apolipoprotein B (apoB) kinetics were investigated using stable isotopes before and after the intervention. RESULTS: In the exercise group, maximal oxygen uptake increased by 31% ± 6% (mean ± SEM) and IHCL decreased from 19.6% (14.8%, 30.0%) to 8.9% (5.4%, 17.3%) (median [interquartile range]) with no significant change in maximal oxygen uptake or IHCL in the control group (change between groups, P < .001 and P = .02, respectively). Exercise training increased VLDL1-TG and apoB fractional catabolic rates, a measure of clearance, (change between groups, P = .02 and P = .01, respectively), and VLDL1-apoB production rate (change between groups, P = .006), with no change in VLDL1-TG production rate. Plasma TG did not change in either group. CONCLUSION: An increased clearance of VLDL1 may contribute to the significant decrease in liver fat after 16 weeks of exercise in NAFLD. A longer duration or higher-intensity exercise interventions may be needed to lower the plasma TG and VLDL production rate.

Exercise-induced improvements in liver fat and endothelial function are not sustained 12 months following cessation of exercise supervision in nonalcoholic fatty liver disease.

Supervised exercise reduces liver fat and improves endothelial function, a surrogate of cardiovascular disease (CVD) risk, in nonalcoholic fatty liver disease (NAFLD). We hypothesised that after a 16-week supervised exercise program, patients would maintain longer-term improvements in cardiorespiratory fitness, liver fat and endothelial function. Ten NAFLD patients (5/5 males/females, age 51±13 years, body mass index 31±3 kg m-2 (mean±s.d.)) underwent a 16-week supervised moderate-intensity exercise intervention. Biochemical markers, cardiorespiratory fitness (VO2peak), subcutaneous, visceral and liver fat (measured by magnetic resonance imaging and spectroscopy respectively) and brachial artery flow-mediated dilation (FMD) were assessed at baseline, after 16 weeks of supervised training and 12 months after ending supervision. Despite no significant change in body weight, there were significant improvements in VO2peak (6.5 ml kg-1 min-1 (95% confidence interval 2.8, 10.1); P=0.003), FMD (2.9% (1.5, 4.2); P=0.001), liver transaminases (P<0.05) and liver fat (-10.1% (-20.6, 0.5); P=0.048) immediately after the 16-week supervised training. Nevertheless, 12 months after ending supervision, VO2peak (0.9 ml kg-1 min-1 (-3.3, 5.1); P=0.65), FMD (-0.07% (-2.3, 2.2); P=0.95), liver transaminases (P>0.05) and liver fat (1.4% (-13.0, 15.9); P=0.83) were not significantly different from baseline. At 12 months following cessation of supervision, exercise-mediated improvements in liver fat and other cardiometabolic variables had reversed with cardiorespiratory fitness at baseline levels. Maintenance of high cardiorespiratory fitness and stability of body weight are critical public health considerations for the treatment of NAFLD (Clinicaltrials.gov identifier: NCT01834300).

Effect of subcutaneous insulin detemir on glucose flux, lipolysis and electroencephalography in type 1 diabetes.

The aim of the present study was to investigate the effects of subcutaneous detemir on glucose flux, lipid metabolism and brain function. Twelve people with type 1 diabetes received, in random order, 0.5 units/kg body weight detemir or NPH insulin. Glucose concentration was clamped at 5 mmol/l then increased to 10 mmol/l. Glucose production rate (glucose Ra), glucose uptake (glucose Rd) and glycerol production (glycerol Ra) were measured with a constant intravenous infusion of [6,6(2) H(2)]glucose and [(2)H(5)]glycerol. Electroencephalography direct current (DC) and alternating current (AC) potentials were measured. While detemir induced similar effects on glucose Ra, glucose Rd and glycerol Ra during euglycaemia compared with NPH, it triggered a distinct negative shift in DC potentials, with a significant treatment effect in frontal cerebrocortical channels (p < 0.001). AC spectral power showed significant differences in theta and alpha frequencies during euglycaemia (p = 0.03). Subcutaneous detemir exerts different effects on brain function when compared with NPH in people with type 1 diabetes. This may be an important mechanism behind the limitation of weight gain with detemir.

Safety, efficacy and glucose turnover of reduced prandial boluses during closed-loop therapy in adolescents with type 1 diabetes: a randomized clinical trial.

AIMS: To evaluate safety, efficacy and glucose turnover during closed-loop with meal announcement using reduced prandial insulin boluses in adolescents with type 1 diabetes (T1D). METHODS: We conducted a randomized crossover study comparing closed-loop therapy with standard prandial insulin boluses versus closed-loop therapy with prandial boluses reduced by 25%. Eight adolescents with T1D [3 males; mean (standard deviation) age 15.9 (1.5) years, glycated haemoglobin 74 (17) mmol/mol; median (interquartile range) total daily dose 0.9 (0.7, 1.1) IU/kg/day] were studied on two 36-h-long visits. In random order, subjects received closed-loop therapy with either standard or reduced insulin boluses administered with main meals (50-80 g carbohydrates) but not with snacks (15-30 g carbohydrates). Stable-label tracer dilution methodology measured total glucose appearance (Ra_total) and glucose disposal (Rd). RESULTS: The median (interquartile range) time spent in target (3.9-10 mmol/l) was similar between the two interventions [74 (66, 84)% vs 80 (65, 96)%; p = 0.87] as was time spent above 10 mmol/l [21.8 (16.3, 33.5)% vs 18.0 (4.1, 34.2)%; p = 0.87] and below 3.9 mmol/l [0 (0, 1.5)% vs 0 (0, 1.8)%; p = 0.88]. Mean plasma glucose was identical during the two interventions [8.4 (0.9) mmol/l; p = 0.98]. Hypoglycaemia occurred once 1.5 h post-meal during closed-loop therapy with standard bolus. Overall insulin delivery was lower with reduced prandial boluses [61.9 (55.2, 75.0) vs 72.5 (63.6, 80.3) IU; p = 0.01] and resulted in lower mean plasma insulin concentration [186 (171, 260) vs 252 (198, 336) pmol/l; p = 0.002]. Lower plasma insulin was also documented overnight [160 (136, 192) vs 191 (133, 252) pmol/l; p = 0.01, pooled nights]. Ra_total was similar [26.3 (21.9, 28.0) vs 25.4 (21.0, 29.2) µmol/kg/min; p = 0.19] during the two interventions as was Rd [25.8 (21.0, 26.9) vs 25.2 (21.2, 28.8) µmol/kg/min; p = 0.46]. CONCLUSIONS: A 25% reduction in prandial boluses during closed-loop therapy maintains similar glucose control in adolescents with T1D whilst lowering overall plasma insulin levels. It remains unclear whether closed-loop therapy with a 25% reduction in prandial boluses would prevent postprandial hypoglycaemia.

Effect of subcutaneous insulin detemir on glucose flux and lipolysis during hyperglycaemia in people with type 1 diabetes.

AIMS: To investigate, using a novel non-steady-state protocol, the differential effects of subcutaneous (s.c.) detemir and NPH insulin on glucose flux and lipid metabolism after insulin withdrawal. METHODS: After a period of insulin withdrawal resulting in whole-blood glucose concentration of 7 mmol/l, 11 participants (five men, mean age 41.0 years, mean body mass index 25 kg/m(2)) with type 1 diabetes (mean glycated haemoglobin concentration 57 mmol/mol, mean diabetes duration 14 years) received 0.5 units per kg body weight s.c. insulin detemir or NPH insulin in random order. Stable isotopes of glucose and glycerol were infused intravenously throughout the study protocol. RESULTS: Glucose concentration decreased after insulin treatment as a result of suppression of endogenous glucose production, which occurred to a similar extent with both detemir and NPH insulin. The rate of glucose disappearance (Rd) was not increased significantly with either type of insulin. When the effect of detemir and NPH insulin on glucose flux at glucose concentrations between 9 and 6 mmol/l was examined, glucose rate of appearance (Ra) was similar with the two insulins; however, glucose Rd was greater with NPH insulin than with detemir at glucose concentrations of 8.0, 8.5, 7.0 and 6.0 mmol/l (p < 0.05) The percentage change in glycerol Ra, a measure of lipolysis, was greater in the NPH group than in the detemir group (p = 0.04). CONCLUSIONS: The results of the study are consistent with the hypothesis that detemir has a lesser effect on the periphery, as evidenced by a lesser effect on peripheral glucose uptake at specific glucose concentrations.

Glucose turnover after replacement of usual therapy by insulin in insulin-naive type 2 diabetes subjects.

CONTEXT: Discontinuation of anti-hyperglycemic oral agents and initiation of insulin is recommended in certain clinical situations for inpatients with type 2 diabetes (T2D). The effects on glucose turnover when these agents are acutely withdrawn are poorly understood and may be of importance when insulin therapy is initiated. OBJECTIVE: Our objective was to investigate alterations in glucose turnover after acute withdrawal of noninsulin therapy. DESIGN AND SETTING: This was a randomized crossover study at a clinical research facility. PARTICIPANTS: Participants included 12 insulin-naive subjects with T2D. METHODS: Subjects attended two 24-hour visits. Standard therapy was discontinued and replaced by closed-loop insulin delivery during the intervention visit. Usual anti-hyperglycemic therapy was continued during the control visit. Systemic glucose appearance (Ra) and glucose disposal (Rd) were measured using a tracer dilution technique with iv [6,6-(2)H2]glucose. RESULTS: Plasma glucose profiles during both visits were comparable (P = .48). Glucose Ra increased during the day (21.4 [19.5, 23.5] vs 18.6 [17.0, 21.6) µmol/kg/min, P = .019) and decreased overnight (9.7 [8.5, 11.4] vs 11.6 [10.3, 12.9] µmol/kg/min, P = .004) when the usual therapy was discontinued and replaced with insulin. Increased daytime glucose Rd (21.2 [19.4, 23.9] vs 18.8 [18.3, 21.7] µmol/kg/min, P = .002) and decreased overnight Rd (10.4 [9.1, 12.0] vs 11.8 [10.7, 13.7] µmol/kg/min, P = .005) were observed when the usual therapy was discontinued, whereas daytime peripheral insulin sensitivity was reduced (47.8 [24.8, 66.1] vs 62.5 [34.8, 75.8] nmol/kg/min per pmol/L, P = .034). CONCLUSION: In T2D, acute discontinuation of anti-hyperglycemic therapy and replacement with insulin increases postprandial Ra and reduces peripheral insulin sensitivity. Insulin dose initiation may need to compensate for these alterations.

Efficacy of increased resistant starch consumption in human type 2 diabetes.

Resistant starch (RS) has been shown to beneficially affect insulin sensitivity in healthy individuals and those with metabolic syndrome, but its effects on human type 2 diabetes (T2DM) are unknown. This study aimed to determine the effects of increased RS consumption on insulin sensitivity and glucose control and changes in postprandial metabolites and body fat in T2DM. Seventeen individuals with well-controlled T2DM (HbA1c 46.6±2 mmol/mol) consumed, in a random order, either 40 g of type 2 RS (HAM-RS2) or a placebo, daily for 12 weeks with a 12-week washout period in between. AT THE END OF EACH INTERVENTION PERIOD, PARTICIPANTS ATTENDED FOR THREE METABOLIC INVESTIGATIONS: a two-step euglycemic-hyperinsulinemic clamp combined with an infusion of [6,6-(2)H2] glucose, a meal tolerance test (MTT) with arterio-venous sampling across the forearm, and whole-body imaging. HAM-RS2 resulted in significantly lower postprandial glucose concentrations (P=0.045) and a trend for greater glucose uptake across the forearm muscle (P=0.077); however, there was no effect of HAM-RS2 on hepatic or peripheral insulin sensitivity, or on HbA1c. Fasting non-esterified fatty acid (NEFA) concentrations were significantly lower (P=0.004) and NEFA suppression was greater during the clamp with HAM-RS2 (P=0.001). Fasting triglyceride (TG) concentrations and soleus intramuscular TG concentrations were significantly higher following the consumption of HAM-RS2 (P=0.039 and P=0.027 respectively). Although fasting GLP1 concentrations were significantly lower following HAM-RS2 consumption (P=0.049), postprandial GLP1 excursions during the MTT were significantly greater (P=0.009). HAM-RS2 did not improve tissue insulin sensitivity in well-controlled T2DM, but demonstrated beneficial effects on meal handling, possibly due to higher postprandial GLP1.

Short-term administration of pegvisomant improves hepatic insulin sensitivity and reduces soleus muscle intramyocellular lipid content in young adults with type 1 diabetes.

CONTEXT: Data on the metabolic effects of GH derived from studies using GH suppression by pharmacological agents may not reflect selective actions. OBJECTIVE: The purpose of this study was to evaluate the effects of GH antagonism on glucose and lipid metabolism using pegvisomant, a selective GH receptor antagonist in patients with type 1 diabetes (T1D). DESIGN AND PARTICIPANTS: In a randomized, placebo-controlled, crossover study, 10 young adults with T1D were evaluated at baseline and after 4 weeks of treatment with either 10 mg of pegvisomant or placebo. The assessments included an overnight euglycemic steady state followed by a hyperinsulinemic euglycemic clamp and used glucose and glycerol cold stable isotopes. OUTCOME MEASURES: Hepatic and peripheral insulin sensitivity (IS), lipid turnover, and intramyocellular lipid (IMCL) were measured. RESULTS: Compared with placebo, pegvisomant treatment resulted in lower IGF-I levels (P < .001). During the overnight steady state, insulin requirements for euglycemia (P = .019), insulin levels (P = .008), and glucose production rates (Ra) (P = .033) were reduced. During the clamp study, glucose infusion rates (P = .031) increased and glucose Ra (P = .015) decreased whereas glucose disposal rates were unchanged. Free fatty acid levels were similar during the steady state but were lower during the clamp (P = .040) after pegvisomant. Soleus muscle IMCL decreased after treatment (P = .024); however, no change in tibialis anterior muscle was observed. CONCLUSIONS: The study demonstrates that GH antagonism in T1D results in improved hepatic insulin sensitivity. Lack of consistent changes in free fatty acid levels may suggest a direct effect of GH on IS. Unchanged peripheral IS despite reductions in IMCL indicate that GH-induced alterations in IMCL may not be causally linked to glucose metabolism.

Absorption patterns of meals containing complex carbohydrates in type 1 diabetes.

AIMS/HYPOTHESIS: Successful postprandial glycaemia management requires understanding of absorption patterns after meals containing variable complex carbohydrates. We studied eight young participants with type 1 diabetes to investigate a large low-glycaemic-load (LG) meal and another eight participants to investigate a high-glycaemic-load (HG) meal matched for carbohydrates (121 g). METHODS: On Visit 1, participants consumed an evening meal. On follow-up Visit 2, a variable-target glucose clamp was performed to reproduce glucose and insulin levels from Visit 1. Adopting stable-label tracer dilution methodology, we measured endogenous glucose production on Visit 2 and subtracted it from total glucose appearance measured on Visit 1 to obtain meal-attributable glucose appearance. RESULTS: After the LG meal, 25%, 50% and 75% of cumulative glucose appearance was at 88 ± 21, 175 ± 39 and 270 ± 54 min (mean ± SD), whereas glucose from the HG meal appeared significantly faster at 56 ± 12, 100 ± 25 and 153 ± 39 min (p < 0.001 to 0.003), and resulted in a 50% higher peak appearance (p < 0.001). Higher apparent bioavailability by 15% (p = 0.037) was observed after the LG meal. We documented a 20 min deceleration of dietary mixed carbohydrates compared with dietary glucose for the HG meal and a twofold deceleration for the LG meal. CONCLUSIONS/INTERPRETATION: Absorption patterns may be influenced by glycaemic load and/or meal composition, affecting optimum prandial insulin dosing in type 1 diabetes.

Validity of triple- and dual-tracer techniques to estimate glucose appearance.

The triple-tracer (TT) dilution technique has been proposed to be the gold standard method to measure postprandial glucose appearance. However, validation against an independent standard has been missing. We addressed this issue and also validated the simpler dual-tracer (DT) technique. Sixteen young subjects with type 1 diabetes (age 19.5 ± 3.8 yr, BMI 23.4 ± 1.5 kg/m(2), HbA(1c) 8.7 ± 1.7%, diabetes duration 9.0 ± 6.9 yr, total daily insulin 0.9 ± 0.2 U·kg(-1)·day(-1), mean ± SD) received a variable intravenous 20% dextrose infusion enriched with [U-(13)C]glucose over 8 h to achieve postprandial-resembling glucose excursions while intravenous insulin was administered to achieve postprandial-resembling levels of plasma insulin. Primed [6,6-(2)H(2)]glucose was infused in a manner that mimicked the expected endogenous glucose production and [U-(13)C; 1,2,3,4,5,6,6-(2)H(7)]glucose was infused in a manner that mimicked the expected glucose appearance from a standard meal. Plasma glucose enrichment was measured by gas chromatography-mass spectrometry. The intravenous dextrose infusion served as an independent standard and was reconstructed using the TT and DT techniques with the two-compartment Radziuk/Mari model and an advanced stochastic computational method. The difference between the infused and reconstructed dextrose profile was similar for the two methods (root mean square error 6.6 ± 1.9 vs. 8.0 ± 3.5 µmol·kg(-1)·min(-1), TT vs. DT, P = NS, paired t-test). The TT technique was more accurate in recovering the overall dextrose infusion (100 ± 9 and 92 ± 12%; P = 0.02). The root mean square error associated with the mean dextrose infusion profile was 2.5 and 3.3 µmol·kg(-1)·min(-1) for the TT and DT techniques, respectively. We conclude that the TT and DT techniques combined with the advanced computational method can measure accurately exogenous glucose appearance. The TT technique tends to outperform slightly the DT technique, but the latter benefits from reduced experimental and computational complexity.

Pathophysiology of postprandial hyperglycaemia in women with type 1 diabetes during pregnancy.

AIMS/HYPOTHESIS: Although maternal hyperglycaemia is associated with increased risk of adverse pregnancy outcome, the mechanisms of postprandial hyperglycaemia during pregnancy are poorly understood. We aimed to describe glucose turnover in pregnant women with type 1 diabetes, according to stage of gestation (early vs late gestation). METHODS: The rates of systemic glucose appearance (R(a)) and glucose disposal (R(d)) were measured in ten pregnant women with type 1 diabetes during early (12-16 weeks) and late (28-32 weeks) gestation. Women ate standardised meals--a starch-rich 80 g carbohydrate dinner and a sugar-rich 60 g carbohydrate breakfast--and fasted between meals and overnight. Stable-label isotope tracers ([6,6-(2)H(2)]glucose and [U-(13)C]glucose) were used to determine R(a), R(d) and glucose bioavailability. Closed-loop insulin delivery maintained stable glycaemic conditions. RESULTS: There were no changes in fasting R(a) (10 ± 2 vs 11 ± 2 µmol kg(-1) min(-1); p = 0.32) or fasting R(d) (11 ± 2 vs 11 ± 1 µmol kg(-1) min(-1); p = 0.77) in early vs late gestation. There was increased hepatic insulin resistance (381 ± 237 vs 540 ± 242 µmol kg(-1) min(-1) × pmol/l; p = 0.04) and decreased peripheral insulin sensitivity (0.09 ± 0.04 vs 0.05 ± 0.02 µmol kg(-1) min(-1) per pmol/l dinner, 0.11 ± 0.05 vs 0.07 ± 0.03 µmol kg(-1) min(-1) per pmol/l breakfast; p = 0.002) in late gestation. It also took longer for insulin levels to reach maximal concentrations (49 [37-55] vs 71 [52-108] min; p = 0.004) with significantly delayed glucose disposal (108 [87-125] vs 135 [110-158] min; p = 0.005) in late gestation. CONCLUSIONS/INTERPRETATION: Postprandial glucose control is impaired by significantly slower glucose disposal in late gestation. Early prandial insulin dosing may help to accelerate glucose disposal and potentially ameliorate postprandial hyperglycaemia in late pregnancy. TRIAL REGISTRATION: ISRCTN 62568875 FUNDING: Diabetes UK Project Grant BDA 07/003551. H.R. Murphy is funded by a National Institute for Health Research (NIHR) research fellowship (PDF/08/01/036). Supported also by the Juvenile Diabetes Research Foundation (JDRF), Abbott Diabetes Care (Freestyle Navigator CGM and sensors free of charge), Medical Research Council Centre for Obesity and Related Metabolic Diseases and NIHR Cambridge Biomedical Research Centre.

Metabolic effects of intensive insulin therapy in critically ill patients.

Our aim was to investigate the effects of glycemic control and insulin concentration on lipolysis, glucose, and protein metabolism in critically ill medical patients. For our methods, the patients were studied twice. In study 1, blood glucose (BG) concentrations were maintained between 7 and 9 mmol/l with intravenous insulin. After study 1, patients entered one of four protocols for 48 h until study 2: low-insulin high-glucose (LIHG; variable insulin, BG of 7-9 mmol/l), low-insulin low-glucose (LILG; variable insulin of BG 4-6 mmol/l), high-insulin high-glucose [HIHG; insulin (2.0 mU . kg(-1).min(-1) plus insulin requirement from study 1), BG of 7-9 mmol/l], or high-insulin low-glucose [HILG; insulin (2.0 mU.kg(-1).min(-1) plus insulin requirement from study 1), BG of 4-6 mmol/l]. Age-matched healthy control subjects received two-step euglycemic hyperinsulinemic clamps achieving insulin levels similar to the LI and HI groups. In our results, whole body proteolysis was higher in patients in study 1 (P < 0.006) compared with control subjects at comparable insulin concentrations and was reduced with LI (P < 0.01) and HI (P = 0.001) in control subjects but not in patients. Endogenous glucose production rate (R(a)), glucose disposal, and lipolysis were not different in all patients in study 1 compared with control subjects at comparable insulin concentrations. Glucose R(a) and lipolysis did not change in any of the study 2 patient groups. HI increased glucose disposal in the patients (HIHG, P = 0.001; HILG, P = 0.07 vs. study 1), but this was less than in controls receiving HI (P < 0.03). In conclusion, low-dose intravenous insulin administered to maintain BG between 7-9 mmol/l is sufficient to limit lipolysis and endogenous glucose R(a) and increase glucose R(d). Neither hyperinsulinemia nor normoglycemia had any protein-sparing effect.

Effects of rosiglitazone and pioglitazone on lipoprotein metabolism in patients with Type 2 diabetes and normal lipids.

AIMS: Previous studies have suggested that plasma lipids are affected differently by the peroxisome proliferators-activated receptor (PPAR)-gamma agonists pioglitazone and rosiglitazone. The aim of this study was to perform a quantitative lipoprotein turnover study to determine the effects of PPAR-gamma agonists on lipoprotein metabolism. METHODS: Twenty-four subjects with Type 2 diabetes treated with diet and/or metformin were randomized in a double-blind study to receive 30 mg pioglitazone, 8 mg rosiglitazone or placebo once daily for 3 months. Before and after treatment, absolute secretion rate (ASR) and fractional catabolic rate (FCR) of very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL) and low-density lipoprotein (LDL) apolipoprotein B100 were measured with a 10-h infusion of 1-13C leucine. RESULTS: There was a significant decrease in glycated haemoglobin (HbA(1c)) and non-esterified fatty acids with pioglitazone (P = 0.01; P = 0.02) and rosiglitazone (P = 0.04; P = 0.003), respectively, but no change in plasma triglyceride or high-density lipoprotein (HDL) cholesterol. Following rosiglitazone, there was a significant reduction in VLDL apolipoprotein B100 (apoB) ASR (P = 0.01) compared with baseline, a decrease in VLDL triglyceride/apoB (P = 0.01), an increase in LDL2 cholesterol (P = 0.02) and a decrease in LDL3 cholesterol (P = 0.02). There was a decrease in VLDL triglyceride/apoB (P = 0.04) in the pioglitazone group. There was no significant difference in change in VLDL ASR or FCR among the three groups. CONCLUSIONS: In patients with Type 2 diabetes and normal lipids, treatment with rosiglitazone or pioglitazone had no significant effect on lipoprotein metabolism compared with placebo.

Differential effects of insulin detemir and neutral protamine Hagedorn (NPH) insulin on hepatic glucose production and peripheral glucose uptake during hypoglycaemia in type 1 diabetes.

AIMS/HYPOTHESIS: We compared the symptoms of hypoglycaemia induced by insulin detemir (NN304) (B29Lys(epsilon-tetradecanoyl),desB30 human insulin) and equally effective doses of neutral protamine Hagedorn (NPH) insulin in relation to possible differential effects on hepatic glucose production and peripheral glucose uptake. METHODS: After overnight intravenous infusion of soluble human insulin 18 participants with type 1 diabetes received subcutaneous injections of NPH insulin or insulin detemir (0.5 U/kg body weight) on separate occasions in random order. During the ensuing gradual development of hypoglycaemia cognitive function and levels of counter-regulatory hormones were measured and rates of endogenous glucose production and peripheral glucose uptake continuously evaluated using a primed constant infusion of [6,6-(2)H(2)]glucose. The study was terminated when plasma glucose concentration had fallen to 2.4 mmol/l or had reached a minimum at a higher concentration. RESULTS: During the development of hypoglycaemia no difference between the two insulin preparations was observed in symptoms or hormonal responses. Significant differences were seen in rates of glucose flux. At and below plasma glucose concentrations of 3.5 mmol/l suppression of endogenous glucose production was greater with insulin detemir than with NPH insulin, whereas stimulation of peripheral glucose uptake was greater with NPH insulin than with insulin detemir. CONCLUSIONS/INTERPRETATION: In participants with type 1 diabetes subcutaneously injected insulin detemir exhibits relative hepatoselectivity compared with NPH insulin, but symptoms of hypoglycaemia and hormonal counter-regulation are similar. TRIAL REGISTRATION: ClinicalTrials.gov NCT00760448.

Pegvisomant improves insulin sensitivity and reduces overnight free fatty acid concentrations in patients with acromegaly.

INTRODUCTION: Acromegaly is complicated by an increased incidence of diabetes mellitus caused by impaired insulin sensitivity and reduced beta-cell function. Pegvisomant blocks activity at GH receptors, normalizing IGF-I in over 90% of patients and improving insulin sensitivity. The mechanisms for this increase in insulin sensitivity are not fully determined. We used stable isotope techniques to investigate the effects of pegvisomant on glucose and lipid metabolism in acromegaly. METHODS: Five patients (age, 43 yr +/- sd) with active acromegaly were studied on two occasions: before pegvisomant and after 4 wk of pegvisomant (20 mg daily sc). (2)H(5)-glycerol was infused overnight to measure overnight and early morning (basal) glycerol production rate (Ra). The next morning (2)H(2)-glucose was infused for 2 h before and throughout a hyperinsulinemic euglycemic (1.5 mU/kg x min insulin) clamp to measure basal glucose Ra and insulin-stimulated peripheral glucose disposal (Rd). RESULTS: Mean IGF-I was significantly reduced after pegvisomant treatment (mean, 539 +/- 176 vs. 198 +/- 168 microg/ml; P = 0.001). The insulin sensitivity of endogenous glucose production was significantly increased after pegvisomant [mean glucose Ra *insulin, 118.5 +/- 28 vs. 69.2 +/- 22 micromol/kg x min *(mU/liter); P = 0.04]. No differences in glucose Rd were seen after pegvisomant. All patients showed a reduction in glycerol Ra adjusted for insulin [mean, 18.12 +/- 1.75 vs. 14.4 +/- 4.75 micromol/kg x min *(mU/liter); P = 0.08] and overnight FFA concentrations (mean area under the curve, 278 +/- 84 vs. 203 +/- 71; P < 0.05) after pegvisomant. CONCLUSION: Short-term administration of pegvisomant leads to a reduction in overnight endogenous glucose production, and this may be related to reduced levels of FFA.

Severe intrauterine growth retardation and atypical diabetes associated with a translocation breakpoint disrupting regulation of the insulin-like growth factor 2 gene.

CONTEXT: IGF-II is an imprinted gene (predominantly transcribed from the paternally inherited allele), which has an important role in fetal growth in mice. IGF2 gene expression is regulated by a complex system of enhancers and promoters that determine tissue-specific and development-specific transcription. In mice, enhancers of the IGF2 gene are located up to 260 kb telomeric to the gene. The role of IGF-II in humans is unclear. OBJECTIVE: A woman of short adult stature (1.46 m, -3 sd score) born with severe intrauterine growth retardation (1.25 kg at term, -5.4 SD score) and atypical diabetes diagnosed at the age of 23 yr had a balanced chromosomal translocation t(1;11) (p36.22; p15.5). We hypothesized that her phenotype resulted from disruption of her paternally derived IGF2 gene because her daughter who inherited the identical translocation had normal birth weight. DESIGN: Both chromosomal break points were identified using fluorescent in situ hybridization. Sequence, methylation, and expression of the IGF2 gene was examined. Hyperinsulinemic, euglycemic clamp with glucose tracers and magnetic resonance imaging of the thorax, abdomen, and pelvis were performed. RESULTS: The 11p15.5 break point mapped 184 kb telomeric of the IGF2 gene. Microsatellite markers confirmed paternal origin of this chromosome. IGF2 gene sequence and methylation was normal. IGF2 gene expression was reduced in lymphoblasts. Clamp studies showed marked hepatic and total insulin resistance. Massive excess sc fat was seen on magnetic resonance imaging despite slim body mass index (21.1 kg/m2). CONCLUSIONS: A break point 184 kb upstream of the paternally derived IGF2 gene, separating it from some telomeric enhancers, resulted in reduced expression in some mesoderm-derived adult tissues causing intrauterine growth retardation, short stature, lactation failure, and insulin resistance with altered fat distribution.

Measurement of endogenous and exogenous triacylglycerol kinetics in the fed and fasted states.

Emerging evidence has shown that an abnormal postprandial accumulation of dietary fat is atherogenic. However, there is a lack of data describing the mechanisms for accumulation of triacylglycerol (TAG) in the postprandial period. There is therefore a need to establish a specific measure of the kinetics of endogenous and exogenous TAG in the postprandial period.