Does prior acute exercise affect postexercise substrate oxidation in response to a high carbohydrate meal?

<p>Abstract</p> <p>Background</p> <p>Consumption of a mixed meal increases postprandial carbohydrate utilization and decreases fat oxidation. On the other hand, acute endurance exercise increases fat oxidation and decreases carbohydrate utilization during the post-exercise recovery period. It is possible that the resulting post-exercise increase in circulating nonesterified fatty acids could attenuate the ability of ingested carbohydrate to inhibit lipid oxidation. The purpose of this study was to determine whether prior exercise attenuates the usual meal-induced decline in lipid oxidation.</p> <p>Methods</p> <p>Six healthy, physically active young subjects (x age = 26.3 years, 4 males, 2 females) completed three treatments in random order after a ~10 h fast: (a) Exercise/Carbohydrate (Ex/CHO) – subjects completed a bout of exercise at 70% VO_2peak(targeted net energy cost of 400 kcals), followed by consumption of a carbohydrate-rich meal; (b) Exercise/Placebo (Ex/Placebo) – subjects completed an identical bout of exercise followed by consumption of a placebo; and (c) No Exercise/Carbohydrate (NoEx/CHO) – subjects sat quietly rather than exercising and then consumed the carbohydrate-rich meal. Blood samples were obtained before and during the postprandial period to determine plasma glucose, insulin, and non-esterified fatty acids (NEFA). Respiratory gas exchange measures were used to estimate rates of fat and carbohydrate oxidation.</p> <p>Results</p> <p>Plasma NEFA were approximately two-fold higher immediately following the two exercise conditions compared to the no-exercise condition, while meal consumption significantly increased insulin and glucose in both Ex/CHO and NoEx/CHO. NEFA concentrations fell rapidly during the 2-h postprandial period, but remained higher compared to the NoEx/CHO treatment. Carbohydrate oxidation increased rapidly and fat oxidation decreased in response to the meal, with no differences in the rates of carbohydrate and fat oxidation during recovery between the Ex/CHO and NoEx/CHO conditions.</p> <p>Conclusion</p> <p>The plasma NEFA concentration is increased during the post exercise period, which is associated with elevated fat oxidation when no meal is consumed. However, when a mixed meal is consumed immediately following exercise, the initially elevated plasma NEFA concentration decreases rapidly, and postexercise fat oxidation during this 2-h postexercise, postprandial period is no higher than that of the 2-h postprandial period without prior exercise.</p

Closed-loop insulin delivery for treatment of type 1 diabetes

Type 1 diabetes is one of the most common endocrine problems in childhood and adolescence, and remains a serious chronic disorder with increased morbidity and mortality, and reduced quality of life. Technological innovations positively affect the management of type 1 diabetes. Closed-loop insulin delivery (artificial pancreas) is a recent medical innovation, aiming to reduce the risk of hypoglycemia while achieving tight control of glucose. Characterized by real-time glucose-responsive insulin administration, closed-loop systems combine glucose-sensing and insulin-delivery components. In the most viable and researched configuration, a disposable sensor measures interstitial glucose levels, which are fed into a control algorithm controlling delivery of a rapid-acting insulin analog into the subcutaneous tissue by an insulin pump. Research progress builds on an increasing use of insulin pumps and availability of glucose monitors. We review the current status of insulin delivery, focusing on clinical evaluations of closed-loop systems. Future goals are outlined, and benefits and limitations of closed-loop therapy contrasted. The clinical utility of these systems is constrained by inaccuracies in glucose sensing, inter- and intra-patient variability, and delays due to absorption of insulin from the subcutaneous tissue, all of which are being gradually addressed.Supported by the Juvenile Diabetes Research Foundation (#22-2006-1113, #22-2007-1801, #22-2009-801), Diabetes UK (BDA07/0003549, BDA07/0003551), European Commission Framework Programme 7 (247138), NIDDK (DK085621), and NIHR Cambridge Biomedical Research Centre

Lack of benefit from the intermittent administration of insulin in treatment using subcutaneous perfusion pump in type 1 diabetes

Our study is based on two constatations: 1) Hyperinsulinaemia, a possible atherogenic factor, is frequent under continuous subcutaneous insulin infusion. 2) Pulsatile intravenous insulin delivery improve the insulin's hypoglycaemic activity. To test if equivalent metabolic control can be obtained with a reduced intermittent subcutaneous infused insulin dose, we compared nocturnal metabolic control of 8 c-peptide negative type 1 diabetic patients under three experimental conditions: Continuous usual dose test (1.0 +/- 0.1 u/h); Intermittent half dose test (1.0 +/- 0.1 u/h, 30 min/h); Continuous half dose test (0.5 +/- 0.05 u/h) Five parameters were monitored: blood glucose, plasma free insulin and beta-hydroxy-butyrate, free fatty acid and glycerol plasma level. No significant differences were found between intermittent and continuous half-dose tests. We conclude that, in our experimental conditions, intermittent subcutaneous insulin infusion does not reduce the metabolic degradation induced by insulin dose reduction

A 6-hour nocturnal interruption of a continuous subcutaneous insulin infusion: 1. Metabolic and hormonal consequences and scheme for a prompt return to adequate control.

Interruption of a continuous subcutaneous insulin infusion, most often due to technical problems occurring during the night, is a not uncommon event whose metabolic consequences have received relatively little attention until now. We have therefore investigated the changes in blood glucose, plasma non-esterified fatty acids, 3-hydroxybutyrate, glucagon and free insulin in eight C-peptide negative Type 1 diabetic patients whose pumps were deliberately stopped between 23.00 h and 05.00 h. A control test with the pump functioning normally was carried out in each patient and the studies were randomized. Considering the values at 23.00 h as reference, interruption of the insulin infusion resulted in (1) a rapid decrease in plasma free insulin significant after 1 h and reaching a nadir of 6 +/- 2 mU/l after 6 h; (2) a rise in blood glucose which was significant at hour 3 and reached 17.4 +/- 1.9 mmol/l at hour 6; (3) a moderate increase in plasma nonesterified fatty acids which remained in the range of 700-800 mumol/l; (4) an early and linear rise in plasma 3-hydroxybutyrate, significant after 1 h and averaging 1290 +/- 140 mumol/l after 6 h; (5) a late increase (hour 5) in plasma glucagon. The second aim of our study was to provide for the patient a precise scheme of insulin supplements administered via the pump and based on blood glucose monitoring (Dextrostix - Glucometer) and semi-quantitative evaluation of ketonuria (Acetest). Resetting the pump at its basal rate at 05.00 h and giving insulin supplements (2-8 U) at 06.45 h (with the usual breakfast dose) and again at 10.00 h have proved efficacious in restoring satisfactory metabolic control by noon the day after starting the experiment. These results form practical recommendations to patients undergoing this type of accident

Metabolic alterations after a two-hour nocturnal interruption of a continuous subcutaneous insulin infusion.

In order to evaluate the metabolic consequences of a 2-h nocturnal interruption of continuous subcutaneous insulin infusion (CSII), seven insulin-dependent diabetic patients without residual insulin secretion were investigated. The changes in blood glucose, plasma free insulin, glucagon, free fatty acids, and 3-hydroxybutyrate (3 OH-B) concentrations have been compared during two randomized tests carried out either during the normal functioning of a Mill-Hill pump from 10 p.m. to 8 a.m. (1.00 +/- 0.06 U insulin/h, keeping adequate metabolic control) or during the same conditions but with a deliberate arrest of the pump between 11 p.m. and 1 a.m. Considering the value recorded at 11 p.m. as reference, interruption of the insulin infusion resulted in: (1) a rapid (already significant after 1 h) and sustained (maximal fall: --12.5 +/- 2.5 mU/L at 3 a.m.) decrease in plasma free insulin; (2) a delayed (significant after 4 h) and linear rise in blood glucose (maximal increase: + 4.0 +/- 1.3 mmol/L at 5 a.m.); (3) an early (significant at midnight) and prolonged rise in plasma free fatty acids (+ 387 +/- 148 mumol/L at 3 a.m.); (4) a delayed (significant after 3 h) and sustained increase in plasma 3 OH-B (+ 347 +/- 88 mumol/L at 3 a.m.); and (5) no significant changes in plasma glucagon. Thus, a 2-h interruption of CSII in resting nocturnal conditions is sufficient to induce significant, delayed, and sustained metabolic alterations in C-peptide-negative patients despite good baseline blood glucose control. Resetting the pump at its basal rate is insufficient to quickly restore adequate circulating insulin levels and effectively counteract the metabolic disturbances. The efficacy of a bolus insulin injection in these conditions should be evaluated

Fluoxetine therapy in obese diabetic and glucose intolerant patients.

A double-blind placebo-controlled trial was conducted, involving 97 obese diabetic and glucose intolerant patients receiving either 60 mg fluoxetine daily (47 patients) or a placebo (50 patients); a similar calorie-restricted diet was prescribed to all patients. Weight loss was significantly higher in the fluoxetine-treated patients, whose diabetic status improved. Drop-out rate was not significantly different for both groups of patients