Acute cortisol excess results in unimpaired insulin action on lipolysis and branched chain amino acids, but not on glucose kinetics and C-peptide concentrations in man

Glucocorticoids, metabolism and brain activity

The review integrates different experimental approaches including biochemistry, c-Fos expression, microdialysis (glutamate, GABA, noradrenaline and serotonin), electrophysiology and fMRI to better understand the effect of elevated level of glucocorticoids on the brain activity and metabolism. The available data indicate that glucocorticoids alter the dynamics of neuronal activity leading to context-specific changes including both excitation and inhibition and these effects are expected to support the task-related responses. Glucocorticoids also lead to diversification of available sources of energy due to elevated levels of glucose, lactate, pyruvate, mannose and hydroxybutyrate (ketone bodies), which can be used to fuel brain, and facilitate storage and utilization of brain carbohydrate reserves formed by glycogen. However, the mismatch between carbohydrate supply and utilization that is most likely to occur in situations not requiring energy-consuming activities lead to metabolic stress due to elevated brain levels of glucose. Excessive doses of glucocorticoids also impair the production of energy (ATP) and mitochondrial oxidation. Therefore, glucocorticoids have both adaptive and maladaptive effects consistently with the concept of allostatic load and overload.

Exogenous GLP-1 stimulates TCA cycle and suppresses gluconeogenesis and ketogenesis in late-fasted northern elephant seals pups

The postweaning fast of northern elephant seal pups is characterized by a lipid-dependent metabolism and associated with a decrease in plasma glucagon-like peptide-1 (GLP-1), insulin, and glucose and increased gluconeogenesis (GNG) and ketogenesis. We have also demonstrated that exogenous GLP-1 infusion increased plasma insulin despite simultaneous increases in cortisol and glucagon, which collectively present contradictory regulatory stimuli of GNG, ketogenesis, and glycolysis. To assess the effects of GLP-1 on metabolism using primary carbon metabolite profiles in late-fasted seal pups, we dose-dependently infused late-fasted seals with low (LDG; 10 pM/kg; n = 3) or high (HDG; 100 pM/kg; n = 4) GLP-1 immediately following a glucose bolus (0.5 g/kg), using glucose without GLP-1 as control (n = 5). Infusions were performed in similarly aged animals 6-8 wk into their postweaning fast. The plasma metabolome was measured from samples collected at five time points just prior to and during the infusions, and network maps constructed to robustly evaluate the effects of GLP-1 on primary carbon metabolism. HDG increased key tricarboxylic acid (TCA) cycle metabolites, and decreased phosphoenolpyruvate and acetoacetate (P < 0.05) suggesting that elevated levels of GLP-1 promote glycolysis and suppress GNG and ketogenesis, which collectively increase glucose clearance. These GLP-1-mediated effects on cellular metabolism help to explain why plasma GLP-1 concentrations decrease naturally in fasting pups as an evolved mechanism to help conserve glucose during the late-fasting period.

A randomized cross-over study of the acute effects of running 5 km on glucose, insulin, metabolic rate, cortisol and Troponin T

Background

We aimed to study the impact by running 5 km, at maximal speed, on the normal variations of metabolic variables related to glucose, insulin, insulin sensitivity, cortisol, glucagon, Troponin T and metabolic rate.

Material and methods

Five women and 12 men 25.7±5.2 years of age with a body-mass-index of 22.5±2.3 kg/m² where recruited to run 5 km at individual maximal speed in the morning, and to a corresponding day of rest, followed by standardized breakfast and lunch meals. Blood sampling and measurement of indirect calorimetry were done before and after meals. The participants were randomized regarding the order of the two trial-days in this cross-over study.

Results

Insulin and cortisol levels were higher, and insulin sensitivity was lower, on the race-day compared with the day of rest (linear mixed model: p<0.0001 for all three analyses). However, glucose levels and metabolic rate did not differ between the two trial days (p = 0.29 and p = 0.53, respectively). When analyzing specific time-points we found that glucose increased from 5.01±0.37 mmol/l to 6.36 ± 1.3 mmol/l, p<0.0001, by running, while serum insulin concomitantly increased from 42±21 to 90±54 pmol/l, p<0.0001. In accordance, the QUICKI index of serum sensitivity, 1/(log₁₀insulin+log₁₀glucose), was lowered post-race, p<0.0001. Serum cortisol levels increased from 408±137 nmol/l to 644±171 nmol/l, p<0.0001, post-race while serum glucagon levels were unaffected. Troponin T was detectable in serum post-race in 12 out of the 17 participants and reached or surpassed the clinical reference level of 15 ng/l in three subjects. Post-race electrocardiograms displayed no pathologies.

Conclusions

Relatively short running-races can apparently induce a reduction in insulin sensitivity that is not fully compensated by concomitantly increased insulin secretion intended to ensure euglycemia. Since also Troponin T was detected in plasma in a majority of the participants, our data suggest that it is possible to induce considerable metabolic stress by running merely 5 km, when striving for maximal speed.

High Thoracic Epidural in Cardiac Anesthesia

High thoracic epidural analgesia (HTEA) offers a distinctive opportunity to enhance postoperative recovery for the thoracic surgery patient. In the modern hospital setting with day of admission surgery, the logistics of insertion of the epidural catheter has become increasingly difficult. The greatest limitation to its use might be the believed increased risk of epidural hematoma associated with anticoagulation during cardiopulmonary bypass. The aim of this review is to give an overview of complications and effect on outcomes with focus on cardiac performance and postoperative glycemic control and kidney function. Patients with epidurals may have improved postoperative pulmonary function and shorter ventilation time, while impact on length of stay in the intensive care unit and hospital is not as evident. HTEA is effective in pain management, attenuates perioperative stress and seems to improve postoperative blood glucose control. Whether HTEA improves recovery and facilitates fast-track is still to be confirmed. With regard to serious postoperative complications, there is evidence of reduction in supraventricular arrhythmias and lower frequency of postoperative acute kidney injury and dialysis. There are some indications of lower short term mortality and frequency of postoperative myocardial infarctions, but only as a combined outcome. The present short-term mortality of 1% to 2% should be compared with the most pessimistic frequency of epidural hematoma being 1 in 4600 patients.

Single-dose carbohydrate treatment in the immediate preoperative phase diminishes development of postoperative peripheral insulin resistance

BACKGROUND & AIMS

Preoperative oral carbohydrate (CHO) treatment is known to reduce postoperative insulin resistance, but the necessity of a preoperative evening dose is uncertain. We investigated the effect of single-dose CHO treatment two hours before surgery on postoperative insulin sensitivity.

METHODS

Thirty two pigs (∼ 30 kg) were randomized to 4 groups (n = 8) followed by D-[6,6-(2)H2] glucose infusion and hyperinsulinemic-euglycemic step clamping. Two groups received a morning drink of 25 g carbohydrate (CHO/surgery and CHO/control). Animals in the other two groups were fasted overnight (fasting/surgery and fasting/control). Counter-regulatory hormones, free fatty acids (FFA) and liver and muscle glycogen content were measured serially.

RESULTS

Glucose infusion rates needed to maintain euglycemia were higher after CHO/surgery than fasting/surgery during low (8.54 ± 0.82 vs. 6.15 ± 0.27 mg/kg/min, P < 0.05), medium (17.26 ± 1.08 vs. 14.02 ± 0.56 mg/kg/min, P < 0.02) and high insulin clamping (19.83 ± 0.95 vs. 17.16 ± 0.58 mg/kg/min, P < 0.05). The control groups exhibited identical insulin sensitivity. Compared to their respective controls, insulin-stimulated whole-body glucose disposal was significantly reduced after fasting/surgery (-41%, P < 0.001), but not after CHO/surgery (-16%, P = 0.180). CHO reduced FFA perioperatively (P < 0.05) and during the clamp procedures (P < 0.02), but did not affect hepatic insulin sensitivity, liver and muscle glycogen content or counter-regulatory hormone profiles. A strong negative correlation between peripheral insulin sensitivity and mean cortisol levels was seen in fasted (R = -0.692, P = 0.003), but not in CHO loaded pigs.

CONCLUSIONS

Single-dose preoperative CHO treatment is sufficient to reduce postoperative insulin resistance, possibly due to the antilipolytic effects and antagonist properties of preoperative hyperinsulinemia on the suppressant actions of cortisol on carbohydrate oxidation.

Exogenous glucocorticoids and a high-fat diet cause severe hyperglycemia and hyperinsulinemia and limit islet glucose responsiveness in young male Sprague-Dawley rats

Corticosterone (CORT) and other glucocorticoids cause peripheral insulin resistance and compensatory increases in β-cell mass. A prolonged high-fat diet (HFD) induces insulin resistance and impairs β-cell insulin secretion. This study examined islet adaptive capacity in rats treated with CORT and a HFD. Male Sprague-Dawley rats (age ∼6 weeks) were given exogenous CORT (400 mg/rat) or wax (placebo) implants and placed on a HFD (60% calories from fat) or standard diet (SD) for 2 weeks (N = 10 per group). CORT-HFD rats developed fasting hyperglycemia (>11 mM) and hyperinsulinemia (∼5-fold higher than controls) and were 15-fold more insulin resistant than placebo-SD rats by the end of ∼2 weeks (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR] levels, 15.08 ± 1.64 vs 1.0 ± 0.12, P < .05). Pancreatic β-cell function, as measured by HOMA-β, was lower in the CORT-HFD group as compared to the CORT-SD group (1.64 ± 0.22 vs 3.72 ± 0.64, P < .001) as well as acute insulin response (0.25 ± 0.22 vs 1.68 ± 0.41, P < .05). Moreover, β- and α-cell mass were 2.6- and 1.6-fold higher, respectively, in CORT-HFD animals compared to controls (both P < .05). CORT treatment increased p-protein kinase C-α content in SD but not HFD-fed rats, suggesting that a HFD may lower insulin secretory capacity via impaired glucose sensing. Isolated islets from CORT-HFD animals secreted more insulin in both low and high glucose conditions; however, total insulin content was relatively depleted after glucose challenge. Thus, CORT and HFD, synergistically not independently, act to promote severe insulin resistance, which overwhelms islet adaptive capacity, thereby resulting in overt hyperglycemia.

High thoracic epidural analgesia decreases stress hyperglycemia and insulin need in cardiac surgery patients

OBJECTIVE

Assuming that high thoracic epidural analgesia (HTEA) with the sympathetic block might decrease postoperative blood glucose (BG) level and reduce the need of insulin, the aim was to evaluate the effect of HTEA on the BG level and insulin requirement in patients undergoing cardiac surgery.

MATERIALS AND METHODS

Forty-two low-risk patients age 65-79 years scheduled for elective coronary artery bypass grafting with or without aortic valve replacement were randomised to receive HTEA as supplement for general anaesthesia. BG and lactate were measured before and after cardiopulmonary bypass and postoperatively at least every 3 h together with administration of insulin. Postoperative pain was evaluated 30 min, 2, 4 and 6 h after extubation, and before discharge from the intensive care unit.

RESULTS

Overall BG levels showed great variation over time (P < 0.001). No statistically significant difference was found in perioperative BG, but postoperative lower BG levels were found in HTEA patients (P = 0.042). The number of patients not receiving insulin in postoperative period was significantly higher in HTEA group (9 vs. 2, P = 0.032). No differences were seen in lactate levels. Patients in the HTEA group had significant lower pain scores (P < 0.001).

CONCLUSION

HTEA preserves glucose metabolism better and leads to a lesser degree of 'stress hyperglycaemia' in cardiac surgery patients.

Metabolism before, during and after anaesthesia in colic and healthy horses

BACKGROUND

Many colic horses are compromised due to the disease state and from hours of starvation and sometimes long trailer rides. This could influence their muscle energy reserves and affect the horses' ability to recover. The principal aim was to follow metabolic parameter before, during, and up to 7 days after anaesthesia in healthy horses and in horses undergoing abdominal surgery due to colic.

METHODS

20 healthy horses given anaesthesia alone and 20 colic horses subjected to emergency abdominal surgery were anaesthetised for a mean of 228 minutes and 183 minutes respectively. Blood for analysis of haematology, electrolytes, cortisol, creatine kinase (CK), free fatty acids (FFA), glycerol, glucose and lactate was sampled before, during, and up to 7 days after anaesthesia. Arterial and venous blood gases were obtained before, during and up to 8 hours after recovery. Gluteal muscle biopsy specimens for biochemical analysis of muscle metabolites were obtained at start and end of anaesthesia and 1 h and 1 day after recovery.

RESULTS

Plasma cortisol, FFA, glycerol, glucose, lactate and CK were elevated and serum phosphate and potassium were lower in colic horses before anaesthesia. Muscle adenosine triphosphate (ATP) content was low in several colic horses. Anaesthesia and surgery resulted in a decrease in plasma FFA and glycerol in colic horses whereas levels increased in healthy horses. During anaesthesia muscle and plasma lactate and plasma phosphate increased in both groups. In the colic horses plasma lactate increased further after recovery. Plasma FFA and glycerol increased 8 h after standing in the colic horses. In both groups, plasma concentrations of CK increased and serum phosphate decreased post-anaesthesia. On Day 7 most parameters were not different between groups. Colic horses lost on average 8% of their initial weight. Eleven colic horses completed the study.

CONCLUSION

Colic horses entered anaesthesia with altered metabolism and in a negative oxygen balance. Muscle oxygenation was insufficient during anaesthesia in both groups, although to a lesser extent in the healthy horses. The post-anaesthetic period was associated with increased lipolysis and weight loss in the colic horses, indicating a negative energy balance during the first week post-operatively.

Effects of hydrocortisone on substrates of energy metabolism in alpacas

OBJECTIVE

To evaluate effects of hydrocortisone administration, with and without concurrent administration of insulin, on intermediary metabolism in alpacas.

ANIMALS

8 adult castrated male alpacas.

PROCEDURE

On each of 2 consecutive days, food was withheld from alpacas for 8 hours. Alpacas then were administered 1 mg of hydrocortisone sodium succinate/kg, IV (time 0). On 1 of the days, randomly assigned alpacas were also administered regular insulin (0.2 U/kg, IV) 120 minutes after hydrocortisone administration. Blood samples were collected at 0, 120, 135, 150, 165, 180, 210, 240, 300, and 360 minutes. Plasma concentrations of glucose and lactate and serum concentrations of triglycerides, cholesterol, nonesterified fatty acids, and beta-hydroxybutyrate were determined. Data were compared between days. Additionally, serum insulin concentrations before and after hydrocortisone administration were determined for selected samples.

RESULTS

Hydrocortisone administration induced hyperglycemia, hyperinsulinemia, a reduction in concentrations of triglycerides and cholesterol, and a reduction in triglyceride-to-cholesterol ratio. Subsequent insulin administration temporarily negated the hyperglycemic effects of hydrocortisone, induced temporary hyperlactemia, and augmented the reduction in blood triglycerides.

CONCLUSIONS AND CLINICAL RELEVANCE

A single dose of a short-acting corticosteroid does not increase blood lipid fractions in healthy alpacas, probably because of a competent endogenous insulin response. Corticosteroids may induce differing responses in camelids with depleted glycogen stores or an ineffective insulin response. Administration of insulin can effectively negate the hyperglycemic effects of hydrocortisone and augment lipoprotein clearance. Hence, insulin administration may be therapeutic for alpacas with hyperglycemia, hyperlipemia, or hyperketonemia.

Evaluation of circulating levels and renal clearance of natural amino acids in patients with Cushing's disease

Although the hypercortisolism-induced impairment of protein homeostasis is object of several studies, a detailed evaluation of the complete amino acid profile of patients with Cushing's syndrome (CS) has never been performed. The aim of the current open transversal controlled study was to evaluate serum and urinary concentrations as well as renal clearance of the complete series of natural amino acids and their relationship with glucose tolerance in patients with Cushing's disease (CD). Twenty patients with CD (10 active and 10 cured) and 20 sex- and age-matched healthy controls entered the study. Measurement of serum and urinary levels of the complete series of natural amino acids was performed in all patients analyzed by cationic exchange high performance liquid cromatography (HPLC) after 2 weeks of a standardized protein intake regimen. The renal clearance (renal excretion rate) of each amino acid was calculated on the basis of the serum and urinary concentrations of creatinine and the specific amino acid. Fasting glucose and insulin levels, glucose and insulin response to standard glucose load, insulinogenic and homeostasis model insulin resistance (Homa-R) indexes were also evaluated and correlated to the circulating levels and renal clearances of each amino acid. Significantly higher serum (p<0.01) and urinary (p<0.05) levels of alanine and cystine, lower serum and higher urinary levels of leucine, isoleucine and valine (p<0.05) and higher renal excretion rates of leucine, isoleucine and valine (p<0.01) were found in patients with active CD than in patients cured from the disease and in controls. No difference was found between cured patients and controls. Creatinine clearance was similar in active and cured patients and in controls. In patients with active CD, urinary cortisol levels were significantly correlated to urinary cystine levels (r=0.85; p<0.01) and renal excretion rate of leucine (r=-0.76; p<0.05), isoleucine (r=-0.76; p<0.05) and valine (r=-0.66; p<0.05). Fasting blood glucose levels were significantly correlated to serum alanine levels (r=0.70; p<0.05). Although Homa-R was significantly correlated to BMI in active patients (r=0.74 p<0.05), it was not correlated to amino acid levels. In conclusion, the results of the current study demonstrate that patients with CD have significant changes in serum and urinary concentration of several amino acids and changes in renal clearance of some specific amino acids. Normalization of cortisol levels restored the amino acid profile.

Sense of coherence buffers relationships of chronic stress with fasting glucose levels

Sense of coherence (SOC) was examined as a buffer of the relationship of chronic stress with fasting glucose and insulin levels. Spouse caregivers of persons with diagnoses of Alzheimer's disease (AD) (n = 73) were compared to controls [spouses of nondemented persons (n = 69)], group-matched on age/gender. After controlling for anger and coronary heart disease (CHD), interactions of SOC and gender explained variance in glucose (but not insulin) at study entry (T1) and 15-18 months later (T2). However, this occurred only in caregivers. At both times SOC and glucose were negatively related in men caregivers but not in women caregivers or in controls. In caregivers (but not controls), SOC at T1 predicted glucose at T2, independent of gender, anger, and glucose at T1; and hassles at T1 appeared to mediate this relationship. Future research should examine SOC as a buffer of other chronic stressors and metabolic variables.

Insulin secretion and sensitivity in children on cyclic total parenteral nutrition

BACKGROUND

Some children receiving total parenteral nutrition (TPN) have abnormal glucose tolerance.

METHODS

Insulin secretion and sensitivity were studied in 12 patients, aged 5.7 to 19.4 years, receiving cyclic nocturnal TPN. Insulin secretion was measured during an IV glucose tolerance test (IVGTT; 0.5 g/kg) followed by a hyperglycemic clamp (plasma glucose at 10 mmol/L). Insulin sensitivity was assessed by hyperinsulinemic euglycemic clamp (insulin infusion = 1 mU/kg/min).

RESULTS

Patients with normal glucose tolerance receiving TPN had an insulin response to IVGTT similar to that of normal children of the same age. Insulin levels of TPN patients were higher than those in healthy young adults during the hyperglycemic clamp. Whole body glucose disposal was greater in younger than in older children (range, 7.1 to 25.2 mg/kg/min), and this inverse correlation with age was statistically significant (p < .01). Two patients with abnormal glucose tolerance showed a decreased capacity to release insulin, whereas insulin sensitivity was unchanged in one of these two patients. Two patients treated with prednisone or octreotide had insulin levels similar to those of normal TPN children.

CONCLUSIONS

The insulin response to sustained hyperglycemia was stronger in children with normal glucose tolerance on cyclic TPN. Patients with a limited capacity to release insulin, either constitutional or acquired, may not be able to produce enough insulin in these conditions and develop glucose intolerance during TPN. Insulin sensitivity was not a key factor in the alteration of glucose tolerance.

Effect of needle biopsy from the vastus lateralis muscle on insulin-stimulated glucose metabolism in humans

To examine the cellular mechanisms behind conditions characterized by insulin resistance, the clamp technique is often combined with muscle biopsies. To test whether the trauma of a needle biopsy from the vastus lateralis muscle per se may influence insulin-stimulated glucose uptake, eight healthy subjects underwent two randomly sequenced hyperinsulinemic (insulin infusion rate: 0.6 mU.kg-1.min-1 for 150 min) euglycemic clamps with an interval of 4-6 wk. In one study (study B) a muscle biopsy (approximately 250 mg, i.e., larger than normal standard) was taken in the basal state just before the clamp procedure, whereas the other was a control study (study C). Insulin-stimulated glucose uptake was significantly reduced in study B (5.36 +/- 0.96 mg.kg-1.min-1) compared with study C (6.06 +/- 0.68 mg.kg-1.min-1; P < 0.05). Nonoxidative glucose disposal (indirect calorimetry) was decreased (2.81 +/- 1.08 vs. 3.64 +/- 1.34 mg.kg-1.min-1; P < 0.05), whereas glucose oxidation was unaltered. Likewise, endogenous glucose output ([3-3H]glucose) was identically suppressed during hyperinsulinemia. Circulating levels of epinephrine, glucagon, and growth hormone did not differ significantly in studies B and C. In contrast, plasma norepinephrine, serum cortisol, and free fatty acid rose after biopsy (P < 0.05). In conclusion, performance of a muscle biopsy may diminish insulin sensitivity by affecting nonoxidative glucose metabolism. This should be considered when assessing whole body insulin sensitivity after a percutaneous needle muscle biopsy.

Impact of chronic stress hormone infusion on hepatic carbohydrate metabolism in the conscious dog

The effects of chronic administration of counterregulatory hormones on hepatic glycogenolysis and gluconeogenesis were investigated. We studied 14 20-h fasted conscious dogs prior to (day 0) and after a 70-h stress hormone (SHI, n = 7) or saline (n = 7) infusion (day 3). Glucose production and gluconeogenesis were assessed using tracer and arteriovenous difference techniques. SHI increased plasma glucagon, cortisol, epinephrine, and norepinephrine levels approximately fivefold. SHI increased the arterial plasma glucose and insulin concentrations (110 +/- 2 to 204 +/- 19 mg/dl and 13 +/- 2 to 36 +/- 3 microU/ml on day 3). Tracer-determined glucose appearance and net hepatic glucose output were increased 80 and 60%, respectively. Net hepatic lactate uptake and fractional extraction were increased by 11.2 +/- 3.8 and 0.51 +/- 0.18 mumol.kg-1 x min-1, respectively, as was net hepatic glycerol uptake (1.0 +/- 0.6 mumol.kg-1 x min-1). Net hepatic fractional alanine extraction was also increased by 0.37 +/- 0.03 mumol.kg-1 x min-1; however, net hepatic alanine uptake was not altered. The efficiency of alanine conversion to glucose almost doubled (0.33 +/- 0.05 to 0.59 +/- 0.09). Renal glucose production was also increased, accounting for 33% of the increase in glucose turnover. This increase was paralleled by an increase in renal gluconeogenic precursor uptake. In conclusion, SHI created marked hyperglycemia and hyperinsulinemia and elevated glucose production from both the liver and the kidney, with gluconeogenesis accounting for approximately 70% of the response.

Interaction of cortisol and epinephrine in the regulation of leucine kinetics in man

To assess the interaction of the two major stress hormones epinephrine and cortisol in the regulation of leucine kinetics in man, epinephrine (50 ng/kg/min) was infused either alone or in combination with cortisol (2 micrograms/kg/min) into two groups of 6 postabsorptive normal male subjects during 180 min. Plasma leucine concentrations decreased by 28% (p less than 0.05) from baseline during epinephrine treatment (plasma levels 515 pg/ml); this was due to a decrease of leucine appearance (determined by 1-13C-leucine infusions) by 23% (p less than 0.025); leucine oxidation decreased by 29% (p less than 0.05). However, when plasma cortisol concentrations were elevated to supraphysiological levels (16.3 mumol/l) during epinephrine administration, the decreases of leucine plasma concentrations, appearance and oxidation were abolished. Plasma glucose and FFA concentrations were similarly elevated during both kinds of treatment. Since leucine appearance represents a measurement of total body protein breakdown and leucine disappearance into non-oxidative pathways reflects protein synthesis, the data indicate that plasma epinephrine concentrations during severe stress exert a protein anabolic effect in man which may counteract catabolic properties of elevated plasma cortisol.

Impaired glucose handling in active rheumatoid arthritis: relationship to peripheral insulin resistance

Glucose metabolism was studied after an intravenous glucose loading in normal-weighted, previously untreated patients (n = 14) with active rheumatoid arthritis (RA). The patients displayed an enhanced insulin response and impaired glucose handling compared with healthy controls (P less than .001). The insulin sensitivity, measured as the glucose utilization rate during steady state of euglycemia (M) was significantly decreased (P less than .01) among the patients compared to the controls (5.5 +/- 1.9 mg/kg BW/min [mean +/- SD] and 7.2 +/- 1.2, respectively). The corresponding values for the metabolic clearance rate (MCR) were 5.8 +/- 0.6 mL/kg BW/min and 8.2 +/- 0.4, respectively (P less than .01). In the patient group the k value correlated with the peripheral insulin sensitivity (P less than .01), which, in turn, was inversely related to the acute phase reaction (P less than .05). During 1 week of potent anti-inflammatory treatment with corticosteroids (prednisolone 20 mg daily) the k value improved P less than .001), the insulin sensitivity tended to improve and the insulin response increased (P less than .001) after an intravenous glucose loading. Five patients who had a remission of their disease on sulphasalazine as antirheumatic therapy were reexamined. A normalization of the inflammatory activity as well as the glucose handling and insulin sensitivity was achieved. The data obtained indicate that impaired glucose handling in active RA is related to insulin resistance. The linkage between inflammatory indices and glucose metabolism might reflect a special consequence of inflammation, but the influence of nonspecific disease manifestations, ie, malnutrition, inactivity, and myopenia, has to be considered.

The effects of cortisol supplementation on the metabolic and hormonal response to surgery

The role of cortisol in determining the metabolic and hormonal changes associated with a standardized surgical operation was investigated. Twelve patients undergoing pelvic surgery were studied. Six received steroid supplementation with an infusion of hydrocortisone sodium succinate at a rate of 8 mg/h for 24 h, together with 1.5 g hydrocortisone acetate intraperitoneally at the completion of surgery, while the remainder acted as a control group. Steroid supplementation resulted in plasma cortisol values in the range 1913-2265 nmol/l from 4 to 24 h after the start of surgery. However, this marked hypercortisolaemia had no significant effects on circulating metabolites other than glucose, and did not alter plasma ACTH, GH and insulin values. The usual glycaemic response to surgery was significantly augmented by 1.0-1.5 mmol/l in the cortisol group. We conclude that changes in substrate mobilization observed after cortisol administration in normal volunteers may not accurately predict the effects found after surgery, when catabolic hormones and other modulators such as interleukin-1 may influence metabolism.

Prolonged insulin resistance following insulin-induced hypoglycaemia

Nineteen normal male volunteers underwent a 10-h glucose clamp study to examine the duration and mechanism of insulin resistance after hypoglycaemia. Dextrose delivery by the Biostator to maintain the target blood glucose level fell below baseline 2 h after induction of hypoglycaemia and remained suppressed for at least 7 h after insulin hypoglycaemia. Insulin secretion as manifested by C-peptide levels remained suppressed for 3-4 h after insulin hypoglycaemia despite return of blood glucose to baseline by 90 min. Glucose kinetic data (3-3H-glucose) performed in six of the subjects indicated that the prolonged insulin resistance was due to significantly increased hepatic glucose production and to suppressed glucose utilisation, persisting for at least 4 h after counterregulatory hormone levels had returned to normal. Post-hypoglycaemic insulin resistance as determined by dextrose delivery was markedly attenuated and the rise in hepatic glucose output totally eliminated in five hypopituitary subjects without growth hormone or cortisol responses to hypoglycaemia. We conclude that post-hypoglycaemic insulin resistance occurs in non-diabetic subjects and persists for at least 7 h following hypoglycaemia. This prolonged insulin resistance is largely related to release of growth hormone and cortisol.

Decreased insulin binding and antilipolytic response in adipocytes from patients with Cushing's syndrome

Human adipocytes from patients with chronic endogenous hypercortisolism (Cushing's syndrome) showed a statistically significant decrease in insulin binding at low unlabelled-insulin concentrations but no change in receptor numbers (Cushing's 180,000 +/- 48,000 (3) receptors/cell and controls 189,000 +/- 30,000 (7)) together with a fourfold decrease in apparent receptor affinity (ED50: Cushing's 2.25 x 10(-9) M and controls 0.57 x 10(-9) M) and a decreased sensitivity to the antilipolytic effect of insulin. These events could represent the final situation of a chronic and endogenous regulation by high levels of cortisol of insulin receptors in human adipose tissue.