Most often, diabetic ketoacidosis (DKA) in adults results from insufficient insulin administration and acute infection. DKA is assumed to release proinflammatory cytokines and stress hormones that stimulate lipolysis and ketogenesis. We tested whether this perception of DKA can be reproduced in an experimental human model by using combined insulin deficiency and acute inflammation and tested which intracellular mediators of lipolysis are affected in adipose tissue. Nine subjects with type 1 diabetes were studied twice: 1) insulin-controlled euglycemia and 2) insulin deprivation and endotoxin administration (KET). During KET, serum tumor necrosis factor-α, cortisol, glucagon, and growth hormone levels increased, and free fatty acids and 3-hydroxybutyrate concentrations and the rate of lipolysis rose markedly. Serum bicarbonate and pH decreased. Adipose tissue mRNA contents of comparative gene identification-58 (CGI-58) increased and G0/G1 switch 2 gene (G0S2) mRNA decreased robustly. Neither protein levels of adipose triglyceride lipase (ATGL) nor phosphorylations of hormone-sensitive lipase were altered. The clinical picture of incipient DKA in adults can be reproduced by combined insulin deficiency and endotoxin-induced acute inflammation. The precipitating steps involve the release of proinflammatory cytokines and stress hormones, increased lipolysis, and decreased G0S2 and increased CGI-58 mRNA contents in adipose tissue, compatible with latent ATGL stimulation.

Diabetic ketoacidosis (DKA) remains one of the most common, serious, and demanding medical emergencies within the field of diabetology. In Western societies, the annual frequency of DKA is ∼5% in patients with type 1 diabetes (1,2). A Scottish survey estimated that death from DKA is associated with the single largest percentage of the loss of life expectancy occurring before the age of 50 years, contributing to 25% of the excess mortality in this group of patients (3). The magnitude of these figures and the associated clinical challenges likely are much higher in developing areas with less advanced health care (4).

The most common precipitating factor of DKA in adults is lack of insulin and infection, leading to a vicious cycle with release of proinflammatory cytokines and counterregulatory hormones, increased lipolysis and ketogenesis, hyperosmolarity, and dehydration (5). This concept to some extent is based on observational studies showing increased levels of cytokines, stress hormones, and free fatty acids (FFAs) in patients with full-blown DKA; these changes possibly reflect rather than cause the metabolic disarrangement (6). Experimental studies primarily have used insulin withdrawal to assess the precipitating events in type 1 diabetic DKA. These studies have shown increased lipolysis/FFA availability and increased levels of glucagon to be important triggers of ketogenesis (79), whereas proinflammatory cytokines in general have not been measured, and levels of cortisol, epinephrine, and growth hormone (GH), when measured, have not been increased. Studies in subjects without diabetes have showed that administration of tumor necrosis factor-α (TNF-α) or endotoxin (lipopolysaccharide [LPS]), as a model for acute inflammation, increases circulating levels of stress hormones and stimulates lipolysis (1013).

Uncontrolled lipolysis plays a pivotal role in the pathogenesis of DKA by increasing the amount of FFAs reaching the liver and acting as precursors for ketogenesis. Lipolysis is controlled by adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and monoacylglycerol lipase, which hydrolyze triglycerides to FFAs and glycerol (14). ATGL activity is stimulated by comparative gene identification-58 (CGI-58) and inhibited by counterregulatory G0/G1 switch gene 2 (G0S2) (14).

The current study tested whether an experimental clinical model of DKA in subjects with type 1 diabetes is possible by combining exposure to acute inflammation (endotoxin/LPS) and insulin deficiency and whether this model would reproduce the whole spectrum of metabolic events observed in the clinical setting. In addition, we aimed to define precipitating intracellular adipocyte signaling events participating in this scenario, particularly modulation of ATGL.

Study Design and Protocol

We used a randomized controlled crossover design comprising two arms separated by at least 3 weeks: 1) euglycemic control condition (CTR) and 2) hyperglycemic ketotic condition (KET) induced by endotoxin administration plus insulin deprivation. Long-acting insulin was paused 24 h before each study day and replaced by rapid-acting insulin. Patients were hospitalized at 10:00 p.m., and subcutaneous insulin administration was changed to continuous intravenous administration (Actrapid; Novo Nordisk, Copenhagen, Denmark). An additional intravenous catheter was placed in a dorsal hand vein for blood glucose and ketone measurements overnight. During CTR, the subjects were given a variable amount of insulin, and blood glucose was kept at 5–7 mmol/L. During KET, the dose of insulin was reduced to 15% of the basal insulin requirements from 10:00 p.m. onward. A physician measured blood glucose every hour and ketone bodies (FreeStyle Precision; Abbott Diabetes Care) every second hour during the night. Studies were commenced at 0700 h (t = 0 min), and subjects were examined for 5 h. The dorsal hand vein was heated to arterialize the blood. Nine young male volunteers with type 1 diabetes were included after informed consent was obtained. The following inclusion criteria were used: type 1 diabetes (C-peptide negative), male sex, 20–40 years of age, no medication other than insulin, BMI 19–26 kg/m2, and no chronic diseases or diabetes complications. A medical examination and routine blood check were conducted; 13 subjects were screened and 9 were found eligible for inclusion.

The project was approved by the Danish Mid-Regional Ethics Committee (1-10-72-98-14) in accordance with the Declaration of Helsinki.

Endotoxin/LPS

Escherichia coli endotoxin (LPS) (10,000 USP Endotoxin, lot HOK354; U.S. Pharmacopeial Convention, Rockville, MD) was diluted in isotonic saline. A bolus of 1 ng/kg (10 units/kg) body weight was given intravenously at t = 0 min (0700 h).

Outcomes and Analytical Methods

Indirect calorimetry (Oxycon Pro; Intramedic, Gentofte, Denmark) was performed at t = 150 min to measure substrate oxidation rates as described by Ferrannini (15). Albumin-bound [9,10-3H]-palmitate (GE Healthcare, Brøndby, Denmark) was infused (0.3 μCi/min) at t = 200–260 min and analyzed in triplicate as previously described (9).

Abdominal subcutaneous adipose tissue biopsy specimens were obtained at t = 0 and t = 270 min and were immediately cleansed and snap-frozen in liquid nitrogen. Western blot analysis was performed using standard protocols and commercially available materials and antibodies (Supplementary Data).

Serum concentrations of FFA, cortisol, glucagon, GH, lactate, and C-peptide and plasma concentrations of TNF-α, interleukin (IL)-10, and IL-6 were quantified by routine assays as described previously (16). Serum concentrations of β-hydroxybutyrate (3-OHB) were measured using hydrophilic interaction liquid chromatography–tandem mass spectrometry (17).

mRNA was isolated using TRIzol (Gibco BRL; Life Technologies, Roskilde, Denmark), and quantitative PCR was performed in a LightCycler 480 (Roche). G0S2, ATGL, CGI-58, and cell death–inducing DFFA-like effector C and A (CIDEC/CIDEA) genes were quantified using the housekeeping gene GAPDH. GAPDH was tested and found to be equal in the two groups (Supplementary Data).

Statistics

Results are presented as mean ± SEM, unless otherwise specified. Normal distribution of data was ensured by inspection of Q–Q plots. Data were logarithmically transformed if the distribution was unequal. If data remained unequally distributed, a rank sum test was performed to test for differences between the two study days. Statistical association of the two study days was tested using a paired t test and two-way repeated-measures ANOVA when relevant. P < 0.05 was considered significant.

Subjects

The nine male volunteers reported variable degrees of chills, nausea, discomfort, and headache during KET. Symptoms peaked approximately at t = 120 min and persisted throughout the day. No serious adverse events occurred (Table 1).

Table 1

Subject characteristics

CharacteristicAll subjectsCTRKETP value
Baseline     
 HbA1c     
  % 7.7    
  mmol/mol 61    
 Diabetes duration (years) 14 ± 2    
 Daily insulin (IE/kg/day) 0.7 ± 0.4    
 Age (years) 30 (21–40)    
 BMI (kg/m225 ± 1    
Vital parameter     
 ΔTemperature (°C)  1.3 ± 0.3 2.7 ± 0.1 0.005 
 ΔPulse (beats/min)  13 ± 1 41 ± 2 <0.001 
 ΔRespiratory frequency (breaths/min)  1 ± 0 6 ± 1 0.01 
 ΔMean arterial pressure decrease (mmHg)  6 ± 2 13 ± 4 0.09 
Hormones and cytokines     
 ΔGH (ng/mL)  2.4 ± 2.6 10.6 ± 2.0 0.016 
 Glucagon (pg/mL)  38.9 ± 5.5 95.1 ± 18.8 0.011 
 ΔTNF-α (NF-1mL)  4.8 ± 1.6 798.4 ± 104.5 <0.001 
 ΔIL-6 (pg/mL)  11.7 ± 4.6 1,985.7 ± 250.9 <0.000 
 ΔIL-10 (pg/mL)  3.0 ± 0.7 85.6 ± 16.1 <0.001 
 ΔCortisol (ng/mL)  23 ± 20 161 ± 29 <0.001 
Arterial blood gas     
 pH  7.41 ± 0.004 7.39 ± 0.004 0.008 
 Lactate  0.90 ± 0.26 1.23 ± 0.27 0.02 
 HCO3 (mmol/L)  24.9 ± 0.33 22.7 ± 0.33 0.001 
CharacteristicAll subjectsCTRKETP value
Baseline     
 HbA1c     
  % 7.7    
  mmol/mol 61    
 Diabetes duration (years) 14 ± 2    
 Daily insulin (IE/kg/day) 0.7 ± 0.4    
 Age (years) 30 (21–40)    
 BMI (kg/m225 ± 1    
Vital parameter     
 ΔTemperature (°C)  1.3 ± 0.3 2.7 ± 0.1 0.005 
 ΔPulse (beats/min)  13 ± 1 41 ± 2 <0.001 
 ΔRespiratory frequency (breaths/min)  1 ± 0 6 ± 1 0.01 
 ΔMean arterial pressure decrease (mmHg)  6 ± 2 13 ± 4 0.09 
Hormones and cytokines     
 ΔGH (ng/mL)  2.4 ± 2.6 10.6 ± 2.0 0.016 
 Glucagon (pg/mL)  38.9 ± 5.5 95.1 ± 18.8 0.011 
 ΔTNF-α (NF-1mL)  4.8 ± 1.6 798.4 ± 104.5 <0.001 
 ΔIL-6 (pg/mL)  11.7 ± 4.6 1,985.7 ± 250.9 <0.000 
 ΔIL-10 (pg/mL)  3.0 ± 0.7 85.6 ± 16.1 <0.001 
 ΔCortisol (ng/mL)  23 ± 20 161 ± 29 <0.001 
Arterial blood gas     
 pH  7.41 ± 0.004 7.39 ± 0.004 0.008 
 Lactate  0.90 ± 0.26 1.23 ± 0.27 0.02 
 HCO3 (mmol/L)  24.9 ± 0.33 22.7 ± 0.33 0.001 

Data are mean ± SE or median (range) unless otherwise indicated. Baseline characteristics of the nine subjects and results are shown for CTR and KET. Δ = peak value during the trial (t = 0–300 min) − baseline value (t = 0 min). Vital parameters were measured every hour throughout the trial. Hormones and cytokines were measured at t = 0, 120, and 240 min. Arterial blood gases were measured at t = 120, 240, and 300 min. IE, islet equivalents.

Inflammation, Clinical Picture, and Stress Hormones

Blood concentrations of TNF-α, IL-6, IL-10, cortisol, glucagon, and GH were elevated during KET compared with CTR (P < 0.05). Respiratory rate, temperature, and heart rate were all significantly higher in KET (P < 0.02). Serum bicarbonate and pH decreased modestly (P < 0.001) (Table 1).

Substrate Concentrations

Blood glucose, lactate, FFA, and 3-OHB were higher (P < 0.03) and insulin was lower during KET than during CTR (P < 0.001) (Figs. 1 and 2 and Table 1).

Figure 1

Serum glucose (A) was measured every 30 min, and there was a highly significant main effect difference between the two study days. Serum insulin (B) was measured every 30 min, and there was a highly significant main effect difference between the two study days. Serum 3-OHB (C) was measured every hour, and there was a highly significant interaction difference between the two study days. Results are shown for nine subjects during CTR and KET. ●, KET day; ○, CTR day. Data are mean ± SE. Two-way repeated-measures ANOVA was used to test for differences between the two study days. #Significant main effect. $Significant interaction difference.

Figure 1

Serum glucose (A) was measured every 30 min, and there was a highly significant main effect difference between the two study days. Serum insulin (B) was measured every 30 min, and there was a highly significant main effect difference between the two study days. Serum 3-OHB (C) was measured every hour, and there was a highly significant interaction difference between the two study days. Results are shown for nine subjects during CTR and KET. ●, KET day; ○, CTR day. Data are mean ± SE. Two-way repeated-measures ANOVA was used to test for differences between the two study days. #Significant main effect. $Significant interaction difference.

Figure 2

Lipolysis was quantified through FFA, palmitate tracer flux (Ra), and indirect calorimetry to estimate energy expenditure and lipid oxidation rates. Results are shown for nine subjects during CTR and KET. Serum FFA (A) was measured toward the end of the trial at t = 270 min along with Ra (B) at t = 270 min. Energy expenditure (C) and lipid oxidation (D) were estimated by using indirect calorimetry at t = 150 min. Data are shown in dot plots, and the median value of CTR as reference = 1. A paired t test was used to test the difference between the two conditions.

Figure 2

Lipolysis was quantified through FFA, palmitate tracer flux (Ra), and indirect calorimetry to estimate energy expenditure and lipid oxidation rates. Results are shown for nine subjects during CTR and KET. Serum FFA (A) was measured toward the end of the trial at t = 270 min along with Ra (B) at t = 270 min. Energy expenditure (C) and lipid oxidation (D) were estimated by using indirect calorimetry at t = 150 min. Data are shown in dot plots, and the median value of CTR as reference = 1. A paired t test was used to test the difference between the two conditions.

Indirect Calorimetry and Palmitate Tracer

Energy expenditure increased 30% (560 kcal/day) and lipid oxidation rates increased by 50% (500 kcal/day) during KET (P < 0.001). The palmitate rate of appearance and serum palmitate concentrations were 2.5-fold higher during KET than during CTR (P < 0.001) (Fig. 2).

Protein and mRNA

Adipose tissue content of G0S2 mRNA was decreased fivefold (P = 0.002) and CGI-58 mRNA increased twofold (P = 0.01) during KET compared with CTR. The intracellular mRNA content of ATGL did not differ between the 2 days. CIDEC mRNA content was 40% lower (P = 0.03) during KET than during CTR (Fig. 3).

Figure 3

The intracellular G0S2 (A), CGI-58 (B), ATGL (C), and CIDEC (D) content of mRNA from adipose tissue biopsy specimens are shown for nine subjects during CTR at t = 0 min (CTR0) and 300 min (CTR300) and KET at t = 0 min (KET0) and 300 min (KET300). Two-way repeated-measures ANOVA and post hoc paired t test were used to test for a difference between the biopsy specimens. Data are shown as dot plots and ratios, and the median value of CTR0 as reference = 1. #P < 0.03, KET300 vs. CTR0; £P < 0.001, KET300 vs. CTR300; ¥P < 0.002, KET300 vs. KET0; ₠P < 0.05, KET0 vs. CTR0.

Figure 3

The intracellular G0S2 (A), CGI-58 (B), ATGL (C), and CIDEC (D) content of mRNA from adipose tissue biopsy specimens are shown for nine subjects during CTR at t = 0 min (CTR0) and 300 min (CTR300) and KET at t = 0 min (KET0) and 300 min (KET300). Two-way repeated-measures ANOVA and post hoc paired t test were used to test for a difference between the biopsy specimens. Data are shown as dot plots and ratios, and the median value of CTR0 as reference = 1. #P < 0.03, KET300 vs. CTR0; £P < 0.001, KET300 vs. CTR300; ¥P < 0.002, KET300 vs. KET0; ₠P < 0.05, KET0 vs. CTR0.

Western blot analysis of the adipose tissue biopsy specimens did not reveal significant differences in expression of ATGL, G0S2, CGI-58, and CIDEC (data not shown). In addition, phosphorylated HSL Ser552, 554, 650, PKA-substrate/PLIN1, phosphorylated Akt Ser473, Akt, phosphorylated AS160 Thr642, AS160, and CIDEA remained unaltered.

This study was designed to create an experimental clinical model of DKA in subjects with type 1 diabetes by combining endotoxin/LPS exposure (infection/inflammation) and insulin deficiency and to assess whether such a model replicates the entire metabolic disarray observed in the clinical setting of DKA. This approach succeeded in replicating both the high levels of cytokines, stress hormones, FFA, and 3-OHB observed clinically and the increased rate of lipolysis observed when experimental insulin deprivation is used as a DKA model, confirming that all these factors are involved in the pathogenesis of DKA. In addition, we found decreased G0S2 and increased CGI-58 adipose tissue contents of mRNA, suggesting incipient ATGL activation, which together with decreased CIDEC mRNA expression, may lead to increased lipolysis (14).

These findings cement the prevailing notion that in general, DKA in adults is caused by insulin deficiency and the presence of acute inflammation, triggering the release of proinflammatory cytokines and stress hormones, all of which modulate intracellular adipose tissue signaling and eventually lead to uncontrolled lipolysis and ketogenesis (5). As outlined previously (6), proinflammatory cytokines likely play a key role either as primary agents in the case of acute inflammation by infection or as secondary agents in the absence of obvious infection. At some stage, this will activate the hypothalamo-pituitary axis and release stress hormones (10). In human studies, TNF-α (11), IL-6 (18), epinephrine (19), cortisol, and GH (20) coherently increase lipolysis, and glucagon augments ketogenesis when the FFA concentration is increased (8). One study suggested that the lipolytic response to TNF-α is markedly dampened in patients with hypopituitarism without cortisol and GH responses, underlining the importance of intact pituitary function and stress hormone release for maximum stimulation of lipolysis to occur (13).

In subjects without diabetes, the dose of endotoxin used in the current study has previously been shown to cause increments in inflammatory cytokines and stress hormones and a less pronounced peak increase in 3-OHB (170 vs. 1,500 μmol/L in the current study) and FFA (650 vs. 1,200 μmol/L) (16). A previous study using interruption of continuous subcutaneus insulin infusion for 6 h in subjects with type 1 diabetes reported slightly lower peak values of 3-OHB of around 900–1,000 μmol/L (21). Although we observed marked increments in 3-OHB and FFA, together with modest decreases in pH and plasma bicarbonate, patients admitted for full-blown DKA generally have at least two- to threefold higher 3-OHB levels and are more acidotic.

We did not observe detectable alterations of the phosphorylation of HSL or the protein expression of ATGL, G0S2, and CGI-58. The lack of protein alterations could be due to a negative feedback mechanism involving 3-OHB—and perhaps also lactate—inhibition of lipases and lipolysis (22,23). Human studies have shown an ∼40% reduction of lipolysis after 3-OHB infusion (24). On the other hand, the current findings of increased CGI-58 mRNA and decreased and unaltered CGI-58 protein and decreased intracellular mRNA expression of G0S2 are compatible with latent ATGL stimulation. In addition, the decreased CIDEC mRNA contents in adipose tissue suggests that decreased CIDEC activity may participate in stimulation of lipolysis (14). Of note, we observed a minor decrease in blood glucose 1–2 h after endotoxin administration; endotoxin has been reported to acutely increase glucose disposal, perhaps related to TNF-α and IL-6 actions (25).

The current study design has limitations. Adipose biopsy specimens were obtained from subcutaneous abdominal depots 5 h after endotoxin exposure, and the results may have been different if the biopsy specimens had been taken at other time points and/or from other locations. We only observed relatively modest increments in 3-OHB levels, implying that the findings only apply to the initial precipitating events triggering DKA.

In conclusion, we show that a combination of insulin deficiency and endotoxin-induced acute inflammation can be used as a model to mimic the clinical picture of incipient DKA and that the precipitating events involve release of proinflammatory cytokines and stress hormones. The increased lipolysis is associated with decreased G0S2 and increased CGI-58 mRNA contents in adipose tissue, suggesting latent ATGL activation.

Clinical trial reg. no. NCT02157155, clinicaltrials.gov.

Acknowledgments. The authors thank Annette Mengel, Karen Mathiassen, Eva Schriver, Lenette Pedersen, and Helle Zibrandtsen from the Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark, for technical assistance and consistent work throughout the study. The authors also thank the nine subjects for participation and completion of the study days.

Funding. This work was funded by the Danish Council for Strategic Research (grant no. 0603-00479B).

Duality of Interest. No potential conflicts of interest relevant to this article were reported.

Author Contributions. M.S. contributed to the research design and conduct, data analysis, and writing and final approval of the manuscript. U.K. and P.L.P. contributed to the research design and final approval of the manuscript. T.V. and N.R. contributed to the research design and conduct and final approval of the manuscript. S.B.P., M.J., T.S.N., and N.J. contributed to the data analysis and final approval of the manuscript. N.M. contributed to the research design, data analysis, and writing and final approval of the manuscript. N.M. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

1.
Karges
B
,
Rosenbauer
J
,
Holterhus
PM
, et al.;
DPV Initiative
.
Hospital admission for diabetic ketoacidosis or severe hypoglycemia in 31,330 young patients with type 1 diabetes
.
Eur J Endocrinol
2015
;
173
:
341
350
[PubMed]
2.
Maahs
DM
,
Hermann
JM
,
Holman
N
, et al.;
National Paediatric Diabetes Audit and the Royal College of Paediatrics and Child Health, the DPV Initiative, and the T1D Exchange Clinic Network
.
Rates of diabetic ketoacidosis: international comparison with 49,859 pediatric patients with type 1 diabetes from England, Wales, the U.S., Austria, and Germany
.
Diabetes Care
2015
;
38
:
1876
1882
[PubMed]
3.
Livingstone
SJ
,
Levin
D
,
Looker
HC
, et al.;
Scottish Diabetes Research Network Epidemiology Group
;
Scottish Renal Registry
.
Estimated life expectancy in a Scottish cohort with type 1 diabetes, 2008-2010
.
JAMA
2015
;
313
:
37
44
[PubMed]
4.
Muyer
MT
,
Buntinx
F
,
Mapatano
MA
,
De Clerck
M
,
Truyers
C
,
Muls
E
.
Mortality of young patients with diabetes in Kinshasa, DR Congo
.
Diabet Med
2010
;
27
:
405
411
5.
Kitabchi
AE
,
Umpierrez
GE
,
Miles
JM
,
Fisher
JN
.
Hyperglycemic crises in adult patients with diabetes
.
Diabetes Care
2009
;
32
:
1335
1343
[PubMed]
6.
Stentz
FB
,
Umpierrez
GE
,
Cuervo
R
,
Kitabchi
AE
.
Proinflammatory cytokines, markers of cardiovascular risks, oxidative stress, and lipid peroxidation in patients with hyperglycemic crises
.
Diabetes
2004
;
53
:
2079
2086
[PubMed]
7.
Miles
JM
,
Rizza
RA
,
Haymond
MW
,
Gerich
JE
.
Effects of acute insulin deficiency on glucose and ketone body turnover in man: evidence for the primacy of overproduction of glucose and ketone bodies in the genesis of diabetic ketoacidosis
.
Diabetes
1980
;
29
:
926
930
[PubMed]
8.
Miles
JM
,
Haymond
MW
,
Nissen
SL
,
Gerich
JE
.
Effects of free fatty acid availability, glucagon excess, and insulin deficiency on ketone body production in postabsorptive man
.
J Clin Invest
1983
;
71
:
1554
1561
[PubMed]
9.
Moller
N
,
Jensen
MD
,
Rizza
RA
,
Andrews
JC
,
Nair
KS
.
Renal amino acid, fat and glucose metabolism in type 1 diabetic and non-diabetic humans: effects of acute insulin withdrawal
.
Diabetologia
2006
;
49
:
1901
1908
[PubMed]
10.
Van der Poll
T
,
Romijn
JA
,
Endert
E
,
Borm
JJ
,
Büller
HR
,
Sauerwein
HP
.
Tumor necrosis factor mimics the metabolic response to acute infection in healthy humans
.
Am J Physiol
1991
;
261
:
E457
E465
[PubMed]
11.
Plomgaard
P
,
Fischer
CP
,
Ibfelt
T
,
Pedersen
BK
,
van Hall
G
.
Tumor necrosis factor-alpha modulates human in vivo lipolysis
.
J Clin Endocrinol Metab
2008
;
93
:
543
549
[PubMed]
12.
Buhl
M
,
Bosnjak
E
,
Vendelbo
MH
, et al
.
Direct effects of locally administered lipopolysaccharide on glucose, lipid, and protein metabolism in the placebo-controlled, bilaterally infused human leg
.
J Clin Endocrinol Metab
2013
;
98
:
2090
2099
[PubMed]
13.
Bach
E
,
Møller
AB
,
Jørgensen
JO
, et al
.
Intact pituitary function is decisive for the catabolic response to TNF-α: studies of protein, glucose and fatty acid metabolism in hypopituitary and healthy subjects
.
J Clin Endocrinol Metab
2015
;
100
:
578
586
[PubMed]
14.
Nielsen
TS
,
Jessen
N
,
Jørgensen
JO
,
Møller
N
,
Lund
S
.
Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease
.
J Mol Endocrinol
2014
;
52
:
R199
R222
[PubMed]
15.
Ferrannini
E
.
The theoretical bases of indirect calorimetry: a review
.
Metabolism
1988
;
37
:
287
301
[PubMed]
16.
Rittig
N
,
Bach
E
,
Thomsen
HH
, et al
.
Amino acid supplementation is anabolic during the acute phase of endotoxin-induced inflammation: a human randomized crossover trial
.
Clin Nutr
.
2015
April 9 [Epub ahead of print]. doi:10.1016/j.clnu.2015.03.021
[PubMed]
17.
Sørensen
LK
,
Rittig
NF
,
Holmquist
EF
, et al
.
Simultaneous determination of β-hydroxybutyrate and β-hydroxy-β-methylbutyrate in human whole blood using hydrophilic interaction liquid chromatography electrospray tandem mass spectrometry
.
Clin Biochem
2013
;
46
:
1877
1883
[PubMed]
18.
Petersen
EW
,
Carey
AL
,
Sacchetti
M
, et al
.
Acute IL-6 treatment increases fatty acid turnover in elderly humans in vivo and in tissue culture in vitro
.
Am J Physiol Endocrinol Metab
2005
;
288
:
E155
E162
[PubMed]
19.
Baltzan
MA
,
Andres
R
,
Cader
G
,
Zierler
KL
.
Effects of epinephrine on forearm blood flow and metabolism in man
.
J Clin Invest
1965
;
44
:
80
92
[PubMed]
20.
Djurhuus
CB
,
Gravholt
CH
,
Nielsen
S
,
Pedersen
SB
,
Møller
N
,
Schmitz
O
.
Additive effects of cortisol and growth hormone on regional and systemic lipolysis in humans
.
Am J Physiol Endocrinol Metab
2004
;
286
:
E488
E494
[PubMed]
21.
Attia
N
,
Jones
TW
,
Holcombe
J
,
Tamborlane
WV
.
Comparison of human regular and lispro insulins after interruption of continuous subcutaneous insulin infusion and in the treatment of acutely decompensated IDDM
.
Diabetes Care
1998
;
21
:
817
821
[PubMed]
22.
Senior
B
,
Loridan
L
.
Direct regulatory effect of ketones on lipolysis and on glucose concentrations in man
.
Nature
1968
;
219
:
83
84
[PubMed]
23.
Liu
C
,
Wu
J
,
Zhu
J
, et al
.
Lactate inhibits lipolysis in fat cells through activation of an orphan G-protein-coupled receptor, GPR81
.
J Biol Chem
2009
;
284
:
2811
2822
[PubMed]
24.
Mikkelsen
KH
,
Seifert
T
,
Secher
NH
,
Grøndal
T
,
van Hall
G
.
Systemic, cerebral and skeletal muscle ketone body and energy metabolism during acute hyper-D-β-hydroxybutyratemia in post-absorptive healthy males
.
J Clin Endocrinol Metab
2015
;
100
:
636
643
[PubMed]
25.
van der Crabben
SN
,
Blümer
RM
,
Stegenga
ME
, et al
.
Early endotoxemia increases peripheral and hepatic insulin sensitivity in healthy humans
.
J Clin Endocrinol Metab
2009
;
94
:
463
468
[PubMed]

Supplementary data