Acute Insulin Resistance in Myocardial Ischemia: Causes and Consequences

Elevation of White Blood Cell Subtypes in Adult Trauma Patients with Stress-Induced Hyperglycemia

BACKGROUND

Blood immune cell subset alterations following trauma can indicate a patient's immune-inflammatory status. This research explored the influence of stress-induced hyperglycemia (SIH) on platelet counts and white blood cell (WBC) subtypes, including the derived indices of the monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR), in trauma patients.

METHODS

We studied 15,480 adult trauma patients admitted from 1 January 1998 to 31 December 2022. They were categorized into four groups: nondiabetic normoglycemia (NDN, n = 11,602), diabetic normoglycemia (DN, n = 1750), SIH (n = 716), and diabetic hyperglycemia (DH, n = 1412). A propensity score-matched cohort was formed after adjusting for age, sex, and comorbidities, allowing for comparing the WBC subtypes and platelet counts.

RESULTS

Patients with SIH exhibited significantly increased counts of monocytes, neutrophils, and lymphocytes in contrast to NDN patients. However, no significant rise in platelet counts was noted in the SIH group. There were no observed increases in these cell counts in either the DN or DH groups.

CONCLUSIONS

Our results demonstrated that trauma patients with SIH showed significantly higher counts of monocytes, neutrophils, and lymphocytes when compared to NDN patients, whereas the DN and DH groups remained unaffected. This underscores the profound association between SIH and elevated levels of specific WBC subtypes.

Association of Stress-Induced Hyperglycemia and Diabetic Hyperglycemia with Mortality in Patients with Traumatic Brain Injury: Analysis of a Propensity Score-Matched Population

Background: Hyperglycemia at the time of hospital admission is associated with higher morbidity and mortality rates in patients with traumatic brain injury (TBI). Using data from the Chang Gung Research Database (CGRD), this study aimed to compare mortality outcomes between patients with stress-induced hyperglycemia (SIH), diabetic hyperglycemia (DH), and nondiabetic normoglycemia (NDN). The study occurred at Keelung, Linkou, Chiayi, and Kaohsiung Chang Gung Memorial Hospitals (CGMHs). Methods: A total of 1166, 6318, 3622, and 5599 health records from Keelung, Linkou, Chiayi, and Kaohsiung CGMHs, respectively, were retrieved from the CGRD for hospitalized patients with TBI between January 2001 and December 2015. After propensity score matching for sex, age, and Glasgow Coma Scale (GCS) score, the matched cohorts were compared to evaluate differences in the primary outcome between patients with SIH, DH, and NDN. In-hospital mortality was the primary outcome. Results: The analysis of matched patient populations revealed that at the Kaohsiung CGMH, patients with SIH had 1.63-fold (95% CI: 1.09–2.44; p = 0.017) and 1.91-fold (95% CI: 1.12–3.23; p = 0.017) higher odds of mortality than patients with NDN and DH, respectively. Similar patterns were found at the Linkou CGMH; patients with SIH had higher odds of mortality than patients with NDN and DH. In contrast, at the Keelung CGMH, patients with SIH had significantly higher odds of mortality than those with NDN (OR: 3.25; 95% CI: 1.06–9.97; p = 0.039). At the Chiayi CGMH, there were no significant differences in mortality rates among all groups. Conclusions: This study’s results suggest that SIH and DH differ in their effect on the outcomes of patients with TBI. The results were similar between medical centers but not nonmedical centers; in the medical centers, patients with SIH had significantly higher odds of mortality than patients with either NDN or DH.

Dynamics of testosterone levels in patients with newly detected glucose abnormalities and acute myocardial infarction

OBJECTIVE

Low testosterone has been associated with increased cardiovascular risk and glucose abnormalities. This study explored the prevalence of low testosterone, dynamics over time and prognostic implications in acute myocardial infarction patients with or without glucose abnormalities.

METHODS

Male acute myocardial infarction patients (n = 123) and healthy controls (n = 124) were categorised as having normal or abnormal glucose tolerance (impaired glucose tolerance or diabetes) by oral glucose tolerance testing. Testosterone was measured at hospital admission, discharge, 3 and 12 months thereafter in patients. Patients and controls were followed for 11 years for major cardiovascular events (cardiovascular death/acute myocardial infarction/stroke/severe heart failure).

RESULTS

At hospital admission, more patients had low testosterone (⩽300 ng/dl) and lower median levels than controls (64 vs 28%; p < 0.001 and 243 vs 380 ng/dl; p < 0.01). At the subsequent time points, testosterone had increased to 311, 345 and 357 ng/dl. Patients with abnormal glucose tolerance had the highest prevalence (75%) of low levels. In adjusted Cox regression models, neither total nor free testosterone predicted major cardiovascular events.

CONCLUSION

Low testosterone levels were common in male acute myocardial infarction patients in the acute phase, especially in the presence of abnormal glucose tolerance, but increased over time indicating that testosterone measured in close proximity to acute myocardial infarction should be interpreted with caution.

Mortality Rate Associated with Admission Hyperglycemia in Traumatic Femoral Fracture Patients Is Greater Than Non-Diabetic Normoglycemic Patients but Not Diabetic Normoglycemic Patients

Background: Admission hyperglycemia is associated with increased morbidity and mortality in trauma patients. However, admission hyperglycemia is not only associated with stress-induced hyperglycemia (SIH) but also with diabetic hyperglycemia (DH); furthermore, patients with normoglycemia may not only have non-diabetic normoglycemia (NDN) but also have a possibility of diabetic normoglycemia (DN), with the diabetes under control. This study aimed to assess the effects of SIH and DH on the mortality outcomes of traumatic femoral fracture patients with NDN and DN. Methods: Admission hyperglycemia was diagnosed as a serum glucose ≥200 mg/dL upon arrival at the emergency department. Diabetes mellitus (DM) was determined by patient history and/or admission HbA1c ≥ 6.5%. DH and SIH were diagnosed by admission hyperglycemia in patients with and without DM. DN and NDN were determined by absence of admission hyperglycemia in patients with and without DM. These patients were allocated into four groups: SIH (n = 75), DH (n = 280), DN (n = 309), and NDN (n = 1326), with detailed information retracted from the Trauma Registry System at a level I trauma center between 1 January 2009, and 31 December 2016. Patients with incomplete registered data were excluded. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for mortality were estimated through a stepwise model selection of a multiple regression model that was adjusted by controlling the cofounding variables such age, sex, co-morbidities, and Injury Severity Score. Results: Compared to NDN, a 9.8-fold (95% CI 1.54–62.05; p = 0.016) and a 5.8-fold (95% CI 1.46–22.67; p = 0.012) increase in the adjusted mortality odds ratio of patients with SIH and DH, respectively, were found in this study. In addition, the adjusted odds of mortality between SIH (AOR = 0.3; 95% CI 0.03–2.99; p = 0.302) as well as DH patients (AOR = 0.6; 95% CI 0.20–1.89; p = 0.394) and DN patients had no significant difference. Conclusions: This study demonstrated that SIH and DH patients with traumatic femoral fractures had higher mortality when compared with NDN patients, but not when compared with DN patients, with or without adjustment of the differences in patient’s age, sex, co-morbidities, and injury severity.

Stress-Induced Hyperglycemia, but Not Diabetic Hyperglycemia, Is Associated with Higher Mortality in Patients with Isolated Moderate and Severe Traumatic Brain Injury: Analysis of a Propensity Score-Matched Population

Background: Admission hyperglycemia is associated with higher morbidity and mortality in patients with traumatic brain injury (TBI). Stress-induced hyperglycemia (SIH), a form of hyperglycemia induced by the stress response, is associated with increased patient mortality following TBI. However, admission hyperglycemia occurs not only in SIH but also in patients with diabetic hyperglycemia (DH). Current information regarding whether trauma patients with SIH represent a distinct group with differential outcomes compared to those with DH remains limited. Methods: Serum glucose concentration ≥200 mg/dL upon arrival at the emergency department was defined as hyperglycemia. Presence of diabetes mellitus (DM) was determined by patient history and/or admission glycated hemoglobin (HbA1c) level ≥6.5%. In the present study, the patient cohort included those with moderate and severe TBI, as defined by an Abbreviated Injury Scale (AIS) score ≥3 points in the head, and excluded those who had additional AIS scores ≥3 points in any other region of the body. A total of 1798 adult patients with isolated moderate to severe TBI were allocated into four groups: SIH (n = 140), DH (n = 187), diabetic normoglycemia (DN, n = 186), and non-diabetic normoglycemia (NDN, n = 1285). Detailed patient information was retrieved from the Trauma Registry System at a level I trauma center between 1 January 2009, and 31 December 2015. Unpaired Student’s t- and Mann–Whitney U-tests were used to analyze normally and non-normally distributed continuous data, respectively. Categorical data were compared using the Pearson chi-square or two-sided Fisher’s exact tests. Matched patient populations were allocated in a 1:1 ratio according to propensity scores calculated by NCSS software. Logistic regression was used to evaluate the effect of SIH and DH on the adjusted mortality outcome. Results: In patients with isolated moderate to severe TBI, the presence of SIH and DH led to 9.1-fold and 2.3-fold higher odds of mortality, respectively, than patients with NDN. After adjusting for confounding factors, including sex and age, pre-existing co-morbidities, existence of different kinds of intracerebral hemorrhage, and injury severity, patients with SIH still had 6.6-fold higher odds of mortality than those with NDN; however, DH did not present significantly higher adjusted mortality odds. SIH and DH presented different effects on outcomes after TBI. The results also suggested that the pathophysiological effect associated with SIH was different from that of DH. Conclusions: This study demonstrated that patients with SIH and DH had significantly higher mortality than patients with NDN. However, the adjusted mortality was significantly higher only in the selected propensity score-matched patients with SIH and not in those with DH.

Higher Mortality in Trauma Patients Is Associated with Stress-Induced Hyperglycemia, but Not Diabetic Hyperglycemia: A Cross-Sectional Analysis Based on a Propensity-Score Matching Approach

Background: Stress-induced hyperglycemia (SIH) is a form of hyperglycemia secondary to stress and commonly occurs in patients with trauma. Trauma patients with SIH have been reported to have an increased risk of mortality. However, information regarding whether these trauma patients with SIH represent a distinct group with differential outcomes when compared to those with diabetic hyperglycemia (DH) remains limited. Methods: Diabetes mellitus (DM) was determined by patient history and/or admission glycated hemoglobin (HbA1c) ≥6.5%. Non-diabetic normoglycemia (NDN) was determined by a serum glucose level <200 mg/dL in the patients without DM. Diabetic normoglycemia (DN) was determined by a serum glucose level <200 mg/dL in the patients with DM. DH and SIH was diagnosed by a serum glucose level ≥200 mg/dL in the patients with and without DM, respectively. Detailed data of these four groups of hospitalized patients, which included NDN (n = 7806), DN (n = 950), SIH (n = 493), and DH (n = 897), were retrieved from the Trauma Registry System at a level I trauma center between 1 January 2009 and 31 December 2015. Patients with incomplete registered data were excluded. Categorical data were compared with Pearson chi-square tests or two-sided Fisher exact tests. The unpaired Student's t-test and the Mann-Whitney U-test were used to analyze normally distributed continuous data and non-normally distributed data, respectively. Propensity-score-matched cohorts in a 1:1 ratio were allocated using NCSS software with logistic regression to evaluate the effect of SIH and DH on the outcomes of patients. Results: The SIH (median [interquartile range: Q1-Q3], 13 [9-24]) demonstrated a significantly higher Injury Severity Score (ISS) than NDN (9 [4-10]), DN (9 [4-9]), and DH (9 [5-13]). SIH and DH had a 12.3-fold (95% confidence interval [CI] 9.31-16.14; p < 0.001) and 2.4-fold (95% CI 1.71-3.45; p < 0.001) higher odds of mortality, respectively, when compared to NDN. However, in the selected propensity-score-matched patient population, SIH had a 3.0-fold higher odd ratio of mortality (95% CI 1.96-4.49; p < 0.001) than NDN, but DH did not have a significantly higher mortality (odds ratio 1.2, 95% CI 0.99-1.38; p = 0.065). In addition, SIH had 2.4-fold higher odds of mortality (95% CI 1.46-4.04; p = 0.001) than DH. These results suggest that the characteristics and injury severity of the trauma patients contributed to the higher mortality of these patients with hyperglycemia upon admission, and that the pathophysiological effect of SIH was different from that of DH. Conclusions: Although there were worse mortality outcomes among trauma patients presenting with hyperglycemia, this effect was only seen in patients with SIH, but not DH when controlling for age, sex, pre-existed co-morbidities, and ISS.

Acute Hepatic Insulin Resistance Contributes to Hyperglycemia in Rats Following Myocardial Infarction

Although hyperglycemia is common in patients with acute myocardial infarction (MI), the underlying mechanisms are largely unknown. Insulin signaling plays a key role in the regulation of glucose homeostasis. In this study, we test the hypothesis that rapid alteration of insulin signaling pathways could be a potential contributor to acute hyperglycemia after MI. Male rats were used to produce MI by ligation of the left anterior descending coronary artery. Plasma glucose and insulin levels were significantly higher in MI rats than those in controls. Insulin-stimulated tyrosine phosphorylation of insulin receptor substrate 1 (IRS1) was reduced significantly in the liver tissue of MI rats compared with controls, followed by decreased attachment of phosphatidylinositol 3-kinase (PI3K) p85 subunit with IRS1 and Akt phosphorylation. However, insulin-stimulated signaling was not altered significantly in skeletal muscle after MI. The relative mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and G6Pase were slightly higher in the liver tissue of MI rats than those in controls. Rosiglitazone (ROSI) markedly restored hepatic insulin signaling, inhibited gluconeogenesis and reduced plasma glucose levels in MI rats. Insulin resistance develops rapidly in liver but not skeletal muscle after MI, which contributes to acute hyperglycemia. Therapy aimed at potentiating hepatic insulin signaling may be beneficial for MI-induced hyperglycemia.

Effective glycaemic control critically determines insulin cardioprotection against ischaemia/reperfusion injury in anaesthetized dogs

AIMS

Experimental evidence has shown significant cardioprotective effects of insulin, whereas clinical trials produced mixed results without valid explanations. This study was designed to examine the effect of hyperglycaemia on insulin cardioprotective action in a preclinical large animal model of myocardial ischaemia/reperfusion (MI/R).

METHODS AND RESULTS

Anaesthetized dogs were subjected to MI/R (30 min/4 h) and randomized to normal plasma insulin/euglycaemia (NI/NG), normal-insulin/hyperglycaemia (NI/HG), high-insulin/euglycaemia (HI/NG), and high-insulin/hyperglycaemia (HI/HG) achieved by controlled glucose/insulin infusion. Endogenous insulin production was abolished by peripancreatic vessel ligation. Compared with the control animals (NI/NG), hyperglycaemia (NI/HG) significantly aggravated MI/R injury. Insulin elevation at clamped euglycaemia (HI/NG) protected against MI/R injury as evidenced by reduced infarct size, decreased necrosis and apoptosis, and alleviated inflammatory and oxidative stress (leucocyte infiltration, myeloperoxidase, and malondialdehyde levels). However, these cardioprotective effects of insulin were markedly blunted in hyperglycaemic animals (HI/HG). In vitro mechanistic study in neonatal rat cardiomyocytes revealed that insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and Akt was significantly attenuated by high glucose, accompanied by markedly increased IRS-1 O-GlcNAc glycosylation following hypoxia/reoxygenation. Inhibition of hexosamine biosynthesis with 6-diazo-5-oxonorleucine abrogated high glucose-induced O-GlcNAc modification and inactivation of IRS-1/Akt as well as cell injury.

CONCLUSIONS

Our results, derived from a canine model of MI/R, demonstrate that hyperglycaemia blunts insulin protection against MI/R injury via hyperglycaemia-induced glycosylation and subsequent inactivation of insulin-signalling proteins. Our findings suggest that prevention of hyperglycaemia is critical for achieving maximal insulin cardioprotection for the ischaemic/reperfused hearts.

Insulin resistance and inflammation markers in myocardial infarction

Background

Insulin resistance (IR) is known to be characteristic of type 2 diabetes mellitus, and is regarded as an important mechanism in disease pathogenesis. One of the key pathogenetic mechanisms of IR progression is impaired free fatty acid (FFA) metabolism. Plasminogen-activator inhibitor 1 (PAI-1) and key inflammation markers, ie, interleukin 6 (IL-6) and C-reactive protein (CRP), also play a role.

Purpose

To assess the changing levels of the metabolic proinflammation IR markers IL-6, CRP and PAI-1 and their association with the presence or absence of type 2 diabetes mellitus in myocardial infarction (MI) patients during their hospital stay.

Methods

The patients were divided into two groups: group 1 included 95 nondiabetic MI patients, and group 2 enrolled 40 diabetic MI patients. The control group consisted of 30 sex-and age-matched volunteers. Serum IL-6 and CRP levels as well as FFA, glucose, C-peptide, insulin, and plasma PAI-1 concentrations were measured at days 1 and 12 from MI onset.

Results

At day 1, there was an increase in glucose concentrations, which remained high in both groups by day 12 but was much higher in the diabetic patients. Basal insulin and C-peptide levels did not differ significantly from those in the control group. The quantitative insulin sensitivity-check index in both groups was significantly different from that in controls. FFA concentrations at day 1 in both diabetic and nondiabetic patients increased; by day 12, they had decreased but were still higher than the controls. CRP and IL-6 levels at day 1 were higher in all the patients, but diabetic patients had the highest levels; by day 12, the levels were lower but still 2.4-fold (IL-6) and 12.5-fold (CRP) higher than those in the control group.

Conclusion

This study showed that MI is accompanied both by activated inflammatory response and IR. Strong correlations between IL-6 and FFA concentrations demonstrate that nonspecific inflammation factors are involved in IR development in MI patients. Consequently, these inflammatory cytokines might cause the development of IR.

Beta-cell dysfunction and insulin resistance after subarachnoid haemorrhage

BACKGROUND

Hyperglycaemia is a common finding and an independent risk factor for increased morbidity and mortality in aneurysmal subarachnoid haemorrhage (SAH). Although in these patients hyperglycaemia is commonly ascribed to insulin resistance, there is little understanding of underlying mechanisms.

AIMS

To prospectively study temporal disturbances of glucose metabolism after aneurysmal SAH in patients without known abnormalities of glucose metabolism and to explore possible correlations with markers of stress.

METHODS

In consecutive aneurysmal SAH patients not subjected to insulin therapy, in-hospital and follow-up oral glucose tolerance tests (OGTTs) and assessments of insulin resistance, pancreatic β-cell function, free fatty acids (FFA) and cortisol were performed and compared with reference values.

RESULTS

We included 13 patients. In the first 2 weeks of admission, median fasting glucose and FFA levels were elevated while insulin levels were not. OGTTs were indicative of glucose intolerance in all patients at days 3 and 7, while on follow-up 1 patient had glucose intolerance and all patients had normal fasting glucose levels. Pancreatic β-cell function was impaired throughout the first week and insulin resistance from day 4 to 10. Levels of cortisol correlated with higher fasting glucose and increased FFA. FFA in turn correlated with pancreatic β-cell dysfunction.

CONCLUSIONS

Aneurysmal SAH patients have transient abnormalities of glucose metabolism. During the first week, it appears to result predominantly from transient pancreatic β-cell dysfunction, in combination with insulin resistance.

Insulin resistance is unrelated to circulating retinol binding protein and protein C inhibitor

CONTEXT

Recent data suggest that circulating retinol-binding protein (RBP) might be involved in the pathogenesis of insulin resistance. Moreover, protein C inhibitor (PCI), which specifically binds retinoic acid, was found to be increased in myocardial infarction survivors who are also insulin resistant.

OBJECTIVE

The objective of this study was to investigate the association of insulin resistance with RBP factors and PCI active antigen.

DESIGN AND SETTING

This was a clinical study.

PATIENTS

Nondiabetic humans with high (IS; n = 20, 14 females, six males, aged 47.2 +/- 1.9 yr, body mass index 26 +/- 1 kg/m(2)) and low (IR; n = 20, 14 females, six males, aged 45.5 +/- 1.7 yr, body mass index 28 +/- 1 kg/m(2)) insulin-stimulated glucose-disposal (M) participated in this study.

MAIN OUTCOME MEASURES

M was measured by 2-h hyperinsulinemic (40 mU.min(-1).m(-2))-isoglycemic clamp tests. Measurements of RBP were performed using a nephelometric method and validated using quantitative Western blotting.

RESULTS

M (80-120 min) was higher in IS (10.9 +/- 0.6 mg.min(-1).kg(-1)) than IR (4.0 +/- 0.2; P < 10(-12)). Fasting plasma RBP concentrations were comparable between IS and IR measured by both nephelometry (IS: 4.4 +/- 0.3; IR: 4.6 +/- 0.3 mg/dl, P = 0.6) and quantitative Western blot (IS 7.9 +/- 0.5, IR 8.3 +/- 0.6 mg/dl; P = 0.6). Fasting plasma PCI active antigen was similar in both groups. Plasma RBP and PCI were not significantly related to M. RBP was positively correlated with uric acid (r = 0.488, P = 0.003), triglycerides (r = 0.592, P < 0.001), prealbumin (r = 0.63, P < 0.0001), and vitamin A (r = 0.75, P < 10(-6)).

CONCLUSIONS

Our data demonstrate that healthy, insulin-resistant humans do not show altered plasma retinol binding factors, such as RBP and PCI. Both do not significantly correlate with insulin sensitivity. Thus, our findings do not support the hypothesis of insulin sensitivity modulation by proteins involved in retinol transport.