Irina Kowalska

Effects of Prandial Versus Fasting Glycemia on Cardiovascular Outcomes in Type 2 Diabetes: The HEART2D trial

OBJECTIVE—Hyperglycemia and Its Effect After Acute Myocardial Infarction on Cardiovascular Outcomes in Patients With Type 2 Diabetes Mellitus (HEART2D) is a multinational, randomized, controlled trial designed to compare the effects of prandial versus fasting glycemic control on risk for cardiovascular outcomes in patients with type 2 diabetes after acute myocardial infarction (AMI). RESEARCH DESIGN AND METHODS—Patients (type 2 diabetes, aged 30–75 years) were randomly assigned within 21 days after AMI to the 1) prandial strategy (PRANDIAL) (three premeal doses of insulin lispro targeting 2-h postprandial blood glucose <7.5 mmol/l) or the 2) basal strategy (BASAL) (NPH twice daily or insulin glargine once daily targeting fasting/premeal blood glucose <6.7 mmol/l). RESULTS—A total of 1,115 patients were randomly assigned (PRANDIAL n = 557; BASAL n = 558), and the mean patient participation after randomization was 963 days (range 1–1,687 days). The trial was stopped for lack of efficacy. Risks of first combined adjudicated primary cardiovascular events in the PRANDIAL (n = 174, 31.2%) and BASAL (n = 181, 32.4%) groups were similar (hazard ratio 0.98 [95% CI 0.8–1.21]). Mean A1C did not differ between the PRANDIAL and BASAL groups (7.7 ± 0.1 vs. 7.8 ± 0.1%; P = 0.4) during the study. The PRANDIAL group showed a lower daily mean postprandial blood glucose (7.8 vs. 8.6 mmol/l; P < 0.01) and 2-h postprandial blood glucose excursion (0.1 vs. 1.3 mmol/l; P < 0.001) versus the BASAL group. The BASAL group showed lower mean fasting blood glucose (7.0 vs. 8.1 mmol/l; P < 0.001) and similar daily fasting/premeal blood glucose (7.7 vs. 7.3 mmol/l; P = 0.233) versus the PRANDIAL group. CONCLUSIONS—Treating diabetic survivors of AMI with prandial versus basal strategies achieved differences in fasting blood glucose, less-than-expected differences in postprandial blood glucose, similar levels of A1C, and no difference in risk for future cardiovascular event rates.

Insulin resistance, serum adiponectin, and proinflammatory markers in young subjects with the metabolic syndrome

Insulin resistance is the underlying metabolic abnormality in the metabolic syndrome. The low-grade chronic inflammation may be associated with metabolic risk factors and atherogenesis. The aim of our study was to establish the link between the metabolic syndrome, as defined by the National Cholesterol Education Program (NCEP) criteria, and insulin sensitivity, serum adiponectin, and parameters of chronic inflammation in young subjects. The group of 223 subjects (mean age, 25.86 +/- 5.49 years; body mass index, 28.04 +/- 6.91 kg/m2) was studied. Oral glucose tolerance test, euglycemic hyperinsulinemic clamp, and estimation of serum adiponectin and proinflammatory factors were performed. The NCEP-defined metabolic syndrome was present in 49 subjects (21.97%). The higher the number of NCEP criteria fulfilled was, the bigger were the decrease in insulin sensitivity (P < .0001) and adiponectin (P < .0001) and the increase in fasting and postload insulin (both Ps < .0001), C-reactive protein (P < .0001), interleukin 18 (P < .0001), interleukin 6 (P < .0001), and soluble tumor necrosis factor-alpha receptors sTNFR1 (P < .0001) and sTNFR2 (P < .0001) observed. Multiple regression analysis revealed that adiponectin and inflammatory factors predicted NCEP score independent of insulin sensitivity (all adjusted beta values between .16 and .32, all Ps < .01). Young subjects with metabolic syndrome demonstrate an increased inflammatory response and lower adiponectin concentration.

The Effect of Intragastric Balloon on Plasma Ghrelin, Leptin, and Adiponectin Levels in Patients with Morbid Obesity

CONTEXT Ghrelin and leptin are hormones regulating appetite and metabolic processes. Adiponectin plays an important role in the modulation of glucose and lipid metabolism. OBJECTIVE The objective of the study was to evaluate the levels of plasma ghrelin, leptin, and adiponectin in obese subjects treated with bioenterics intragastric balloon (BIB), low-calorie diet (1500 kcal), and physical exercise. DESIGN BIB was placed for 6 months in 21 subjects with body mass index 47.3 +/- 5.7. The control group consisted of 15 morbidly obese subjects treated with a low-calorie diet and physical effort. Plasma hormone levels were determined by RIA. RESULTS In the BIB group, the insertion of the balloon caused a considerable reduction in body mass over a 6-month period (17.1 +/- 8.0 kg) as compared with the control group (3.2 +/- 6.4 kg). After 1 month, the levels of ghrelin increased from 621.9 +/- 182.4 to 903.9 +/- 237 pg/ml and thereafter gradually decreased, reaching the starting level 3 months after the removal of the balloon. In the same group, the levels of leptin decreased from 61.3 +/- 36.7 to 39.9 +/- 17.5 ng/ml. In the control group, the corresponding levels of ghrelin and leptin remained relatively stable. During the observation period, in the BIB group, the levels of adiponectin remained unchanged as opposed to a transient increase noted in the control group. CONCLUSIONS In patients with morbid obesity, weight loss induced by BIB is associated with a decrease in plasma leptin and a transient elevation of plasma ghrelin. It is likely that the changes in hormones regulating the energy balance caused by BIB can prevent an increase in adiponectin level.

Plasma interleukin 8 concentrations in obese subjects with impaired glucose tolerance.

BackgroundInterleukin 8 (IL-8) is a cytokine with atherogenic properties. In vitro studies revealed that it is produced and secreted by human adipocytes. We recently reported that plasma IL-8 is increased in obese subjects with normal glucose tolerance (NGT). The aim of the present study was to measure plasma IL-8 concentrations in subjects with impaired glucose tolerance (IGT).MethodsA total of 44 subjects with marked overweight or obesity (BMI > 27.8 kg/m2), 27 with NGT and 17 with IGT, were recruited for the present study. Plasma IL-8 levels were measured in fasting state, after an oral glucose tolerance test (OGTT) and after euglycemic hyperinsulinemic clamp.ResultsThe studied groups did not differ in fasting IL-8 concentrations. Both OGTT and clamp resulted in a significant increase in plasma IL-8. The change in IL-8 after clamp was similar in both groups. In contrast, after OGTT plasma IL-8 levels (IL-8OGTT) were markedly higher in IGT individuals. In IGT, but not NGT group, IL-8OGTT was positively related to postload glucose and negatively to insulin sensitivity.ConclusionPlasma IL-8 concentrations after glucose load are increased in obese IGT subjects in comparison to normoglycemic weight-matched individuals. Increase in plasma IL-8 might be both insulin-mediated (during clamp) and glucose-mediated (during OGTT).

Serum Retinol Binding Protein 4 Is Related to Insulin Resistance and Nonoxidative Glucose Metabolism in Lean and Obese Women with Normal Glucose Tolerance

CONTEXT Retinol-binding protein (RBP) 4 is secreted by adipose tissue and is postulated to be a determinant of insulin sensitivity. The mechanisms of RBP4 insulin desensitizing action remain unclear. OBJECTIVE The aim of the present study was to estimate the relationships between serum RBP4 concentration with insulin sensitivity and oxidative and nonoxidative glucose metabolism in lean and obese women. DESIGN AND PARTICIPANTS The study group consisted of 67 women with normal glucose tolerance, 27 lean and 40 overweight or obese. Insulin sensitivity was estimated with the euglycemic hyperinsulinemic clamp. Glucose and lipid oxidation was measured with indirect calorimetry in the basal state and during the last 30 min of the clamp. Nonoxidative glucose metabolism was calculated in insulin-stimulated conditions by subtracting glucose oxidation from total glucose metabolism. RESULTS There was no difference in serum RBP4 concentration between lean and obese women. Serum RBP4 was inversely related to insulin sensitivity and nonoxidative glucose metabolism in the entire group (r = -0.36, P =0.003 in both cases) and within the subgroups of lean (r = -0.41, P =0.034 and r = -0.41, P =0.031) and obese women (r = -0.41, P =0.009 and r = -0.40, P =0.01, respectively). These relationships were independent of potential confounding factors. RBP4 levels were not associated with oxidative metabolism of glucose or lipid. CONCLUSIONS Our data indicate that serum RBP4 is related to decreased insulin sensitivity, mostly through its association with nonoxidative glucose metabolism.

Autophagy-regulating TP53INP2 mediates muscle wasting and is repressed in diabetes

A precise balance between protein degradation and synthesis is essential to preserve skeletal muscle mass. Here, we found that TP53INP2, a homolog of the Drosophila melanogaster DOR protein that regulates autophagy in cellular models, has a direct impact on skeletal muscle mass in vivo. Using different transgenic mouse models, we demonstrated that muscle-specific overexpression of Tp53inp2 reduced muscle mass, while deletion of Tp53inp2 resulted in muscle hypertrophy. TP53INP2 activated basal autophagy in skeletal muscle and sustained p62-independent autophagic degradation of ubiquitinated proteins. Animals with muscle-specific overexpression of Tp53inp2 exhibited enhanced muscle wasting in streptozotocin-induced diabetes that was dependent on autophagy; however, TP53INP2 ablation mitigated experimental diabetes-associated muscle loss. The overexpression or absence of TP53INP2 did not affect muscle wasting in response to denervation, a condition in which autophagy is blocked, further indicating that TP53INP2 alters muscle mass by activating autophagy. Moreover, TP53INP2 expression was markedly repressed in muscle from patients with type 2 diabetes and in murine models of diabetes. Our results indicate that TP53INP2 negatively regulates skeletal muscle mass through activation of autophagy. Furthermore, we propose that TP53INP2 repression is part of an adaptive mechanism aimed at preserving muscle mass under conditions in which insulin action is deficient.

Circulating Brain-Derived Neurotrophic Factor Concentration Is Downregulated by Intralipid/Heparin Infusion or High-Fat Meal in Young Healthy Male Subjects

OBJECTIVE Insulin resistance and type 2 diabetes are associated with an increased risk of neurodegenerative diseases. Brain-derived neurotrophic factor (BDNF) regulates neuronal differentiation and synaptic plasticity, and its decreased levels are supposed to play a role in the pathogenesis of Alzheimer’s disease and other disorders. The aim of the current study was to estimate the effects of hyperinsulinemia and serum free fatty acids (FFA) elevation on circulating BDNF concentration in humans. RESEARCH DESIGN AND METHODS We studied 18 healthy male subjects (mean age 25.6 ± 3.0 years; mean BMI 26.6 ± 4.8 kg/m2). Serum and plasma BDNF concentration was measured in the baseline state and in the 120 and 360 min of euglycemic hyperinsulinemic clamp with or without intralipid/heparin infusion. Furthermore, plasma BDNF was measured in 20 male subjects (mean age 22.7 ± 2.3 years; mean BMI 24.9 ± 1.5 kg/m2) 360 min after a high-fat meal. RESULTS Insulin sensitivity was reduced by ∼40% after 6 h of intralipid/heparin infusion (P < 0.001). During both clamps, serum and plasma BDNF followed the same pattern. Hyperinsulinemia had no effect on circulating BDNF. Raising FFA had no effect on circulating BDNF in 120 min; however, it resulted in a significant decrease by 43% in serum and by 35% in plasma BDNF after 360 min (P = 0.005 and 0.006, respectively). High-fat meal also resulted in a decrease by 27.8% in plasma BDNF (P = 0.04). CONCLUSIONS Our data show that raising FFA decreases circulating BDNF. This might indicate a potential link between FFA-induced insulin resistance and neurodegenerative disorders.

Increased suppression of serum ghrelin concentration by hyperinsulinemia in women with anorexia nervosa

CONTEXT Ghrelin is a peptide secreted mainly by the stomach, which has the ability to stimulate appetite and food intake. Serum ghrelin concentration decreases rapidly after a meal, probably because of the concurrent increase in serum insulin. Anorexia nervosa (AN) is an eating disorder, which is characterized by high serum ghrelin concentration; however, the regulation of circulating ghrelin by insulin in this disorder remains unclear. OBJECTIVE To estimate serum ghrelin concentration in the fasting state and after hyperinsulinemia in women with AN. DESIGN AND PARTICIPANTS We examined 19 women with AN, 26 lean healthy women, and 25 women who were overweight or obese. Serum ghrelin concentration was measured in the fasting state and after euglycemic hyperinsulinemic clamp. RESULTS Insulin sensitivity was similar in AN and normal-weight women, and was markedly decreased in the obese subjects. In the fasting state, serum ghrelin was higher in AN group than in other groups (normal-weight, P=0.017; obese, P=0.0001) and in normal-weight women than in obese women (P=0.044). Hyperinsulinemia resulted in a marked decrease in serum ghrelin in AN (P<0.0001) and normal-weight women (P=0.002). The fall in serum ghrelin was higher in AN group than in other groups (normal-weight, P=0.0008; obese, P=0.0001), and was related to insulin sensitivity (r=0.24, P<0.05). In multiple regression analysis, only fasting serum ghrelin and the presence of AN were independent predictors of this fall. CONCLUSIONS Women with AN have an increased suppression of serum ghrelin by hyperinsulinemia. This phenomenon might lead to an increased and more rapid feeling of satiety in AN.

The Role of Skeletal Muscle Sphingolipids in the Development of Insulin Resistance

Insulin resistance is an important risk factor for type 2 diabetes, obesity, cardiovascular disease, polycystic ovary syndrome and other diseases. The most important stage in the development of insulin resistance is impairment of insulin-stimulated skeletal muscle glucose uptake. There is evidence that intramyocellular lipids might be responsible for this process through inhibition of insulin signaling. One of the important intracellular lipid pools is associated with the sphingomyelin signaling pathway. The second messenger in this pathway is ceramide. In vitro data indicate that ceramide inhibits insulin signaling, mainly through inactivation of protein kinase B. In vivo data suggest that ceramide accumulation within muscle cells might be associated with the development of insulin resistance. In this review, we discuss both in vitro and in vivo evidence for the role of muscle ceramide in the impairment of insulin action with particular focus on the question whether findings from animal studies are applicable to humans. We describe problems that are unresolved so far and topics of potential interest for future research.

Increased serum interleukin-18 concentration is associated with hypoadiponectinemia in obesity, independently of insulin resistance.

Objective:Interleukin-18 (IL-18) is a cytokine with proinflammatory and proatherogenic properties, which might be associated with the development of insulin resistance. In contrast, adiponectin, a protein secreted by adipose tissue, might exert insulin-sensitizing and antiatherogenic effects. The aim of the present study was to analyze the association between serum IL-18 and adiponectin in lean and obese subjects, in relation to insulin resistance.Design:Cross-sectional study.Subjects:One hundred and thirty individuals, 62 lean (body mass index (BMI)<25 kg/m2, 30 men and 32 women) and 68 with overweight or obesity (BMI>25 kg/m2, 24 men and 44 women), with normal glucose tolerance and without concomitant diseases.Measurements:Oral glucose tolerance test, euglycemic hyperinsulinemic clamp, serum concentrations of IL-18, IL-6, soluble tumor necrosis factor-α receptors and adiponectin.Results:Obese subjects had lower insulin sensitivity (M value, P=0.00029) and serum adiponectin (P=0.01) and higher levels of serum IL-18 (P=0.00055). Circulating IL-18 was negatively related to adiponectin (r=−0.31, P=0.00027) and insulin sensitivity (r=−0.33, P=0.00012). Subgroup analysis revealed that these associations were present in the obese (adiponectin, r=−0.38, P=0.0014; M, r=−0.29, P=0.016), but not in lean individuals (r=−0.17, P=0.18 and r=−0.20, P=0.12, respectively). Association of IL-18 with adiponectin remained significant after adjustment for other estimated parameters, including insulin sensitivity. Also, relationship between IL-18 and insulin sensitivity was independent of other estimated parameters.Conclusion:Serum IL-18 is inversely related to serum adiponectin, independently of insulin resistance. The relationships of IL-18 with adiponectin and insulin sensitivity are influenced by the presence of overweight/obesity.