Metabolic response to oral lipid overload in diabetes and impaired glucose tolerance

Fasted exercise does not improve postprandial lipemia responses to different meals in lean and obese subjects: A crossover, randomized clinical trial

INTRODUCTION

Persistent episodes of postprandial hyperlipemia (PPL) and hyperglycemia (PPG) are considered risk factors for coronary heart disease (CHD) and premature death; whereas physical exercise improves lipid profile and glucose tolerance thus decreasing cardiovascular risks.

OBJECTIVE

To investigate the effects of low-intensity fasted aerobic exercise on the magnitude of the PPL and PPG responses to meals with different energy content, in normal and obese subjects.

METHODS

The study used a randomized crossover design. Twenty-one male (Lean: n = 9, BMI: 24.3 ± 2.2; and obese: n = 12, BMI 32.31 ± 2.1) volunteers aged 20-30 years, performed three interventions, separated by 7 days each: (i) 45 min at rest and isocaloric high-fat meal (60% lipids, 30% carbohydrates and 10% protein); (ii) fasted low-intensity aerobic exercise (50% VO_2max) for 45 min followed by an isocaloric or (iii) calorie deficit high-fat meal. Subjects were serially assessed for blood triglycerides, and glucose levels.

RESULTS AND CONCLUSIONS

Low-intensity fasted aerobic exercise had no acute effect on PPL in lean and obese subjects. Glucose concentrations were reduced only in lean subjects. There is a significant difference in PPL values when comparing lean to obese subjects, implying that the nutritional status influences lipid and carbohydrate after fasted low-intensity aerobic exercise. Registered under ClinicalTrials.gov Identifier no. NCT00929890.

Effects of a liquid high-fat meal on postprandial lipid metabolism in type 2 diabetic patients with abdominal obesity

Background

Postprandial lipemia and lipoprotein lipase (LPL) activity play crucial roles in the pathogenesis of accelerated atherosclerosis. This study aimed to evaluate the postprandial lipid metabolism after the ingestion of a liquid high-fat meal in type 2 diabetic patients with abdominal obesity, and determine if the PvuII polymorphisms of LPL influence their postprandial lipid responses.

Methods

Serum glucose, insulin, triglycerides (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were measured in fasting and postprandial state at 0.5, 1, 2, 4, 6 and 8 h after a liquid high-fat meal in 51 type 2 diabetic patients with abdominal obesity, 31 type 2 diabetic patients without abdominal obesity and 39 controls. Their PvuII polymorphisms of LPL were tested in fasting.

Results

Type 2 diabetic patients with abdominal obesity had significantly higher postprandial areas under the curve (AUC) of glucose [least square mean difference (LSMD) = 30.763, 95% confidence interval (CI) = 23.071–38.455, F = 37.346, P < 0.05] and TC (LSMD = 3.995, 95% CI = 1.043–6.947, F = 3.681, P < 0.05) than controls. Postprandial AUCs for insulin, homeostasis model assessment-insulin resistance (HOMA-IR) and TG were higher (LSMD = 86.987, 95% CI = 37.421–136.553, F = 16.739, P < 0.05; LSMD = 37.456, 95% CI = 16.312–58.600, F = 27.012, P < 0.05; LSMD = 4.684, 95% CI = 2.662–6.705, F = 26.158, P < 0.05), whereas HDL-C AUC was lower (LSMD = −1.652, 95% CI = −2.685 – -0.620, F = 8.190, P < 0.05) in type 2 diabetic subjects with abdominal obesity than those without abdominal obesity. In type 2 diabetic patients with abdominal obesity, postprandial TG AUC was lower in P−/− than in P+/− (LSMD = −4.393, 95% CI = −9.278 – -0.491, F = 4.476, P < 0.05) and P+/+ (LSMD = −7.180, 95% CI = −12.319 – -2.014, F = 4.476, P < 0.05) phenotypes. Postprandial AUCs for glucose, insulin, HOMA-IR, TC and HDL-C were not different according to PvuII phenotypes.

Conclusions

Abdominal obesity exacerbates the postprandial lipid responses in type 2 diabetic patients, which partly explains the excess atherogenic risk in these patients. In addition, the presence of P+ allele could contribute to a greater postprandial TG increase in type 2 diabetic patients with abdominal obesity.

Trial registration

ChiCTR-IOR-16008435. Registered 8 May 2016.

Divergent phenotypes in siblings with identical novel mutations in the HNF-1α gene leading to maturity onset diabetes of the young type 3

BACKGROUND

Maturity onset diabetes of the young (MODY) is an autosomal dominant form of non-insulin-dependent diabetes mellitus caused by mutations in at least 13 different genes. The hepatocyte nuclear factor (HNF)-1α gene is affected in the most common form (HNF1A-MODY [MODY3]).

CASE PRESENTATION

We describe the co-inheritance of a novel heterozygous missense mutation c.1761C > G (p.Pro588Ala) with a novel complex deletion insertion mutation (c.1765_1766delinsGCCCGfs86*) in the HNF-1α gene among affected members of one family. Both mutations were present in the affected patients and neither was present in unaffected family members. The family had not only inheritance of MODY but also increased susceptibility to type 2 diabetes. Therefore one family member had classical type 2 diabetes including metabolic syndrome aggravated by a genetic predisposition in the form of HNF1A-MODY.

CONCLUSION

The presence of common type 2 diabetes features should not detract from the possibility of MODY in patients with a striking autosomal-dominant family history.

Postprandial metabolism and inflammatory markers in overweight adolescents

Lifestyle changes have an impact on lipid metabolism. The overload of circulating lipids may lead to endothelial dysfunction, oxidative stress and exaggerated inflammatory response, which may be further aggravated in the presence of overweight. This study aims to describe the postprandial metabolism and inflammatory response in overweight and normal-weight adolescents. Sixty-two adolescents aged 11–18 years were divided into two groups: overweight (OW; n=38) and normal weight (NW; n=24). Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), fibrinogen and leukocytes were collected for fasting and 4 and 6 h after a oral fat tolerance test (OFTT) consisting of a high-fat meal with 1.000 Kcal, 27.4% carbohydrates, 14.7% protein and 57.8% lipids (30.4% saturated, 32.7% monounsaturated, 26.5% polyunsaturated fatty acids and 288 mg TC). Data were analyzed with repeated measures ANOVA, multiple linear regression, and Pearson, Spearman and partial correlations. OW adolescents showed significantly higher fasting values of TC (P=0.036), LDL-C (P=0.010), fibrinogen (P=0.036) and hs-CRP (P=0.004). All variables, except for glucose, increased in response to OFTT, but there were no interactions between group and time. body mass index z-score was positively correlated to LDL-C, TG, fibrinogen and hs-CRP, and inversely correlated to HDL-C. In conclusion, adolescents with OW showed higher TC, LDL-C and inflammatory markers levels than NW adolescents. These findings have clinical implications for prevention of chronic diseases, as we spend most of our days in a postprandial state.

Activation of FFA1 mediates GLP-1 secretion in mice. Evidence for allosterism at FFA1

FFA1 (GPR40) and GPR120 are G-protein-coupled receptors activated by long-chain fatty acids. FFA1 is expressed in pancreatic β-cells, where it regulates glucose-dependent insulin secretion, and GPR120 has been implicated in mediating GLP-1 secretion. We show here that FFA1 co-localizes with GLP-1 in enteroendocrine cells and plays a critical role in glucose management by mediating GLP-1 secretion in vivo. Corn oil induces GLP-1 secretion in wild type mice and in GPR120-/- mice, but not in FFA1-/- mice. α-Linolenic acid, an endogenous ligand of FFA1, induces GLP-1 secretion in GLUTag cells and in primary fetal mouse intestinal cells. Synthetic partial FFA1 agonists do not stimulate GLP-1 secretion in mice, but partial and full agonists combined function cooperatively to enhance receptor activation and GLP-1 secretion both in vitro and in vivo. We conclude that allosterism at FFA1 can contribute to postprandial glucose management by stimulating insulin secretion via an extrapancreatic mechanism of action, and that GPR120 in GLP-1 secretion requires further investigation.

The influence of weight excess on the postprandial lipemia in adolescents

BACKGROUND

Postprandial lipemia (PL) in adults has been extensively studied, but little explored in youth. The aim of this study was to evaluate the influence of weight excess on postprandial lipemia in adolescents.

METHODS

Eighty-three adolescents were classified into Groups 1 (n= 49, overweight) and 2 (n=34, eutrophic). Total cholesterol (TC), triglycerides (TG), HDL and LDL cholesterol were measured before, 2 and 4 hours after a standardized 25 g lipid and 25 g of carbohydrate test meal; glycemia and insulin measured only at baseline. Anthropometric evaluation was performed.

RESULTS

Basal TG were higher in Group 1 (p= 0.022). The total increase (Δ-TG), corresponding to the difference between the maximum and the basal TG level was similar in both groups (29.8 ± 21.5 mg/dl vs. 28.2 ± 24.5 mg/dl, p= 0.762). TC, HDL and LDL did not change significantly throughout the test. By analyzing all the adolescents together, the waist circumference was positively correlated with TG at fasting (r = 0.223; p= 0.044) and at 4 hours (r = 0.261; p= 0.019). Only overweight adolescents with hypertriglyceridemia, who also had higher HOMA-IR, presented significant elevation of TG levels 2 and 4 hours after the overload.

CONCLUSION

The behavior of lipoproteins in the post-prandial state is similar in eutrophic and overweight adolescents. Thus, apparently the weight excess does not induce post prandial lipemic alterations.

[The role of post-prandial lipids in atherogenesis: particularities of diabetes mellitus]

Atherosclerosis is a complex and multifactorial disease, which determines clinical events that cause significant morbidity-mortality, represented by acute myocardial infarction, angina and sudden death. It is associated with lipid disturbances, platelet activation, thrombosis, endothelial dysfunction, inflammation, oxidative stress, altered matrix metabolism, among other disturbances. All these abnormalities are usual and more pronounced in diabetic patients, as well as in the post-prandial state. Among the coronary artery disease risk factors that are not usually employed in clinical practice in the whole population, postprandial hyperlipemia plays a major role, being a possible early marker of metabolic abnormalities and vascular dysfunction not yet seen in the fasting state. Recent results showed that post-oral lipid overload changes are negatively associated with endothelial dysfunction, and vascular reactivity abnormalities are strongly related to atherosclerosis progression and cardiovascular events. These abnormalities could disclose a lipid intolerance state that can be detected in apparently healthy subjects even before fasting abnormalities are seen. This review will deal with the pathophysiology changes involved in post-prandial hyperlipemia and its relationship with atherogenesis, with particular emphasis to diabetes mellitus.

Postprandial lipaemia in patients with impaired fasting glucose, impaired glucose tolerance and diabetes mellitus

AIMS

To compare the postprandial lipid responses in subjects with prediabetes (IFG and IGT), newly detected diabetes mellitus (NDDM) and normal glucose tolerance (NGT).

METHODS

Postprandial lipid responses to a standard oral fat challenge was studied in forty-four subjects who were divided after an OGTT into NGT, pure impaired fasting glucose (PIFG), pure impaired glucose tolerance (PIGT) and NDDM.

RESULTS

There was a significantly higher postprandial triglyceride (PPTg) response with a higher PPTg area under curve (p=0.004) and peak PPTg levels (p=0.003) in patients with NDDM but not with either PIFG (p>0.05) or PIGT (p>0.05) when compared with NGT. Overall, PPTg responses correlated significantly with fasting plasma glucose (p=0.001) and 2h plasma glucose (p=0.001) but not with age, sex, body mass index, waist, or insulin resistance.

CONCLUSION

Subjects with newly detected diabetes mellitus displayed postprandial hypertriglyceridemia after a standard oral fat meal challenge while no such abnormality could be demonstrated in subjects with IFG or IGT. This defect is probably related to glycemic status and insulin resistance.

Reduced venous endothelial responsiveness after oral lipid overload in healthy volunteers

The aim of this study was to investigate endothelial venous function, inflammatory markers, and systemic oxidative stress after an oral lipid overload (OLO). We studied 18 healthy adults (9 men; age, 29.2 +/- 0.9 years; body mass index, 22.3 +/- 0.4 kg/m(2)). Blood samples were collected in the fasting state and 3, 4, and 5 hour after the OLO (1000 kcal, 58% fat) for metabolic variables, oxidative stress, inflammatory markers, adiponectin, and resistin. Changes in vein diameter to phenylephrine, acetylcholine, and sodium nitroprusside (dorsal hand vein technique) were measured before and after the OLO. Oral lipid overload increased triglycerides (61 +/- 6 vs 134 +/- 17 mg/dL, P < .001), insulin (7.2 +/- 0.8 vs 10.7 +/- 1.3 muU/mL, P < .05), and resistin (5.38 +/- 0.5 vs 6.81 +/- 0.7 ng/mL, P < .05) and reduced antioxidant capacity (plasma total antioxidant capacity: 186.7 +/- 56 vs 161.8 +/- 50 U Trolox per microliter plasma, P < .01), vascular reactivity (171.3 +/- 85 vs 894.4 +/- 301 ng/mL, P < .001), and maximum acetylcholine venodilation (105.9% +/- 9% vs 61.0% +/- 7%, P < .05). No changes were observed for sodium nitroprusside. Post-OLO triglycerides were positively correlated with phenylephrine dose (rho = 0.38, P < .05) and resistin (rho = 0.43, P < .01) and negatively correlated with the maximum acetylcholine venodilation (rho = -0.36, P < .05). In conclusion, an OLO impaired venoconstriction responsiveness in healthy subjects, probably because of a reduction in the antioxidant capacity.

Emerging risk factors and early atherosclerosis indices in subjects with impaired glucose tolerance

AIM

To evaluate the response to an oral lipid overload, inflammatory markers and carotid intima-media thickness in subjects with impaired glucose tolerance.

METHODS

54 subjects, both sexes, 58 y-old average were submitted to 1) Clinical evaluation 2) Glucose tolerance test with 75 g glucose; classified as normal (2 h plasma glucose<140 mg/dl, n=37) or IGT (2 h G 140-200 mg/dl, n=17), 3) 12 h fasting sample (plasma glucose, lipids, C-reactive protein, fibrinogen and HOMA-IR calculation); 4 and 6 h after the oral lipid overload (1000 kcal, lipids 65 g) glycemia, fibrinogen and triglycerides were reevaluated. Intima-media thickness was calculated by the average of 6 measurements (3 highest of each carotid) evaluated by ultrasonography (7 MHZ transducer).

RESULTS

The IGT group had higher (P<0.001) fasting plasma glucose (89.4 +/- 13 vs 104.4 +/- 8 mg/dl), HOMA-IR (1.69 +/- 1.2 vs 2.93 +/- 2.2) and waist (91 +/- 14 vs 101 +/- 9 cm), similar fasting lipids, intima-media thickness (P=0.58) and post-oral lipid overload triglycerides (P=0.74), but higher fibrinogen (284.3 +/- 6 and 305 +/- 10 mg/dl, P=0.05) and C-reactive protein (2.11 +/- 0.33 and 4.19 +/- 0.65 mg/l, P=0.003). C-reactive protein was positively correlated with HOMA-IR (r=0.45, P=0.001), fasting plasma glucose (r=0.43, P=0.002) and waist (r=0.45, P=0.0006), but not with postprandial lipids.

CONCLUSION

A higher C-reactive protein in IGT, and its positive correlation with insulin resistance indices, but not with postprandial lipaemia, suggests that the clustering of these factors, characteristic of the metabolic syndrome, occurs earlier than postprandial lipid abnormalities.