Impaired endothelial function and insulin action in first-degree relatives of patients with type 2 diabetes mellitus

Cocoa Flavanol Supplementation and the Effect on Insulin Resistance in Females Who Are Overweight or Obese: A Randomized, Placebo-Controlled Trial

There is interest in the impact that dietary interventions can have on preventing the transition from insulin resistance to type 2 diabetes, including a suggestion that the bioactive components of cocoa may enhance fasting insulin sensitivity. However, a role for cocoa flavanols (CF) in reducing insulin resistance in the insulin-stimulated state, an important risk factor for cardiovascular disease, is unresolved. This study investigated whether CF consumption improved whole-body insulin-mediated glucose uptake ('M') in females with overweight/obesity, using a randomized, double-blinded, placebo-controlled, parallel-group design. Thirty-two premenopausal females (19-49 years; 27-35 kg·m^-2) with elevated HOMA-IR (HOMA-IR >1.5) supplemented their habitual diet with two servings/day of a high-flavanol cocoa drink (HFC; 609 mg CF/serving; n = 16) or low-flavanol cocoa drink (LFC; 13 mg CF/serving; n = 16) for 4 weeks. Assessment of HOMA-IR and 'M' during a 3-h, 60 mIU insulin·m^-2·min^-1 euglycemic clamp was performed before and after the intervention. Data are the mean (SD). Changes to HOMA-IR (HFC -0.003 (0.57); LFC -0.0402 (0.86)) and 'M' (HFC 0.99 (7.62); LFC -1.32 (4.88) µmol·kg^-1·min^-1) after the intervention were not different between groups. Four weeks' consumption of ~1.2 g CF/day did not improve indices of fasting insulin sensitivity or insulin-mediated glucose uptake. A recommendation for dietary supplementation with cocoa flavanols to improve glycemic control is therefore not established.

Impaired postprandial skeletal muscle vascular responses to a mixed meal challenge in normoglycaemic people with a parent with type 2 diabetes

AIMS/HYPOTHESIS

Microvascular blood flow (MBF) increases in skeletal muscle postprandially to aid in glucose delivery and uptake in muscle. This vascular action is impaired in individuals who are obese or have type 2 diabetes. Whether MBF is impaired in normoglycaemic people at risk of type 2 diabetes is unknown. We aimed to determine whether apparently healthy people at risk of type 2 diabetes display impaired skeletal muscle microvascular responses to a mixed-nutrient meal.

METHODS

In this cross-sectional study, participants with no family history of type 2 diabetes (FH-) for two generations (n = 18), participants with a positive family history of type 2 diabetes (FH+; i.e. a parent with type 2 diabetes; n = 16) and those with type 2 diabetes (n = 12) underwent a mixed meal challenge (MMC). Metabolic responses (blood glucose, plasma insulin and indirect calorimetry) were measured before and during the MMC. Skeletal muscle large artery haemodynamics (2D and Doppler ultrasound, and Mobil-O-graph) and microvascular responses (contrast-enhanced ultrasound) were measured at baseline and 1 h post MMC.

RESULTS

Despite normal blood glucose concentrations, FH+ individuals displayed impaired metabolic flexibility (reduced ability to switch from fat to carbohydrate oxidation vs FH-; p < 0.05) during the MMC. The MMC increased forearm muscle microvascular blood volume in both the FH- (1.3-fold, p < 0.01) and FH+ (1.3-fold, p < 0.05) groups but not in participants with type 2 diabetes. However, the MMC increased MBF (1.9-fold, p < 0.01), brachial artery diameter (1.1-fold, p < 0.01) and brachial artery blood flow (1.7-fold, p < 0.001) and reduced vascular resistance (0.7-fold, p < 0.001) only in FH- participants, with these changes being absent in FH+ and type 2 diabetes. Participants with type 2 diabetes displayed significantly higher vascular stiffness (p < 0.001) compared with those in the FH- and FH+ groups; however, vascular stiffness did not change during the MMC in any participant group.

CONCLUSIONS/INTERPRETATION

Normoglycaemic FH+ participants display impaired postprandial skeletal muscle macro- and microvascular responses, suggesting that poor vascular responses to a meal may contribute to their increased risk of type 2 diabetes. We conclude that vascular insulin resistance may be an early precursor to type 2 diabetes in humans, which can be revealed using an MMC.

The Association Between Arterial Stiffness and Muscle Indices Among Healthy Subjects and Subjects With Cardiovascular Risk Factors: An Evidence-Based Review

Skeletal muscle is one of the major tissues in the body and is important for performing daily physical activity. Previous studies suggest that vascular dysfunction contributes to reduced skeletal muscle mass. However, the association between vascular dysfunction and muscle mass, muscle strength and muscle flexibility are less established. Therefore, the focus of this review was to investigate the association between arterial stiffness (AS) which is a marker of vascular function, and muscle indices among healthy and those with cardiovascular risk factors. Three databases were used to search for relevant studies. These keywords were used: "arterial stiffness" OR "vascular stiffness" OR "aortic stiffness" OR "pulse wave velocity" OR "carotid femoral pulse wave velocity" OR "pulse wave analysis" AND "muscle" OR "skeletal" OR "flexibility" OR "range of motion" OR "articular" OR "arthrometry" OR "strength" OR "hand strength" OR "pinch strength" OR "mass" OR "lean" OR "body composition." The criteria were; (1) original, full-text articles, (2) articles written in English language, (3) human studies involving healthy adults and/or adults with cardiovascular disease (CVD) or CVD risk factors (4) articles that reported the relationship between AS (measured as carotid-femoral pulse wave velocity or brachial-ankle pulse wave velocity) and muscle indices (measured as muscle mass, muscle flexibility and muscle strength) after adjusting for relevant confounders. The search identified 2295 articles published between 1971 and June 2021. Only 17 articles fulfilled the criteria. Two studies showed an inverse association between AS and muscle strength in healthy subjects, whereas in subjects with CVD risk factors, five out of seven studies found an inverse correlation between the two parameters. Eleven studies showed an inverse association between AS and muscle mass in subjects with CVD and CVD risk factors. The association between AS and muscle flexibility was not studied in any of the articles reviewed. In conclusion, there is an inverse correlation between muscle indices and AS in healthy adults and those with CVD or CVD risk factors. However, most of the studies were cross-sectional studies, hence the need for future prospective studies to address this issue.

Association of Lipid Profile with Type 2 Diabetes in First-Degree Relatives: A 14-Year Follow-Up Study in Iran

PURPOSE

Dyslipidemia is claimed to be associated with an increased risk of type 2 diabetes mellitus (T2DM). However, first-degree relatives (FDRs) of patients with T2DM are reported to be at higher risk. The aim of this study was to evaluate the association between serum lipid profile and T2DM incidence in FDRs.

PATIENTS AND METHODS

Information on 1222 T2DM FDRs during 14 years of follow-up was retrieved. All individuals were examined for diabetes status and dyslipidemia once a year. We used a Bayesian joint longitudinal-survival model to assess the association.

RESULTS

Our data showed that a 10 mg/dL increase in triglycerides (TG), very-low-density lipoprotein (VLDL), and non-high-density lipoprotein (non-HDL) cholesterol levels during the follow-up period was associated with an increased risk of diabetes by 5%, 29%, and 6.6%, respectively. Moreover, for every one-unit increase in the TG to HDL ratio, the T2DM incidence increased by 35%. Subgroup analysis also showed that the increased risk of diabetes was significant only in female FDRs, so that a 10 mg/dL increase in TG and VLDL cholesterol level and a one-unit increase in TG to HDL ratio in female FDRs resulted in an increased risk of diabetes by 7.8%, 46%, and 64%, respectively. However, analysis of HDL, low-density lipoprotein (LDL), total cholesterol (TC), TC to HDL, and LDL to HDL cholesterol levels/ratios did not find any statistically significant associations.

CONCLUSION

Increases in TG, VLDL, non-HDL cholesterol level, and TG to HDL ratio are associated with an increased risk of T2DM in FDRs, especially in female FDRs.

Impaired endothelial function in siblings of patients with diabetic mellitus type 2

Background

Endothelial dysfunction is considered as a risk factor for cardiovascular disease, which is a consistent finding in diabetic mellitus type 2 (DMT2). First-degree relatives of DMT2 patients have a higher risk of developing DMT2 later on the life. We aimed to investigate whether impaired endothelial function exists in siblings of DMT2 patients.

Methods

As endothelial function markers, plasma E-selectin, soluble inter-cellular adhesion molecule-1 (sICAM-1), and endothelin-1 (ET-1) were measured on 27 DMT2 patients (9 m/18f; mean age: 48.48 ± 6.75 years), 28 siblings of DMT2 patients (14 m/14f; mean age: 44.54 ± 7.10 years), and 30 control subjects (18 m/12f; mean age: 44.72± 7.56 years) without any family history of diabetes. All the groups were matched by gender, age, and body mass index (BMI).

Results

Plasma levels of ET-1, sICAM-1, and E-selectin were significantly higher in the DMT2 group compared to the control group (ET-1:0.79 ± 1.63 pg/ml vs. 0.33 ± 0.08 pg/ml; P_CD = 0.049, sICAM-1: 71.15 ± 27.20 ng/ml vs. 34.57 ± 22.56 ng/ml; P_CD = 0.001, E-selectin: 22.45 ± 11.57 ng/ml vs. 16.28 ± 7.50 ng/ml; P_CD =0.026). There was a significant difference in sICAM-1 levels between siblings (62.08 ± 26.37 ng/ml) and controls (P_CS = 0.002), but not between siblings and DMT2 patients (P_SD = 0.411). Moreover, a significant difference was observed in ET-1 levels between siblings (0.75 ± 1.26 pg/ml) and controls (P_CS = 0.031), but not between siblings and DMT2 patients (P_SD = 0.751). There was also a significant difference in E-selectin levels between DMT2 patients and siblings (16.56 ± 8.71 ng/ml; P_SD =0.028); however, the difference in E-selectin levels was not statistically significant between siblings and controls (P_CS = 0.919).

Conclusion

Endothelial function markers in the siblings of DMT2 patients are increased in comparision to the control group Therefore; family history in the DMT2 patients seems to be a risk factor for endothelial function. Furthermore, endothelial dysfunction is available very early in the DMT2 patients, even before overt hyperglycemia ensues (in siblings), and may play a key role in the etiopathology of the vasculopathy associated with DMT2.

Training Does Not Alter Muscle Ceramide and Diacylglycerol in Offsprings of Type 2 Diabetic Patients Despite Improved Insulin Sensitivity

Ceramide and diacylglycerol (DAG) may be involved in the early phase of insulin resistance but data are inconsistent in man. We evaluated if an increase in insulin sensitivity after endurance training was accompanied by changes in these lipids in skeletal muscle. Nineteen first-degree type 2 diabetes Offsprings (Offsprings) (age: 33.1 ± 1.4 yrs; BMI: 26.4 ± 0.4 kg/m²) and sixteen matched Controls (age: 31.3 ± 1.5 yrs; BMI: 25.3 ± 0.7 kg/m²) performed 10 weeks of endurance training three times a week at 70% of VO₂max on a bicycle ergometer. Before and after the intervention a hyperinsulinemic-euglycemic clamp and VO₂max test were performed and muscle biopsies obtained. Insulin sensitivity was significantly lower in Offsprings compared to control subjects (p < 0.01) but improved in both groups after 10 weeks of endurance training (Off: 17 ± 6%; Con: 12 ± 9%, p < 0.01). The content of muscle ceramide, DAG, and their subspecies were similar between groups and did not change in response to the endurance training except for an overall reduction in C22:0-Cer (p < 0.05). Finally, the intervention induced an increase in AKT protein expression (Off: 27 ± 11%; Con: 20 ± 24%, p < 0.05). This study showed no relation between insulin sensitivity and ceramide or DAG content suggesting that ceramide and DAG are not major players in the early phase of insulin resistance in human muscle.

Relationship between islet function and bone mineral density in first-degree relatives of patients with type 2 diabetes

AIM: To explore the relationship between islet function and bone mineral density in first-degree relatives of type 2 diabetes mellitus (T2DM) patients.

METHODS: In first-degree relatives of T2DM patients, 30 cases with normal glucose tolerance (NGT) [NGT (+) group] and 30 cases with impaired glucose tolerance (IGT) [IGT (+) group] were included in the study. Thirty healthy controls without family history of T2DM [NGT (-) group] were also included. Electrochemical luminescence immunoassay was used to test fasting insulin level and insulin level at 2 h after oral administration of 75 g anhydrous glucose powder. Lumbar spine and left femur bone mineral density was determined by X-ray absorptiometry.

RESULTS: The homeostasis model assessment-pancreatic beta-cell function (HOMA-beta) was significantly lower in the NGT (-) group than in the NGT (+) group and IGT (+) group, but showed no statistical difference between the NGT (+) group and IGT (+) group. Compared with the IGT (+) group and NGT (+) group, bone density of L2 to L4 (L2-L4), the femoral neck and femoral trochanter was significantly different in the NGT (-) group, although there was no statistical difference between NGT (+) group and NGT (-) group.

CONCLUSION: All T2DM first-degree relatives, regardless of whether they have NGT or IGT, have decreased islet function, and T2DM first-degree relatives with IGT have decreased bone mineral density in the lumbar spine and femoral both.

Insulin resistance and acute glucose changes determine arterial elastic properties and coronary flow reserve in dysglycaemic and first-degree relatives of diabetic patients

BACKGROUND

Insulin resistance is linked to endothelial dysfunction. We investigated whether first-degree relatives of type-2 diabetes patients (FDR) present differences in vascular function at baseline and during postprandial hyperglycemia compared to dysglycaemic or normoglycaemic subjects.

METHODS

We studied 40 FDR with normal oral glucose test (OGTT), 40 subjects with abnormal OGTT (dysglycaemic) and 20 subjects with normal OGTT without parental history of diabetes (normoglycaemic) with similar clinical characteristics. Glucose, insulin, pulse wave velocity (PWV), central systolic blood pressure (cSBP) and augmentation index (AI) were measured at 0, 30, 60, 90 and 120min during OGTT. Coronary flow reserve (CFR) was assessed using Doppler echocardiography at 0 and 120min after OGTT. Insulin sensitivity was evaluated using Matsuda and insulin sensitivity index (ISI).

RESULTS

FDR and dysglycaemics had higher fasting insulin, reduced ISI, Matsuda index as well as reduced CFR (2.54 ± 0.5 vs. 2.45 ± 0.3 vs. 2.74 ± 0.5), increased PWV, (8.9 ± 1.1 vs. 10.3 ± 2.4vs. 8.0 ± 1.5 m/sec), AI (23.8 ± 13.6 vs. 26.5 ± 14.4vs.17.7  ±  14%) and cSBP than normoglycaemics (p < 0.05 for all comparisons). During OGTT, AI was similarly reduced in both normoglycaemic and FDR (p < 0.05) at peak insulin levels (60 min) though FDR had 2-fold higher insulin than normoglycaemics. AI was increased in dysglycaemics after peak glucose levels, at 120 min (p < 0.05). CFR was reduced by 10% and 15% at 120min in FDR and dysglycaemic respectively, while remained unchanged in normoglycaemics (p < 0.05). The percent reduction of CFR was related with the percent increase of glucose levels, ISI and Matsuda index(p < 0.05).

CONCLUSION

First-degree relatives and dysglycaemic patients have impaired arterial and coronary microcirculatory function. Insulin resistance determines acute vascular responses during postprandial hyperglycemia. CLINICALTRIALS.

GOV IDENTIFIER

NCT02244736.

Increases in muscle blood flow after a mixed meal are impaired at all stages of type 2 diabetes

OBJECTIVE

In type 2 diabetes, although the impairment of postprandial muscle blood flow response is well established, information on the effect of this impairment on glucose uptake and lipid metabolism is controversial.

DESIGN

Postprandial forearm blood flow responses and metabolic parameters were assessed in a cross-sectional study of subjects at various stages of insulin resistance.

PATIENTS

Eleven healthy subjects (CONTROLS), 11 first-degree relatives of type-2 diabetics (RELATIVES), 10 patients with impaired glucose tolerance (IGT), 10 diabetic patients with postprandial hyperglycaemia (DMA), and 13 diabetic patients with both fasting and postprandial hyperglycaemia (DMB).

MEASUREMENTS

All subjects received a meal. Blood was drawn from a forearm deep vein and the radial artery at specific time-points during a period of 360 min for measurements of glucose, insulin, triglycerides and nonesterified-fatty acids. Forearm muscle blood flow was measured with strain-gauge plethysmography. Glucose uptake and ISI Index were calculated.

RESULTS

Peak-baseline muscle blood flow was higher in CONTROLS (3.32 ± 0.4) than in RELATIVES (0.53 ± 0.29), IGT (0.82 ± 0.2), DMA (1.44 ± 0.34), DMB (1.23 ± 0.35 ml/min/100 ml tissue), P < 0.001. Glucose uptake (AUC(0-360,) μmol/100 ml tissue) was higher in CONTROLS (1023 ± 132) than in RELATIVES (488 ± 42), IGT (458 ± 43), DMA (347 ± 63), DMB (543 ± 53), P < 0.001. ISI index, postprandial triglycerides and nonesterified-fatty acids behaved in a similar way. Peak-baseline muscle blood flow correlated positively with glucose uptake (r = 0.440, P = 0.001) and ISI index (r = 0.397, P = 0.003), and negatively with postprandial triglycerides (r = -0.434, P = 0.001) and nonesterified-fatty acids (r = -0.370, P = 0.005).

CONCLUSIONS

These results suggest that increase in muscle blood flow after a meal is impaired at all stages of type-2 diabetes. This defect influences glucose uptake and is associated with impaired lipid metabolism in the postprandial state.

Increased lipolysis but diminished gene expression of lipases in subcutaneous adipose tissue of healthy young males with intrauterine growth retardation

Intrauterine growth retardation (IUGR) is associated with a central fat distribution and risk of developing type 2 diabetes in adults when exposed to a sedentary Western lifestyle. Increased lipolysis is an early defect of metabolism in IUGR subjects, but the sites and molecular mechanisms involved are unknown. Twenty IUGR and 20 control (CON) subjects, aged 20-30 years, were studied before and after 10 days of bed rest using the glucose clamp technique combined with measurements of in vivo metabolism by microdialysis technique and blood flow by (133)Xe washout technique in subcutaneous abdominal (SCAAT) and femoral (SCFAT) adipose tissue. Additionally, mRNA expression of lipases was evaluated in biopsies from SCAAT. Lipolysis in SCAAT was substantially higher in IUGR than in CON subjects despite markedly lower mRNA expression of lipases. Blood flow was higher in IUGR compared with CON in both SCAAT and SCFAT. Whole body insulin sensitivity did not differ between groups and decreased after bed rest. After bed rest, SCAAT lipolysis remained higher in IUGR compared with CON, and SCFAT lipolysis decreased in CON but not in IUGR. Prior to the development of whole body insulin resistance, young men with IUGR are characterized by increased in vivo adipose tissue lipolysis and blood flow with a paradoxically decreased expression of lipases compared with CON, and 10 days of physical inactivity underlined the baseline findings. Subjects with IUGR exhibit primary defects in adipose tissue metabolism.

Impact of physical inactivity on subcutaneous adipose tissue metabolism in healthy young male offspring of patients with type 2 diabetes

OBJECTIVE

Physical inactivity is a risk factor for type 2 diabetes and may be more detrimental in first-degree relative (FDR) subjects, unmasking underlying defects of metabolism. Using a positive family history of type 2 diabetes as a marker of increased genetic risk, the aim of this study was to investigate the impact of physical inactivity on adipose tissue (AT) metabolism in FDR subjects.

RESEARCH DESIGN AND METHODS

A total of 13 FDR and 20 control (CON) subjects participated in the study. All were studied before and after 10 days of bed rest using the glucose clamp technique combined with measurements of glucose uptake, lipolysis, and lactate release from subcutaneous abdominal (SCAAT) and femoral (SCFAT) adipose tissue by the microdialysis technique. Additionally, mRNA expression of lipases was determined in biopsies from SCAAT.

RESULTS

Before bed rest, the FDR subjects revealed significantly increased glucose uptake in SCAAT. Furthermore, mRNA expression of lipases was significantly decreased in the SCAAT of FDR subjects. Bed rest significantly decreased lipolysis and tended to increase glucose uptake in the SCFAT of both CON and FDR subjects. In response to bed rest, SCAAT glucose uptake significantly increased in CON subjects but not in FDR subjects.

CONCLUSIONS

FDR subjects exhibit an abnormal AT metabolism including increased glucose uptake prior to bed rest. However, the differences between FDR and CON subjects in AT metabolism were attenuated during bed rest due to relatively more adverse changes in CON subjects compared with FDR subjects. Physical inactivity per se is not more deleterious in FDR subjects as compared with CON subjects with respect to derangements in AT metabolism.

Effect of physical training on insulin secretion and action in skeletal muscle and adipose tissue of first-degree relatives of type 2 diabetic patients

Physical training affects insulin secretion and action, but there is a paucity of data on the direct effects in skeletal muscle and adipose tissue and on the effect of training in first-degree relatives (FDR) of patients with type 2 diabetes. We studied insulin action at the whole body level and peripherally in skeletal muscle and adipose tissue as well as insulin-secretory capacity in seven FDR and eight control (CON) subjects before and after 12 wk of endurance training. Training improved physical fitness. Insulin-mediated glucose uptake (GU) increased (whole body and leg; P < 0.05) after training in CON but not in FDR, whereas glucose-mediated GU increased (P < 0.05) in both groups. Adipose tissue GU was not affected by training, but it was higher (abdominal, P < 0.05; femoral, P = 0.09) in FDR compared with CON. Training increased skeletal muscle lipolysis (P < 0.05), and it was markedly higher (P < 0.05) in subcutaneous abdominal than in femoral adipose tissue and quadriceps muscle with no difference between FDR and CON. Glucose-stimulated insulin secretion was lower in FDR compared with CON, but no effect of training was seen. Glucagon-like peptide-1 stimulated insulin secretion five- to sevenfold. We conclude that insulin-secretory capacity is lower in FDR than in CON and that there is dissociation between training-induced changes in insulin secretion and insulin-mediated GU. Maximal GU rates are similar between groups and increases with physical training.