Changes in serum lipids and blood glucose in non diabetic patients with metabolic syndrome after mixed meals of different composition

Changes in glucose-related parameters according to LDL-cholesterol concentration ranges in non-diabetic patients

The study focused on the changes in C-peptide, glycemia, insulin concentration, and insulin resistance according to LDL-cholesterol concentration ranges. The metabolic profile of individuals in the Czech Republic (n = 1840) was classified by quartiles of LDL-cholesterol into four groups with the following ranges: 0.46-2.45 (n = 445), 2.46-3.00 (n = 474), 3.01-3.59 (n = 459), and 3.60-7.18 mmol/l (n = 462). The level of glucose, C-peptide, insulin, and area of parameters during OGTT and HOMA IR were compared with a relevant LDL-cholesterol range. The evaluation involved correlations between LDL-cholesterol and the above parameters, F-test and t-test. Generally, mean values of glucose homeostasis-related parameters were higher with increasing LDL-cholesterol levels, except for mean HOMA IR values which rapidly increased (2.7-3.4) between LDL-cholesterol ranges of 3.00-3.59 and 3.60-7.18 mmol/l. Glucose, C-peptide, insulin concentrations, and the area of parameters reached greater changes especially after glucose load during OGTT (p ≤ 0.001). Considerable changes were already observed for the above parameters between groups with LDL-cholesterol ranges of 2.46-3.00 and 3.01-3.59 mmol/l. HOMA IR increased with higher LDL-cholesterol concentrations, but the differences in mean values were not statistically significant. Most important differences appeared in glucose metabolism at LDL-cholesterol concentrations of 3.60-7.18 mmol/l in comparison to LDL-cholesterol lower ranges. In particular, the areas of C-peptide, glucose, and insulin ranges showed statistically significant differences between all groups with growing LDL-cholesterol ranges. The variances of HOMA IR statistically differed between groups created according to LDL-cholesterol concentrations ranges.

Effect of acute hyperinsulinemia on magnesium homeostasis in humans

BACKGROUND

Insulin may influence magnesium homeostasis through multiple mechanisms. Acutely, it stimulates the shift of magnesium from plasma into red blood cells and platelets, and in vitro, it stimulates the activity of the TRPM6 channel, a key regulator of renal magnesium reabsorption. We investigated the impact of hyperinsulinemia on magnesium handling in participants with a wide range of insulin sensitivity.

METHOD

Forty-seven participants were recruited, including 34 nondiabetic controls and 13 with type 2 diabetes mellitus. After stabilization under fixed metabolic diet, participants underwent hyperinsulinemic-euglycemic clamp. Serum and urine samples were collected before and during hyperinsulinemia. Change in serum magnesium, urinary magnesium to creatinine (Mg²⁺ :Cr) ratio, fractional excretion of urinary magnesium (FEMg²⁺ ), and estimated transcellular shift of magnesium were compared before and during hyperinsulinemia.

RESULTS

Hyperinsulinemia led to a small but statistically significant decrease in serum magnesium, and to a shift of magnesium into the intracellular compartment. Hyperinsulinemia did not significantly alter urinary magnesium to creatinine ratio or fractional excretion of urinary magnesium in the overall population, although a small but statistically significant decline in these parameters occurred in participants with diabetes. There was no significant correlation between change in fractional excretion of urinary magnesium and body mass index or insulin sensitivity measured as glucose disposal rate.

CONCLUSIONS

In human participants, acute hyperinsulinemia stimulates the shift of magnesium into cells with minimal alteration in renal magnesium reabsorption, except in diabetic patients who experienced a small decline in fractional excretion of urinary magnesium. The magnitude of magnesium shift into the intracellular compartment in response to insulin does not correlate with that of insulin-stimulated glucose entry into cells.

Postprandial triglyceride response in normolipidemic, hyperlipidemic and obese subjects - the influence of polydextrose, a non-digestible carbohydrate

BACKGROUND

Three independent trials were conducted to evaluate postprandial triglyceride (TG) responses in subjects with different lipid metabolism. The effect of polydextrose (PDX), a soluble non-digestible carbohydrate, on postprandial response was also studied using practically relevant, high fat meal interventions.

METHODS

A total of 19 normolipidemic (average BMI 24.1 kg/m(2)), 21 overweight/hyperlipidemic (average BMI 29.6 kg/m(2)) and 18 obese/non-diabetic subjects (average BMI 33.6 kg/m(2)) were included in the study. On two separate occasions all subjects ate two high-fat meals (4293 kJ, 36% from fat), one with PDX (either 12.5 g or 15 g) and one without PDX during placebo-controlled, double-blind, crossover and randomized trials. To obtain the triglyceride measurements venous blood samples were taken before the consumption of the test meal and five times afterwards, up to 6 h post-test meal. The triglyceride responses were modeled using a mixed-effects linear model.

RESULTS

The key variables that explain the variation of the postprandial triglyceride response in the different subject groups were: baseline triglyceride concentration, time point, and PDX vs. placebo treatment (p < 0.05). The maximum postprandial TG concentration was more pronounced in hyperlipidemic group compared to normolipidemic (p < 0.001) or obese groups (p < 0.01). The modeled TG response analysis showed that irrespective of the study population PDX supplementation was one of the factors significantly reducing triglyceride response compared to the placebo treatment (p < 0.05).

CONCLUSIONS

Subjects with elevated fasting triglyceride levels display exaggerated and prolonged postprandial triglyceride responses. PDX, a soluble non-digestible carbohydrate, may offer a dietary concept for reducing the postprandial triglyceride response after the consumption of a meal containing a high concentration of fat.

Fasting time and lipid parameters: association with hepatic steatosis--data from a random population sample

Background

Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels.

Method

Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1–4 h, 4–8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression.

Results

At multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1–4 h and p = 0.0147 for 4–8 h among females; p < 0.0001 for 1–4 h and p = 0.0002 for 4–8 h among males) and reduced LDL cholesterol levels (p = 0.0003 for 1–4 h and p = 0.0327 for 4–8 h among males). Among males, hepatic steatosis represents an independent factor affecting elevated total cholesterol (p = 0.0278) and triglyceride concentrations (p = 0.0002).

Conclusion

Total and HDL cholesterol concentrations are subject to slight variations in relation to the duration of the pre-phlebotomy fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis.

Hyperinsulinemia and urinary calcium excretion in calcium stone formers with idiopathic hypercalciuria

CONTEXT

Calcium stone formers with idiopathic hypercalciuria (IH) are known to exhibit an exaggerated postprandial rise in urine calcium excretion compared with non-stone-forming individuals, and insulin has been proposed to mediate this difference.

OBJECTIVE

Our objective was to investigate the impact of hyperinsulinemia on urine calcium excretion in IH compared with non-stone-forming controls.

PARTICIPANTS AND SETTING

Ten IH patients and 22 control non-stone-forming subjects (8 lean and 14 overweight and obese) participated at the University of Texas Southwestern Clinical and Translational Research Center.

DESIGN

After stabilization on a fixed metabolic diet, subjects underwent a hyperinsulinemic-euglycemic clamp. Fasting 2-hour urine specimens were collected before and during the clamp.

MAIN OUTCOME MEASURES

Changes in fractional calcium excretion (F(E)Ca) during the clamp were compared between the 3 groups of subjects (IH, overweight/obese controls, and lean controls). Insulin sensitivity was measured by glucose disposal rate.

RESULTS

IH had significantly higher 24-hour urine calcium excretion than controls, and exhibited similar age, body mass index, and insulin sensitivity as overweight/obese controls. The hyperinsulinemic-euglycemic clamp resulted in a significant increase in serum insulin with no significant changes in serum calcium and glucose. This was accompanied by a small increase in F(E)Ca, with no significant differences between the 3 groups. There was no correlation between insulin sensitivity and 24-hour urine calcium or the change in F(E)Ca during the hyperinsulinemic clamp.

CONCLUSIONS

The rise in urine calcium associated with euglycemic hyperinsulinemia was small and not statistically different between IH and non-stone-forming controls. Insulin is therefore unlikely to play a significant pathogenetic role in IH.

Maternal deprivation exacerbates the response to a high fat diet in a sexually dimorphic manner

Maternal deprivation (MD) during neonatal life has diverse long-term effects, including affectation of metabolism. Indeed, MD for 24 hours during the neonatal period reduces body weight throughout life when the animals are maintained on a normal diet. However, little information is available regarding how this early stress affects the response to increased metabolic challenges during postnatal life. We hypothesized that MD modifies the response to a high fat diet (HFD) and that this response differs between males and females. To address this question, both male and female Wistar rats were maternally deprived for 24 hours starting on the morning of postnatal day (PND) 9. Upon weaning on PND22 half of each group received a control diet (CD) and the other half HFD. MD rats of both sexes had significantly reduced accumulated food intake and weight gain compared to controls when raised on the CD. In contrast, when maintained on a HFD energy intake and weight gain did not differ between control and MD rats of either sex. However, high fat intake induced hyperleptinemia in MD rats as early as PND35, but not until PND85 in control males and control females did not become hyperleptinemic on the HFD even at PND102. High fat intake stimulated hypothalamic inflammatory markers in both male and female rats that had been exposed to MD, but not in controls. Reduced insulin sensitivity was observed only in MD males on the HFD. These results indicate that MD modifies the metabolic response to HFD intake, with this response being different between males and females. Thus, the development of obesity and secondary complications in response to high fat intake depends on numerous factors.