Glycemic variability and hypoglycemia before and after Roux-en-Y Gastric Bypass and Sleeve Gastrectomy - A cohort study of females without diabetes

BACKGROUND

Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) lead to lower fasting glucose concentrations, but might cause higher glycemic variability (GV) and increased risk of hypoglycemia. However, it has been sparsely studied in patients without preoperative diabetes under normal living conditions.

OBJECTIVES

To study 24-hour interstitial glucose (IG) concentrations, GV, the occurrence of hypoglycemia and dietary intake before and after laparoscopic RYGB and SG in females without diabetes.

SETTING

Outpatient bariatric units at a community and a university hospital.

METHODS

Continuous glucose monitoring and open-ended food recording over 4 days in 4 study periods: at baseline, during the preoperative low-energy diet (LED) regimen, and at 6 and 12 months postoperatively.

RESULTS

Of 47 patients included at baseline, 83%, 81%, and 79% completed the remaining 3 study periods. The mean 24-hour IG concentration was similar during the preoperative LED regimen and after surgery and significantly lower compared to baseline in both surgical groups. GV was significantly increased 6 and 12 months after surgery compared to baseline. The self-reported carbohydrate intake was positively associated with GV after surgery. IG concentrations below 3.9 mmol/L were observed in 14/25 (56%) of RYGB- and 9/12 (75%) of SG-treated patients 12 months after surgery. About 70% of patients with low IG concentrations also reported hypoglycemic symptoms.

CONCLUSIONS

The lower IG concentration in combination with the higher GV after surgery, might create a lower margin to hypoglycemia. This could help explain the increased occurrence of hypoglycemic episodes after RYGB and SG.

Lower Interstitial Glucose Concentrations but Higher Glucose Variability during Low-Energy Diet Compared to Regular Diet-An Observational Study in Females with Obesity

This is an observational study of interstitial glucose (IG) concentrations, IG variability and dietary intake under free-living conditions in 46 females with obesity but without diabetes. We used continuous glucose monitoring, open-ended food recording and step monitoring during regular dietary intake followed by a low-energy diet (LED). Thirty-nine participants completed both study periods. The mean BMI at baseline was 43.6 ± 6.2 kg/m2. Three weeks of LED resulted in a mean weight loss of 5.2% with a significant reduction in diurnal IG concentration but with greater glycemic variability observed during LED. The mean 24 h IG concentration decreased from 5.8 ± 0.5 mmol/L during the regular diet period to 5.4 ± 0.5 mmol/L (p < 0.001) during LED, while the mean amplitude of glycemic excursion increased from 1.5 ± 0.7 to 1.7 ± 0.7 mmol/L (p = 0.031). The positive incremental area under the curve at breakfast was significantly larger for LED compared to regular diet. The daily fiber intake and the glycemic index of breakfast meals were significantly associated with the glycemic variability during regular dietary intake. In conclusion, the 24 h mean IG concentration was lower but with more pronounced glycemic variability during LED compared to a regular diet.

Increased circulating magnesium concentrations after Roux-en-Y gastric bypass surgery in patients with type 2 diabetes

BACKGROUND

Low circulating magnesium concentrations predict cardiovascular and all-cause mortality in patients with type 2 diabetes (T2D). Epidemiologic and clinical studies have indicated lower extra- and intracellular magnesium concentrations in patients with diabetes.

OBJECTIVE

We aimed to describe alterations, if any, in circulating magnesium concentrations after laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) in patients with obesity and T2D.

SETTING

Outpatient clinic of obesity and central hospital.

METHODS

Retrospective analysis of 1-year outcome of plasma magnesium (p-Mg) and glucometabolic status in all consecutive patients who underwent primary LRYGBP and who completed the follow-up visits, including biochemical test panels 6 and 12 months after surgery.

RESULTS

LRYGBP and complete follow-up visits were performed in 51 patients with T2D and 86 patients without T2D. All patients were given similar dietary advice and multivitamin and mineral supplementation after surgery. Before RYGB, the patients with T2D showed lower p-Mg compared with patients without T2D (.79 ± .06 mM and .82 ± .05 mM, respectively, P<.01). P-Mg was inversely correlated to fasting blood glucose and glycosylated hemoglobin levels. After surgery, mean p-Mg increased by 5.2% in the group with T2D compared with 1.4% in the patients without T2D (P<.01), ending at an equal level of .83 mM. The alterations in p-Mg were inversely related to the changes in fasting glucose and glycosylated hemoglobin concentrations.

CONCLUSION

The lowered p-Mg associated with impaired glucometabolic status in patients with T2D was increased after LRYGBP, reaching similar concentrations as in patients without T2D.

Do we need to measure vitamin B12 and magnesium in morbidly obese patients with type 2 diabetes mellitus?

OBJECTIVE

We aimed to investigate the prevalence of B12 deficiency in metformin-treated, morbidly obese, type 2 diabetes mellitus (T2DM) patients, compared to morbidly obese controls, as well as to evaluate the magnesium status.

DESIGN

Retrospective cross-sectional analysis of plasma vitamin B12, plasma magnesium, glucometabolic status and clinical measurements in all consecutive morbidly obese patients was conducted during 1 year.

SETTING

Outpatient Clinic of Obesity Care.

SUBJECTS

One hundred forty-seven patients were evaluated: 107 morbidly obese controls and 40 metformin-treated, morbidly obese patients with T2DM.

MAIN OUTCOME MEASURES

Circulating plasma concentrations of vitamin B12 (cobalamin), magnesium, clinical measurements and metformin medication.

RESULTS

There were differences between the two groups regarding age, sagittal diameter, glucose parameters and magnesium concentrations. Longer diabetes duration was associated with lower magnesium. Metformin-treated T2DM patients had lower magnesium (0.76±0.07 mmol/L) than controls (0.82±0.07 mmol/L). A subgroup analysis of 26 non-metformin-treated T2DM patients showed a normal magnesium concentration compared to controls, that is, 0.81±0.06 mmol/L. We found no statistical difference in B12 concentrations between the two groups.

CONCLUSION

To fully benefit from metformin medication, routine testing of B12 as well as magnesium in metformin-treated, morbidly obese patients should be performed, with consideration of substitution to avoid low levels.

Changes in liver volume and body composition during 4 weeks of low calorie diet before laparoscopic gastric bypass

BACKGROUND

Weight loss before laparoscopic Roux-en-Y gastric bypass (LRYGB) is desirable, because it can reduce liver volume and thereby facilitate the procedure. The optimal duration of a low-calorie diet (LCD) has not been established. The objective of this study was to assess changes in liver volume and body composition during 4 weeks of LCD.

METHODS

Ten women (aged 43±8.9 years, 114±12.1 kg, and body mass index 42±2.6 kg/m(2)) were examined on days 0, 3, 7, 14, and 28 after commencing the LCD. At each evaluation, body composition was assessed through bioelectric impedance analysis, and liver volume and intrahepatic fat content were assessed by magnetic resonance imaging. Serum and urine samples were obtained. Questionnaires regarding quality of life and LCD-related symptoms were administered.

RESULTS

In total, mean weight decreased by 7.4±1.2 kg (range 5.7-9.1 kg), and 71% of the weight loss consisted of fat mass according to bioelectric impedance analysis. From day 0 to day 3, the weight loss (2.0 kg) consisted mainly of water. Liver volume decreased by 18%±6.2%, from 2.1 to 1.7 liters (P<.01), during the first 2 weeks with no further change thereafter. A continuous 51%±16% decrease was seen in intrahepatic fat content. Systolic blood pressure, insulin, and lipids improved, while liver enzymes, glucose levels, and quality of life were unaffected.

CONCLUSION

A significant decrease in liver volume (18%) occurred during the first 2 weeks of LCD treatment, and intrahepatic fat gradually decreased throughout the study period. A preoperative 2-week LCD treatment seems sufficient in similar patients.

C3 and C4 are strongly related to adipose tissue variables and cardiovascular risk factors

BACKGROUND

In several reports, C3 and C4 have been linked to diabetes and cardiovascular disease (CVD). Here, we investigate this link and the degree of C3 activation in elderly individuals.

METHODS

In this study, C3 and C4 and the activation fragment C3a-desArg were analysed in 1016 subjects aged 70, in which blood pressure, lipid variables and fasting blood glucose were assessed.

RESULTS

C3 levels were related to all the investigated classical cardiovascular risk factors and the metabolic syndrome (BMI, waist circumference, fat distribution, blood pressure, blood glucose levels, TG) except total cholesterol and LDL cholesterol in a highly significant fashion (Spearman up to 0,5; P < 0·0001). C4 and C3a-desArg were associated in the same fashion but less significantly, while the ratios C4/C3 or C3a-desArg/C3 were not, indicating that the association was not directly related to complement activation. The levels C3 and to a lesser degree C4 and C3a-desArg were associated particularly with CRP, but also with E-selectin and ICAM-1. In addition, C3 and C4 levels were shown to decline significantly in 15 female subjects enrolled in a weight-reduction programme over 4 months.

CONCLUSION

A strong relation between C3, C4 and C3a-desArg levels, adipose tissue and risk factors of CVD was established. The data support that the adipose tissue produces complement components and generates initiators of inflammation, such as C3a and C5a, able to trigger a cyto/chemokine response, in proportion to the amount of adipose tissue. This corroborates the concept that complement contributes to the low-grade inflammation associated with obesity.

Increased plasma magnesium concentrations 3 years after biliopancreatic diversion with duodenal switch

BACKGROUND

Biliopancreatic diversion with duodenal switch, BPD-DS, is a surgical procedure for treatment of super obese patients. It renders very good weight results and it strongly reduces the incidence of type 2 diabetes. One important mechanism of weight reduction after BPD-DS is malabsorption. Hypomagnesemia is an established cardiovascular risk factor. While it is well-known that magnesium levels decline after jejuno-ileal bypass and increase after gastric bypass surgery, information on how magnesium status is affected by BPD-DS is scant. The aim of the present study was to evaluate plasma magnesium concentrations (P-Mg) after BPD-DS.

METHODS

Thirty-one patients, all Caucasians (9 diabetics, 12 men, age 38 ± 8 years, weight 159 ± 22 kg, body mass index (BMI) 53.9 ± 5.2 kg/m(2)) underwent BPD-DS. We evaluated weight, glycated hemoglobin levels (HbA1c) and P-Mg preoperatively as well as at 1 and 3 years after surgery. All subjects were treated with vitamin and mineral substitution after surgery, including 100 mg of magnesium salt. P-Mg was analyzed with respect to changes over time, correlation to BMI and HbA1c levels before and 3 years after surgery.

RESULTS

The plasma magnesium concentrations increased by 15 % from 0.77 ± 0.07 to 0.88 ± 0.09 mmol/l over 3 years (p < 0.001). The weight loss was 71 ± 25 kg. No patient had diabetes at follow-up. No correlations between P-Mg and BMI or HbA1c were seen.

CONCLUSIONS

Although exerting much of its weight-reducing effect by a malabsorptive mechanism, BPD-DS yields a rise in P-Mg 3 years postoperatively, possibly contributing to the improved metabolic state after this operation.

Platelet counts and liver enzymes after bariatric surgery

BACKGROUND

Obesity is characterized by liver steatosis, chronic inflammation, and increased liver enzymes, that is, gamma-glutamyltransferase (GGT) and alanine aminotransferase (ALT), markers for nonalcoholic fatty liver disease (NAFLD) and liver fat content. Increased platelet counts (PCs) are associated with inflammatory conditions and are a valuable biomarker of the degree of fibrosis in NAFLD. We investigated alterations in PC, GGT, and ALT after biliopancreatic diversion with duodenal switch (BPD-DS) and Roux-en-Y gastric bypass (RYGBP).

METHODS

Ten morbidly obese patients (body mass index, BMI: 53.5 ± 3.8 kg/m(2)) who underwent BPD-DS were evaluated preoperatively (baseline) and 1 year (1st followup) and 3 years (2nd followup) after surgery and compared with 21 morbidly obese patients (BMI: 42.3 ± 5.2 kg/m(2)) who underwent RYGBP.

RESULTS

Over the 3 years of followup, changes in BPD-DS and RYGBP patients (BPD-DS/RYGBP) were as follows: BMI (-44%/-24%), GGT (-63%/-52%), and ALT (-48%/-62%). PC decreased (-21%) statistically significantly only in BPD-DS patients.

CONCLUSIONS

Morbidly obese patients treated by RYGBP or BPD-DS show sustained reductions in BMI, ALT, and GGT. The decrease in PC and liver enzymes after BPD-DS may reflect a more pronounced decrease of liver-fat-content-related inflammation and, as a result, a lowered secondary thrombocytosis.

Changes in erythrocyte sedimentation rate, white blood cell count, liver enzymes, and magnesium after gastric bypass surgery

Background. Roux-en-Y gastric bypass (RYGBP) is an established method for treatment of obesity, a condition of chronic inflammation with liver steatosis, characterised by increased erythrocyte sedimentation rate (ESR), white blood cell count (WBC), liver enzymes, and decreased magnesium (Mg). We investigated alterations, if any, in ESR, WBC, alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), and Mg after RYGBP. Methods. 21 morbidly obese nondiabetic patients who underwent RYGBP surgery were evaluated preoperatively (baseline), then 1 year (1st followup) and 3.5 years (2nd followup) after RYGBP and compared to an untreated control group. Results. Body mass index, ESR, WBC, ALT, and GGT were all significantly reduced at 1 year in the RYGBP group (30%, 35%, 20%, 45%, and 57%, resp.) while Mg increased by 6%, compared to control group (P = 0.001-0.009). Conclusions. Obese patients treated by RYGBP show sustained reductions in ESR, WBC, ALT, and GGT possibly due to reduced liver steatosis and increased Mg.

Gastric bypass promotes more lipid mobilization than a similar weight loss induced by low-calorie diet

Background. Recently, we found large reductions in visceral and subcutaneous fat one month after gastric bypass (GBP), without any change in liver fat content. Purpose. Firstly to characterize weight loss-induced lipid mobilization after one month with preoperative low-calorie diet (LCD) and a subsequent month following GBP, and secondly, to discuss the observations with reference to our previous published findings after GBP intervention alone. Methods. 15 morbidly obese women were studied prior to LCD, at GBP, and one month after GBP. Effects on metabolism were measured by magnetic resonance techniques and blood tests. Results. Body weight was similarly reduced after both months (mean: -8.0 kg, n = 13). Relative body fat changes were smaller after LCD than after GBP (-7.1 ± 3.6% versus -10 ± 3.2%, P = .029, n = 13). Liver fat fell during the LCD month (-41%, P = .001, n = 13) but was unaltered one month after GBP (+12%). Conclusion. Gastric bypass seems to cause a greater lipid mobilization than a comparable LCD-induced weight loss. One may speculate that GBP-altered gastrointestinal signalling sensitizes adipose tissue to lipolysis, promoting the changes observed.

Effect of a vegetable-oil emulsion on body composition; a 12-week study in overweight women on a meal replacement therapy after an initial weight loss: a randomized controlled trial

Purpose

The maintenance of an obtained lower weight level is often found to be difficult. The aim of this study was to determine weight maintenance after an initial weight loss by consumption of a meal replacement with a vegetable-oil emulsion associated with prolonged satiety.

Methods

After a 6-week weight loss period with very low calorie diet (VLCD), subjects with >5% body weight (BW) loss were randomized to a 12-week weight maintenance follow-up period, comparing a partial meal replacement diet containing a vegetable-oil emulsion (test) or dairy fat (control). Anthropometric data and safety variables were collected at baseline and after 4, 8 and 12 weeks.

Results

A significant weight loss was observed during the 12-week weight maintenance diet in the test and control group, respectively; 1.0 ± 2.1 kg (p < 0.05) versus 1.3 ± 2.1 kg (p < 0.05) with no significant difference between the groups. Body fat mass (BFM) decreased significantly (p < 0.05) in the test group (−1.7%) compared to the control group (−0.8%).

Conclusions

Addition of a vegetable-oil emulsion to a meal replacement weight maintenance program after an initial weight loss using VLCD was associated with decreased BFM by 0.9% without any change in BW between the two groups.

Effect of fat emulsion (Fabuless) on orocecal transit time in healthy men

BACKGROUND

Given the growing prevalence of overweight and related health consequences, there is increased interest in the search for novel dietary strategies for weight control. A food ingredient, an emulsion based on palm and oat oil (Fabuless, previously known as Olibra), has been associated with short-term reductions of food intake, induction of satiety, alternation in the satiety hormones, as well as long-term effects on weight control. The mechanism by which it can exert these effects is so far unclear, though it has been suggested that the "ileal break" may play a role in increasing gastrointestinal transit time. The aim of this study was to investigate the effects of this stable fat emulsion on orocecal transit time in healthy men.

MATERIAL AND METHODS

In a controlled, double-blind, cross-over-designed study, 15 healthy men (aged 20-59 years, body mass index (BMI) 22-28), randomly allocated to two treatments, consumed the stable fat emulsion or a milk fat in yoghurt during two days of investigation, with an interval of 1 week. Orocecal transit time was determined by following blood sulfapyridine levels, which is a metabolite of salazopyrine in the colon.

RESULTS

A statistically significant delay in the appearance of sulfapyridine in serum was obtained after active treatment versus control treatment, corresponding to a 45-min longer orocecal transit time due to fat emulsion consumption.

CONCLUSIONS

This study provides the first evidence to suggest that this stable fat emulsion may affect the ileal brake mechanism by slowing down the gastrointestinal transit time, which might explain the weight control and appetite suppression previously observed in association with this emulsion.

Biochemical risk factors for development of obesity in first-episode schizophrenia

Obesity is a serious health issue for many patients with schizophrenia. There is a lack of predictors for and understanding of the development of obesity in the early phase of the illness. Therefore we investigated a set of routine biochemistry variables in blood as predictors of the development of obesity and weight gain over 5 years in an observational cohort study of patients with first-episode schizophrenia (n=59). Twelve percent of the patients were obese at baseline and 37% were obese at the 5-year follow-up. The mean body mass index (BMI) change over 5 years was a 4.1 kg/m(2) increase (4.5 SD). Obesity was predicted by baseline hemoglobin levels (odds ratio per standard deviation [OR/SD] 3.3, 95% confidence interval [CI] 1.4 to 7.5), red blood cell count (OR/SD 2.6, 95% CI 1.2 to 5.5), hematocrit (OR/SD 2.8, 95% CI 1.3 to 5.9), gamma-glutamyltransferase (OR/SD 2.8, 95% CI 1.2-6.3) and creatinine (OR/SD 3.1, 95% CI 1.2 to 8.0). After adjustment for baseline BMI, the associations were attenuated for gamma-glutamyltransferase and creatinine. Low baseline BMI was associated with a greater BMI increase. The major conclusion is that easily available routine biochemistry markers can be useful in predicting the development of obesity in first-episode schizophrenia. The mechanisms underlying the observed associations are unknown, but the predictors identified in this study could signify dehydration or insulin resistance. These observations open a new window to future research on the mechanisms underlying the development of obesity in schizophrenia.

Gastric bypass alters the dynamics and metabolic effects of insulin and proinsulin secretion

AIMS

Hyperproinsulinaemia is associated with obesity and is a risk factor for Type 2 diabetes. We explored the dynamics of proinsulin and insulin and postprandial effects on glucose and lipids in subjects who had undergone gastric bypass (GBP) surgery compared with morbidly obese (MO) subjects and normal weight control subjects (NW).

METHODS

Subjects free from diabetes were recruited: 10 previously MO subjects [body mass index (BMI) +/- sd, 34.8 +/- 6.2 kg/m2] who had undergone GBP surgery, 10 MO subjects (BMI 44 +/- 3.1 kg/m2) and 12 NW control subjects (BMI 23.2 +/- 2.4 kg/m2). After an overnight fast, a standard meal (2400 kJ) was ingested and glucose, proinsulin, insulin free fatty acids and triglycerides were determined up to 180 min.

RESULTS

Fasting proinsulin was similar in the GBP group and NW control subjects, but threefold increased in MO subjects (P < 0.05). Postprandial AUC for glucose was similar in the three groups and AUC for proinsulin was high in MO, intermediate in the GBP group and lowest in NW control subjects (P for trend = 0.020). Postprandial proinsulin at 60 min was similar in the GBP group and MO subjects and twofold higher than in NW control subjects. Postprandial proinsulin at 180 min was normal in the GBP group, but fivefold increased in MO subjects (P = 0.008). Insulin increased rapidly at 30 min in the GBP group and was normal at 90 min, whereas insulin was still increased at 90-180 min in the MO subjects (P < 0.001).

CONCLUSIONS

MO subjects, free from diabetes, have elevated proinsulin concentrations in the fasting as well as the postprandial phase. After GBP surgery markedly lower fasting and postprandial proinsulin concentrations were observed, although BMI was higher compared with NW control subjects.

Skeletal muscle magnesium content is correlated with plasma glucose concentration in patients with essential hypertension treated with lisinopril or bendrofluazide

The association between change in glucose metabolism and change in skeletal muscle magnesium (Mg) concentration induced by antihypertensive treatment was evaluated in 37 patients with essential hypertension randomly treated with either lisinopril or bendrofluazide. Before and after 6 months of treatment, skeletal muscle biopsies were performed, glucose tolerance was determined by oral (OGTT) and intravenous glucose tolerance tests (IVGTT), and insulin sensitivity was assessed by the hyperinsulinemic euglycemic clamp technique. An inverse relationship was found between the treatment-induced change in fasting plasma glucose concentration and change in skeletal muscle Mg concentration (r = -0.39, P < .05). However, there was no significant correlation between skeletal muscle Mg content and either insulin sensitivity measured by the hyperinsulinemic euglycemic clamp test or glucose tolerance evaluated by IVGTT and OGTT. In conclusion, an increased circulating glucose concentration was correlated with a decreased Mg concentration in skeletal muscle during antihypertensive treatment. However, the Mg concentration in skeletal muscle did not significantly predict the insulin sensitivity or glucose tolerance.

Magnesium infusion improves endothelium-dependent vasodilation in the human forearm

The effect of intra-arterial magnesium infusion on endothelium-dependent vasodilation (EDV) in the forearm was studied in nine young healthy students (four men and five women). The EDV was assessed as forearm blood flow (FBF), measured by venous occlusion plethysmography, during infusion of methacholine (MCh). Endothelium-independent vasodilation (EIDV) was defined as FBF during infusion of sodium nitroprusside (SNP). During magnesium infusion in the brachial artery, 0.066 mmol/min, the concentration of ionized magnesium in venous plasma in the infused arm increased by 114%, from 0.59 (SD 0.04) to 1.26 (0.34) mmol/L (P = .0002). The FBF at baseline (ie, before administration of MCh or SNP) increased from 3.5 (1.1) to 7.3 (3.4) mL/min/100 mL tissue during magnesium infusion (P = .002). During low-dose MCh administration (2 microg/min), FBF increased by 24%, from 15.4 (5.5) to 19.1 (6.8) mL/min/100 mL tissue (P = .04), and during high-dose MCh administration (4 microg/min) FBF increased by 18%, from 20.3 (6.4) to 24.0 (7.2) mL/min/100 mL tissue (P = .04). The EIDV did not change significantly. Systemic blood pressure was not significantly altered by magnesium infusion. No change in FBF either at rest or during infusion of MCh or SNP was observed during the time-control protocol. In conclusion, this in vivo study showed that intraarterial magnesium infusion increased EDV in the infused human forearm, which is in accordance with findings in previous in vitro and animal experiments.

Systolic blood pressure alterations during hyperinsulinemia are related to changes in ionized calcium status

BACKGROUND

A correlation between changes in ionized calcium status and changes in systolic blood pressure (BP) has previously been observed during induced euglycemic hyperinsulinemia in patients with essential hypertension. The objective of this study was to evaluate associations between alterations in ion status and BP changes during euglycemic hyperinsulinemia in healthy normotensive subjects.

METHODS

Ion status in plasma and BP were measured before and at the end of euglycemic hyperinsulinemic clamp tests performed in 41 healthy normotensive volunteers.

RESULTS

During euglycemic hyperinsulinemia plasma sodium increased by 1% (P < .0001), ionized calcium (iCa) by 5% (P < .0001), and ionized magnesium (iMg) by 4% (P < .01), whereas potassium decreased by 10% (P < .0001). The changes in plasma iCa and iMg correlated significantly to changes in systolic BP (r = -0.38, P < .02; r = -0.32, P < .05, respectively), but the correlation between changes in iMg and changes in systolic BP did not remain significant in a multiple regression model. The glucose infusion rate correlated inversely to the change in iMg (r = -0.39, P < .01).

CONCLUSIONS

The group mean systolic BP was unaltered during induced euglycemic hyperinsulinemia in healthy normotensive subjects; however, a more pronounced increase in the circulating iCa concentration was associated with a greater decline in systolic BP, which is in accordance with previous observations in patients with essential hypertension. The group mean diastolic BP was decreased; however, the lowered diastolic BP was not correlated to changes in ion status.

Serum magnesium status during lipid-lowering drug treatment in non-insulin-dependent diabetic patients

Serum magnesium concentration (S-Mg) has been reported to be inversely associated with atherogenic lipid fractions and with blood glucose concentrations. In some studies on humans, oral magnesium supplementation has been found to improve the lipoprotein balance. Against this background the present study was undertaken to determine whether reductions in atherogenic lipid fractions are associated with S-Mg alterations. Total S-Mg was measured in 23 patients with non-insulin-dependent diabetes mellitus (NIDDM) treated with the lipid-lowering drugs gemfibrozil and simvastatin in a double-blind cross-over study. The mean S-Mg at the end of the initial placebo period, ie, before active treatment, was 0.80 (SD 0.06) mmol/L. Treatment with gemfibrozil 600 mg twice daily for 4 months decreased S-Mg by 0.02 mmol/L (P =.02), and treatment with simvastatin 10 mg daily for 4 months again decreased S-Mg by 0.02 mmol/L (P =.10; not significant [NS]) The changes in S-Mg during the 2 different treatment periods were closely correlated (r = 0.66, P <.001). Fasting plasma glucose concentrations increased significantly by 17% during both drug regimens. The changes in fasting plasma glucose and S-Mg were significantly correlated both during gemfibrozil treatment (r = -0.56, P <.01) and during treatment with simvastatin (r = -0.44, P <.05). Changes in glucose tolerance or insulin sensitivity did not correlate to changes in S-Mg. The associations between changes in serum very-low-density lipoprotein (VLDL) fractions and S-Mg did not reach statistical significance (r = -0.37, P <.10). Changes in low-density lipoprotein (LDL) cholesterol and S-Mg did not correlate. In conclusion, total S-Mg concentration decreased during treatment with gemfibrozil and simvastatin in patients with NIDDM. During both drug regimens changes in S-Mg status were inversely correlated to changes in plasma glucose concentrations, while changes in lipid status were not significantly correlated with changes in S-Mg.

Serum aldosterone changes during hyperinsulinemia are correlated to body mass index and insulin sensitivity in patients with essential hypertension

OBJECTIVE

To measure the effects of hyperinsulinemia on serum electrolyte status and associated hormones, and on serum free fatty acid (FFA) concentrations, in patients with essential hypertension.

DESIGN AND METHODS

The serum electrolyte status (Na, K, Ca, ionized Ca, Mg, P, pH) and associated hormones [plasma renin activity (PRA), serum parathyroid hormone (PTH) and aldosterone concentrations], and FFA were measured during an euglycemic hyperinsulinemic clamp test in 49 patients with untreated essential hypertension.

RESULTS

Serum potassium, phosphate, PTH, and FFA concentrations decreased during hyperinsulinemia, while serum ionized calcium concentration, pH, and PRA increased significantly (P < 0.05). The changes in serum potassium and magnesium were both inversely related to the insulin-mediated glucose uptake (r= -0.62, P< 0.0001; r= -0.31, P< 0.05, respectively). Both body mass index (BMI) and insulin-mediated glucose disposal were significantly correlated to the changes in serum aldosterone concentration during hyperinsulinemia (r = 0.41, P < 0.01; r = -0.40, P < 0.01, respectively). The change in serum aldosterone during the clamp test was not significantly related to the change in PRA, but tended to correlate to the change in potassium concentration (r= 0.25, P= 0.10). A less pronounced reduction in FFA during induced hyperinsulinemia was associated with low insulin sensitivity (r= -0.35, P< 0.05).

CONCLUSION

Hypertensive patients with normal BMI and a more pronounced glucose uptake showed a larger serum potassium decline and lowered aldosterone concentrations during induced euglycemic hyperinsulinemia. Insulin-resistant patients showed a less pronounced reduction in FFA during hyperinsulinemia. The observations in the present study may indicate that alterations in aldosterone and FFA metabolism might be linked to the insulin resistance metabolic syndrome.

Blood pressure changes in relation to sodium and calcium status in induced hyperinsulinemia

Insulin increases renal sodium reabsorption which may contribute to hypertension. However, acute insulin administration may result in vasodilation. The aim of the present study was to investigate effects on blood pressure and alterations in ion status during hyperinsulinemia. Blood pressure and serum sodium and ionized calcium concentrations were measured before and at the end of euglycemic hyperinsulinemic clamp tests performed in 45 patients with essential hypertension. Both the systolic and the diastolic blood pressure decreased, by 4% (p < 0.05) and 3% (p < 0.05), respectively. Circulating ionized calcium concentration increased by 2% (p < 0.001), and the ratio between circulating sodium and ionized calcium concentrations decreased. The changes in circulating sodium concentration correlated to changes in systolic blood pressure (SBP; r = 0.36, p = 0.05). Both ionized calcium concentrations and the ratio between circulating sodium and ionized calcium concentrations correlated to changes in SBP during hyperinsulinemia (r = -0.41, p = 0.03, r = 0.56, p < 0.01, respectively). The changes in ion status were not significantly correlated to age, body mass index or insulin sensitivity. In conclusion, a more pronounced increase in circulating ionized calcium concentration and reduction in the ratio between sodium and ionized calcium concentrations was associated with a greater blood pressure decline during the hyperinsulinemic clamp test when performed in hypertensive patients.

Induction of insulin resistance by beta-blockade but not ACE-inhibition: long-term treatment with atenolol or trandolapril

The effects on glucose metabolism by the beta-blocker atenolol and the angiotensin-converting enzyme (ACE)-inhibitor trandolapril were investigated in a randomised double-blind parallel group study of patients with primary hypertension. Twenty-six patients were treated with 50-100 mg atenolol and 27 patients with 2-4 mg trandolapril o.d. Intravenous glucose tolerance tests, euglycaemic hyperinsulinaemic clamps and serum lipid measurements were performed after 8 and 48 weeks of active treatment. After 48 weeks insulin sensitivity was reduced by 23% by atenolol while it remained unchanged during trandolapril treatment (+0.5%, P = 0.0010 for difference between treatments, ANCOVA). The effect on triglycerides (+22% vs -8.5%) and high-density lipoprotein cholesterol (-13% vs +0.7%) also differed significantly between atenolol and trandolapril. Results after 8 weeks were similar. Glucose tolerance was not affected by either drug. Atenolol reduced diastolic blood pressure (DBP) better than trandolapril (-15.3 mm Hg vs -6.6 mm Hg for supine DBP after 48 weeks, P = 0.012). The difference in effect on insulin sensitivity between the drugs corresponded to 25% of the baseline values of insulin sensitivity, and persisted over 48 weeks of treatment. The choice of antihypertensive treatment could influence the risk of diabetes associated with treated hypertension. Journal of Human Hypertension (2000) 14, 175-180.

Moxonidine improves insulin sensitivity in insulin-resistant hypertensives

OBJECTIVE

To study whether insulin sensitivity and insulin response are altered by moxonidine treatment in obese patients with mild essential hypertension.

DESIGN

a prospective, double-blind, placebo-controlled, randomized, parallel group study.

PATIENTS AND METHODS

77 patients with mild essential hypertension and body mass index > 27 were enrolled. A placebo run-in period of 1-3 weeks was followed by 8-9 weeks of double-blind treatment with either placebo or moxonidine. Patients receiving antihypertensive drugs underwent a 4-week wash-out period preceeding the placebo run-in. Insulin sensitivity was evaluated by hyperinsulinaemic euglycaemic clamp test. Insulin response was measured during intravenous glucose tolerance test.

RESULTS

72 patients completed the study. No serious adverse events were reported. The glucose infusion rate (M value), and insulin sensitivity index (M/I ratio) increased in the moxonidine-treated subjects by 10% (P = 0.025), and 11% (P = 0.04), respectively, whereas the values in the placebo group remained unchanged. In the predefined insulin-resistant subgroup with M/I ratio < 3.6 at baseline, glucose infusion rate and insulin sensitivity index increased by 21% whereas values in the placebo group remained unchanged. A between-group comparison showed a statistical significant difference in the M value (P = 0.026) and a borderline statistical difference in the M/I ratio (P = 0.056) in favour of moxonidine. No statistically significant effects were seen in the subgroup with a M/I ratio > or = or 3.6 at baseline. The insulin secretion in response to glucose stimulation was unaffected in insulin-resistant as well as in insulin-sensitive hypertensive patients.

CONCLUSION

Moxonidine treatment improved insulin sensitivity in insulin-resistant, obese patients with mild hypertension, but not in insulin-sensitive obese subjects with mild hypertension, when compared to placebo. Insulin response to glucose stimulation was unaffected. The drug was well tolerated.

Skeletal muscle angiotensin-converting enzyme and its relationship to blood pressure in primary hypertension and healthy elderly men

The aim of this study was to investigate the relationships between angiotensin-converting enzyme (ACE) activity in serum and skeletal muscle to blood pressure and the long-term antihypertensive effects of fosinopril and atenolol. We examined 50 hypertensive patients randomized to receive 20 mg fosinopril or 50 mg atenolol daily for 16 weeks. ACE activity was measured in biopsy specimens from skeletal muscle. Measurements of office and ambulatory blood pressure, serum ACE, and left ventricular wall thickness were also performed. The same investigations were performed in a cross-sectional study of 50 healthy elderly men. Muscle ACE correlated inversely to blood pressure in cross-sectional analyses in both populations (p < 0.05). During atenolol treatment muscle ACE activity tended to increase (14%, p = 0.059), and this increase correlated inversely to the changes in standing systolic and diastolic blood pressure (r = -0.62, p = 0.0044, and r = 0.54, p = 0.016, respectively). Muscle ACE was also inversely correlated to left ventricular wall thickness when the two populations were pooled (r =-0.29, p = 0.0053). In the fosinopril group, muscle ACE activity was not different during treatment than at baseline (-2. 1%, p = 0.68). The inverse relationship between blood pressure and muscle ACE levels in this study indicate that muscle tissue ACE levels are influenced by haemodynamic factors in humans.

Insulin resistance in essential hypertension is related to plasma renin activity

A high plasma renin activity (PRA) has previously been related to several cardiovascular risk factors as well as to later cardiovascular events. As insulin resistance has been suggested as the unifying factor in the insulin resistance metabolic syndrome, insulin resistance was evaluated by the euglycaemic hyperinsulinaemic clamp technique in 50 untreated hypertensive subjects in whom PRA and serum aldosterone were measured together with lipids and an intravenous glucose tolerance test (IVGTT). PRA was inversely related to insulin-mediated glucose disposal during the clamp (r=-0.31, P < 0.05), as well as to fasting insulin (r=0.32, P < 0.05) and to insulin at 60 min at the IVGTT (r=0.30, P < 0.05), but not to other risk factors. Serum aldosterone was not related to any of the metabolic risk factors. In conclusion, the present investigation showed that insulin resistance is associated with elevated levels of PRA in patients with untreated essential hypertension. It thus seems as if a high activity in the renin system should be included in the disturbances included in the insulin resistance metabolic syndrome, a syndrome with a major impact on future cardiovascular events.

Atherogenic lipid fractions are related to ionized magnesium status

The plasma concentration of ionized magnesium (iMg++), the serum total magnesium concentration (tMg), and lipoprotein status were assessed in 29 elderly men with impaired insulin sensitivity but who were otherwise healthy and not receiving antidiabetic pharmacologic treatment. Plasma iMg++ was inversely correlated with serum concentrations of VLDL cholesterol (r = -0.39, P < 0.04), LDL cholesterol (r = -0.57, P < 0.002), total cholesterol (r = -0.55, P < 0.002), VLDL triacylglycerol (r = -0.36, P < 0.05), LDL triacylglycerol (r = -0.48, P < 0.01), and total triacylglycerol (r = -0.41, P < 0.03). The serum total magnesium concentration also tended to be inversely correlated with these lipid fractions, but not significantly so. Furthermore, iMg++ was inversely correlated with the apolipoprotein B concentration (r = -0.56, P < 0.002) and with the ratio of apolipoprotein B to A-I in serum (r = -0.58, P < 0.001). The corresponding values for tMg were r = -0.37 (P = 0.05) and r = -0.37 (P = 0.05), respectively. Insulin increment and the area under the insulin curve during an intravenous glucose tolerance test were inversely correlated with iMg++ [r = -0.56 (P < 0.01) and r = -0.64 (P < 0.0005), respectively], but were not significantly correlated with tMg. Insulin-mediated glucose uptake and the insulin sensitivity index during the hyperinsulinemic euglycemic clamp test were not significantly correlated with tMg (r = 0.05 and 0.12, respectively; NS) nor with iMg++ (r = 0.23 and 0.31, respectively; NS). Atherogenic lipid fractions and some glucometabolic variables were more closely correlated with iMg++ than with tMg.

The alterations in insulin sensitivity during angiotensin converting enzyme inhibitor treatment are related to changes in the calcium/magnesium balance

The present analysis was undertaken to investigate the relations between alterations in mineral factors, especially the balance between serum calcium and magnesium concentrations (S-Ca and S-Mg, respectively), and variables reflecting glucose and lipid metabolism during angiotensin converting enzyme (ACE) inhibitor treatment. A total of 96 patients with essential hypertension, participating in four double-blind studies with four different ACE inhibitors and similar protocols, were included. At the end of the initial placebo period and at the end of the period of active drug treatment, a hyperinsulinemic euglycemic clamp test was carried out, lipoprotein status was assessed, and the concentrations of serum electrolytes were measured. The serum ACE activity was determined in the group treated with fosinopril. Changes in insulin sensitivity index (M/I) were directly correlated to alterations in S-Mg (r = 0.24, P < .02), and inversely correlated to changes in S-Ca (r = -0.19, P = .07) and the ratio between serum calcium and magnesium concentrations (Ca/Mg) (r = -0.27, P < .008). The change in total serum triglycerides (S-Tg) was inversely correlated to the change in S-Mg (r = -0.35, P < .0005), and directly correlated to the change in Ca/Mg ratio (r = 0.36, P < .0004). The reduction in serum ACE activity correlated to a more pronounced increase in S-Mg r = -0.62, P < .002), and decrease in the Ca/Mg ratio (r = 0.73, P = .0002). We conclude that the changes in the studied metabolic variables and serum ACE activity during ACE inhibitor treatment are related to alterations in mineral status and the balance between calcium and magnesium concentrations in serum.

Urapidil treatment decreases plasma fibrinogen concentration in essential hypertension

The effects of antihypertensive drugs on cardiovascular metabolic risk factors were monitored in 42 patients with essential hypertension (diastolic blood pressure [DBP] >95 mm Hg). In a double-blind randomized parallel-group study, they were treated with atenolol 50 mg once per day (n = 25) or urapidil 60 mg twice per day (n = 17), a peripheral alpha1-receptor blocker with an additional central serotonin 1A (5HT1A) receptor agonistic effect, for 12 weeks. Plasma fibrinogen concentration decreased by 24% (P < .0001) during urapidil treatment and by 9% (P = .05) during atenolol treatment, with the effects of the two drugs differing significantly. Plasminogen activator inhibitor (PAI) activity tended to increase by 17% (nonsignificant [NS]) in the atenolol-treated group and to decrease by 4% (NS) in the urapidil group. Differences between the effects of the two drugs on very-low-density lipoprotein (VLDL) triglycerides (TG) and on total TG were significant. During urapidil medication, these two parameters were reduced by 22% and 13%, respectively, but the changes were nonsignificant (P = .11 and P = .14, respectively). In contrast, atenolol treatment caused a significant increase in both VLDL TG and total TG of 31% and 21%, respectively. Hemoglobin A1c (HbA1c) increased by 4% (P = .06) during atenolol treatment, but was unaffected by urapidil. There were no significant changes within or between atenolol- and urapidil-treated groups regarding glucose disposal on an oral glucose tolerance test (OGTT) or the insulin sensitivity index on a hyperinsulinemic-euglycemic clamp test. In conclusion, urapidil treatment was characterized by neutral or favorable effects on several variables associated with the metabolic syndrome. Atenolol treatment had neutral properties in some metabolic aspects, but deleterious effects on lipid status.

The blood pressure response to antihypertensive treatment with lisinopril or bendrofluazide is related to the calcium and magnesium contents in skeletal muscle

To evaluate the association between skeletal muscle mineral balance and effect of antihypertensive treatment, 37 patients with essential hypertension, randomly treated with either lisinopril or bendrofluazide, were investigated with skeletal muscle biopsies before and after 6 months of treatment. The ratio between calcium and magnesium concentrations in skeletal muscle prior to treatment predicted the blood pressure response during active treatment (r = -0.38, P < .02). During treatment the change in blood pressure was related to the change in muscle Ca/Mg ratio (r = 0.35, P < .05), especially in the patients treated with lisinopril. Thus, an association between the calcium and magnesium balance in skeletal muscle and the blood pressure response to antihypertensive treatment was found in the present study.

Electrolyte changes and metabolic effects of lisinopril/bendrofluazide treatment. Results from a randomized, double-blind study with parallel groups

The metabolic effects of lisinopril and bendrofluazide therapy were studied in 61 patients with essential hypertension in a randomized, double-blind study with parallel groups. The insulin sensitivity index, measured by hyperinsulinemic euglycemic clamp test, decreased by 22% (P < .01) during bendrofluazide treatment and by 15% (NS) during lisinopril treatment. The initial insulin response at intravenous glucose tolerance test (IVGTT) increased by 21% (P < .05) during lisinopril treatment but decreased by 13% (P < .05) during treatment with bendrofluazide, and in addition, the glucose disappearance rate decreased by 9% (P < .05) in the latter group. During oral glucose tolerance test (OGTT), the area under the glucose curve (AUCglucose) increased by 17% (P = .05) in the bendrofluazide-treated group but decreased by 19% (P = .05) in the lisinopril group, although there was no difference between the drug effects on AUCinsulin. The LDL/HDL cholesterol ratio increased during bendrofluazide treatment. The serum potassium concentration decreased by 10% (P = .0001) during bendrofluazide treatment but increased by 6% (P = .0001) in the lisinopril-treated group. The change in serum potassium was correlated to the change in initial insulin response and glucose disappearance rate at IVGTT, and inversely correlated to the change in AUCglucose at OGTT. In conclusion, alterations in serum potassium balance may affect the initial insulin release and glucose disposal. Bendrofluazide treatment decreases the serum potassium concentration, reduces the initial insulin release and the glucose disposal, and, in addition, impairs insulin sensitivity. Lisinopril treatment increases serum potassium concentration and the initial insulin response, and decreases AUCglucose, but does not improve insulin sensitivity per se.

Metabolic effects of long-term angiotensin-converting enzyme inhibition with fosinopril in patients with essential hypertension: relationship to angiotensin-converting enzyme inhibition

Fifty patients with mild to moderate essential hypertension were randomized to receive either 20 mg fosinopril daily for 16 weeks or placebo for 4 weeks followed by 12 weeks of 50 mg atenolol daily. Prior to these 16 weeks there was a placebo wash-out period of 2-6 weeks. Blood pressure measurements, euglycaemic, hyperinsulinaemic glucose clamps, and intravenous glucose tolerance tests (IVGTT) were performed at baseline and after 4 and 16 weeks. Blood lipid status was evaluated at baseline and 16 weeks. The insulin sensitivity index (M/I) increased by 12% during the prolonged placebo period, and subsequently decreased by 12% during treatment with atenolol in that group. A post-hoc analysis of covariance indicated that the increase in insulin sensitivity during the initial 4 weeks may have been due to carry-over effects from previous antihypertensive treatment. Fosinopril increased glucose disappearance during IVGTT at 4 and 16 weeks (k values 1.46 and 1.33 vs 1.10 at baseline) but had no effect on insulin sensitivity. The change in insulin sensitivity and serum triglycerides during treatment with fosinopril was related to angiotensin-converting enzyme inhibition in serum. In conclusion, carry-over effects from previous antihypertensive medication were indicated in this study, probably because of an insufficient wash-out period in many patients. Therefore, 4 weeks of placebo wash-out in all patients is advisable in this kind of investigation.

Treatment with a beta-blocker with beta 2-agonism improves glucose and lipid metabolism in essential hypertension

In a randomized double-blind crossover study in 42 patients with essential hypertension, the metabolic effects of a beta-adrenergic blocker with a pronounced beta 2-agonistic effect, dilevalol 400 mg x 1, were compared with those of metoprolol succinate 200 mg x 1. The effects of glucose metabolism were evaluated by the hyperinsulinemic euglycemic clamp technique and an intravenous glucose tolerance test (IVGTT). Insulin-mediated glucose disposal (M) and the insulin sensitivity index (M/I) increased by 19% (P = .011) and 10% (P = .27), respectively, during dilevalol treatment, but decreased by 10% (P = .15) and 22% (P = .0025), respectively, during metoprolol treatment, giving rise to significant differences between the two treatment regimens. Compared with dilevalol-treated patients, those treated with metoprolol showed increased plasma insulin values at the end of the IVGTT, but there was no difference in plasma glucose concentrations or glucose tolerance. Hemoglobin A1c (HbA1c) levels increased by 5.4% (P = .04) in the metoprolol group. Serum cholesterol, total serum and very-low-density lipoprotein (VLDL) triglycerides, and serum urate levels decreased significantly (by 6%, 22%, 29%, and 14%, respectively) during dilevalol treatment, and there was a significant difference between the effects of the two drugs on total, VLDL, and low-density lipoprotein (LDL) triglyceride and serum urate levels. These data demonstrate that a beta-blocker with a partial beta 2-agonist action differs in its metabolic effect profile from a selective beta 1-blocker and may offer advantages by improving glucose and lipid metabolism.