Impairment of glucose tolerance produced by diuretics and other drugs

Former long-term use of combined hormonal contraception and glucose metabolism disorders in perimenopausal women: A prospective, population-based cohort study

INTRODUCTION

Current use of combined hormonal contraceptives worsens glucose tolerance and increases the risk of type 2 diabetes mellitus at late fertile age, but the impact of their former use on the risk of glucose metabolism disorders is still controversial.

MATERIAL AND METHODS

This was a prospective, longitudinal birth cohort study with long-term follow-up consisting of 5889 women. The cohort population has been followed at birth, and at ages of 1, 14, 31 and 46. In total, 3280 (55.7%) women were clinically examined and 2780 also underwent a 2-h oral glucose tolerance test at age 46. Glucose metabolism indices were analyzed in former combined hormonal contraceptive users (n = 1371) and former progestin-only contraceptive users (n = 52) and in women with no history of hormonal contraceptive use (n = 253).

RESULTS

Compared with women with no history of hormonal contraceptive use, those who formerly used combined hormonal contraceptives for over 10 years had an increased risk of prediabetes (odds ratio [OR] 3.9, 95% confidence interval [CI]: 1.6-9.2) but not of type 2 diabetes mellitus. Former progestin-only contraceptive use was not associated with any glucose metabolism disorders. The results persisted after adjusting for socioeconomic status, smoking, alcohol consumption, parity, body mass index and use of cholesterol-lowering medication.

CONCLUSIONS

Former long-term use of combined hormonal contraceptives was associated with a significantly increased risk of prediabetes in perimenopausal women, which potentially indicates a need of screening for glucose metabolism disorders in these women.

Loss of Slc12a2 specifically in pancreatic β-cells drives metabolic syndrome in mice

The risk of type-2 diabetes and cardiovascular disease is higher in subjects with metabolic syndrome, a cluster of clinical conditions characterized by obesity, impaired glucose metabolism, hyperinsulinemia, hyperlipidemia and hypertension. Diuretics are frequently used to treat hypertension in these patients, however, their use has long been associated with poor metabolic outcomes which cannot be fully explained by their diuretic effects. Here, we show that mice lacking the diuretic-sensitive Na+K+2Cl-cotransporter-1 Nkcc1 (Slc12a2) in insulin-secreting β-cells of the pancreatic islet (Nkcc1βKO) have reduced in vitro insulin responses to glucose. This is associated with islet hypoplasia at the expense of fewer and smaller β-cells. Remarkably, Nkcc1βKO mice excessively gain weight and progressive metabolic syndrome when fed a standard chow diet ad libitum. This is characterized by impaired hepatic insulin receptor activation and altered lipid metabolism. Indeed, overweight Nkcc1βKO but not lean mice had fasting and fed hyperglycemia, hypertriglyceridemia and non-alcoholic steatohepatitis. Notably, fasting hyperinsulinemia was detected earlier than hyperglycemia, insulin resistance, glucose intolerance and increased hepatic de novo gluconeogenesis. Therefore, our data provide evidence supporting the novel hypothesis that primary β-cell defects related to Nkcc1-regulated intracellular Cl-homeostasis and β-cell growth can result in the development of metabolic syndrome shedding light into additional potential mechanisms whereby chronic diuretic use may have adverse effects on metabolic homeostasis in susceptible individuals.

Effect of buspirone: An anxiolytic drug on blood glucose in humans

The present study investigated the effect of an antianxiety drug, buspirone on blood glucose and plasma insulin level concerning the role of 5-HT(1A) receptors in blood glucose regulation in healthy humans. Twelve healthy male volunteers were administered single oral doses of buspirone (10 mg) or placebo, in a randomized, crossover way, followed by oral glucose load (75 gm in 200 ml) at reported T(max) i.e. the time of peak plasma concentration of the respective administered drug. The blood samples were collected as predose, postdose and post oral glucose load at 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 hr to investigate the effect of buspirone or placebo at basal blood glucose and plasma insulin level and after oral glucose load induced (postprandial) blood glucose and plasma insulin level. Blood glucose and plasma insulin concentrations were estimated by glucose hexokinase method and enzyme linked immunosorbent assay (ELISA) method respectively. The concentration of blood glucose was significantly (p<0.05) decreased after oral glucose load following administration of buspirone in comparison with placebo however no significant change was observed in the fasting blood glucose and plasma insulin (fasting and oral glucose load induced) level. In conclusions, the present study findings show that buspirone produced a significant alteration in blood glucose level in healthy humans. In addition, study results also indicate that the involvement of serotonergic (5-HT, receptors) mechanism of blood glucose regulation in humans is different from animals.

Enhanced insulin secretion and improved glucose tolerance in mice with homozygous inactivation of the Na(+)K(+)2Cl(-) co-transporter 1

The intracellular chloride concentration ([Cl(-)](i)) in β-cells plays an important role in glucose-stimulated plasma membrane depolarisation and insulin secretion. [Cl(-)](i) is maintained above equilibrium in β-cells by the action of Cl(-) co-transporters of the solute carrier family 12 group A (Slc12a). β-Cells express Slc12a1 and Slc12a2, which are known as the bumetanide (BTD)-sensitive Na(+)-dependent K(+)2Cl(-) co-transporters 2 and 1 respectively. We show that mice lacking functional alleles of the Slc12a2 gene exhibit better fasting glycaemia, increased insulin secretion in response to glucose, and improved glucose tolerance when compared with wild-type (WT). This phenomenon correlated with increased sensitivity of β-cells to glucose in vitro and with increased β-cell mass. Further, administration of low doses of BTD to mice deficient in Slc12a2 worsened their glucose tolerance, and low concentrations of BTD directly inhibited glucose-stimulated insulin secretion from β-cells deficient in Slc12a2 but expressing intact Slc12a1 genes. Together, our results suggest for the first time that the Slc12a2 gene is not necessary for insulin secretion and that its absence increases β-cell secretory capacity. Further, impairment of insulin secretion with BTD in vivo and in vitro in islets lacking Slc12a2 genes unmasks a potential new role for Slc12a1 in β-cell physiology.

Glucose-induced electrical activity in rat pancreatic beta-cells: dependence on intracellular chloride concentration

A rise in glucose concentration depolarizes the beta-cell membrane potential leading to electrical activity and insulin release. It is generally believed that closure of KATP channels underlies the depolarizing action of glucose, though work from several laboratories has indicated the existence of an additional anionic mechanism. It has been proposed that glucose activates a volume-regulated anion channel, generating an inward current due to Cl- efflux. This mechanism requires that intracellular [Cl-] is maintained above its electrochemical equilibrium. This hypothesis was tested in rat beta-cells by varying [Cl-] in the patch pipette solution using the Cl--permeable antibiotic amphotericin B to allow Cl- equilibration with the cell interior. Under such conditions, a depolarization and electrical activity could be evoked by 16 mM glucose with pipette solutions containing 80 or 150 mM Cl-. At 40 or 20 mM Cl-, a subthreshold depolarization was usually observed, whilst further reduction to 12 or 6 mM abolished depolarization, in some cases leading to a glucose-induced hyperpolarization. With a pipette solution containing gramicidin, which forms Cl--impermeable pores, glucose induced a depolarization and electrical activity irrespective of [Cl-] in the pipette solution. Under the latter conditions, glucose-induced electrical activity was prevented by bumetanide, an inhibitor of the Na+-K+-2Cl- co-transporter. This inhibition could be overcome by the use of amphotericin B with a high [Cl-] pipette solution. These findings suggest that the maintenance of high intracellular [Cl-] in the beta-cell is an important determinant in glucose-induced depolarization, and support the hypothesis that beta-cell stimulation by glucose involves activation of the volume-regulated anion channel and generation of an inward Cl- current.

Combined oral contraceptives in the treatment of polycystic ovary syndrome

Combined oral contraceptives (COC) are the most often used treatment modality for polycystic ovary syndrome (PCOS). Undisputedly, COC suppress androgen production, thus ameliorating skin androgenic symptoms and improving menstrual dysfunction. On the other hand, there are still many unresolved issues concerning their metabolic effects. COC could decrease insulin sensitivity and deteriorate glucose tolerance, although the negative influence on insulin sensitivity is dependent on other factors (especially obesity) and this need not be expressed in non-obese patients. It is probable that the impairment of glucose tolerance is reversible, as the incidence of diabetes is not increased in past COC users. The effects of COC on the lipid spectrum are dependent on the type of gestagen, but lipid levels usually remain within the reference limits. Combination therapy of COC with weight reduction or insulin sensitizers could further suppress androgen levels and improve metabolic parameters. The establishment of COC after laparoscopic ovarian drilling may further decrease androgen levels. The combination of COC and GnRH analogues is not superior to COC therapy alone. Prospective data about the influence of COC on the risk of diabetes mellitus, coronary artery disease and endometrial cancer in PCOS women are lacking.

Diuretic-related side effects: development and treatment

Diuretics are important therapeutic tools. First, they effectively reduce blood pressure and have been shown in numerous hypertension clinical trials to reduce both cardiovascular and cerebrovascular morbidity and mortality. In addition, their use has been equally effective in controlling cardiovascular events as angiotensin-converting enzyme inhibitors or calcium channel blockers. Diuretics are currently recommended by the Seventh Report of the Joint National Commission on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure report as first-line therapy for the treatment of hypertension. In addition, they remain an important aspect of congestive heart failure treatment in that they improve the congestive symptomatology, which typifies the more advanced stages of congestive heart failure. This article reviews the commonly encountered side effects with the various diuretic classes. Where indicated, the mechanistic basis and treatment of such side effects is further discussed.

Adverse Prognostic Significance of New Diabetes in Treated Hypertensive Subjects

Diabetes may develop in nondiabetic hypertensive subjects during treatment, but the long-term cardiovascular implications of this phenomenon are not clear. We determined the prognostic value of new diabetes in hypertensive subjects. In a long-term cohort study, 795 initially untreated hypertensive subjects, 6.5% of whom with type 2 diabetes, underwent diagnostic procedures including 24-hour ambulatory blood pressure (BP) monitoring and electrocardiography (ECG). Procedures were repeated after a median of 3.1 years in the absence of cardiovascular events. Follow-up duration was 1 to 16 years (median 6.0). New diabetes occurred in 5.8% of subjects initially without diabetes. Antihypertensive treatment included a diuretic in 53.5% of these subjects, versus 30.4% of those in whom diabetes did not develop (P=0.002). Plasma glucose at entry (P=0.0001) and diuretic treatment on follow-up (P=0.004) were independent predictors of new diabetes. Subsequent to the follow-up visit, a first cardiovascular event occurred in 63 subjects. Event rate in nondiabetic subjects at both visits, new diabetes, and diabetes at entry were 0.97, 3.90, and 4.70x100 person-years, respectively (P=0.0001). After adjustment for several confounders, including 24-hour ambulatory BP, the relative risk of events was 2.92 (95% CI: 1.33 to 6.41; P=0.007) in the group with new diabetes and 3.57 (95% CI: 1.65 to 7.73; P=0.001) in the group with previous diabetes, when compared with the group persistently free of diabetes. In treated hypertensive subjects, occurrence of new diabetes portends a risk for subsequent cardiovascular disease that is not dissimilar from that of previously known diabetes.

Diuretics in the treatment of patients who present congestive heart failure and hypertension

The main operational objective of diuretic therapy in patients who present congestive heart failure and hypertension is to reduce or to suppress excess bodily fluid. Effective diuretic therapy decreases cardiac size when the heart is dilated, and it reduces lung congestion and excess water. Consequently, external respiratory work diminishes and cardiac output would be redistributed in favour of systemic vascular beds other than that of the respiratory muscles; dyspnoea decreases markedly and there is a slight reduction in fatigue. This clinical improvement and the fall in body weight caused by diuretics entail an increase in effort capacity. Subsequent exercise training ameliorates the abnormal ventilatory response to physical effort and the skeletal muscle myopathy that occur in heart failure, and thereby it attenuates dyspnoea and decreases fatigue further. Loop and/or thiazide-type diuretics may be used to augment natriuresis in patients with congestive heart failure and hypertension. The state of renal function, the existence of certain co-morbid conditions, potential untoward drug actions, and possible interactions of diuretics with nutrients and with other drugs are some of the factors that must be considered at the time of deciding on the diuretic drug(s) and dose(s) to be prescribed. Spironolactone has been found to increase life expectancy and to reduce hospitalisation frequency when added to the conventional therapeutic regimen of patients with advanced congestive heart failure and systolic dysfunction. Therefore, spironolactone should be the drug of choice to oppose the kaliuretic effect of a loop or of a thiazide-type diuretic.

Occlusive vascular diseases in oral contraceptive users. Epidemiology, pathology and mechanisms

Despite being an unprecedented departure from normal physiology, the combined oral contraceptive is not only highly effective, but it also has a remarkably good safety record. Concerns over safety persist, though, particularly with regard to venous thromboembolism (VTE), stroke and myocardial infarction (MI). Epidemiological studies consistently show an increase in risk of VTE, but the results are more contentious with regard to arterial diseases. Despite 40 years of research, the mechanisms behind these adverse effects are not understood. In this review, we integrate information from published studies of the epidemiology and pathology of the occlusive vascular diseases and their risk factors to identify likely explanations for pathogenesis in oral contraceptive users. Oral contraceptives induce both prothrombotic and fibrinolytic changes in haemostatic factors and an imbalance in haemostasis is likely to be important in oral contraceptive-induced VTE. The complexity of the changes involved and the difficulty of ascribing clinical significance has meant that uncertainty persists. A seriously under-researched area concerns vascular changes in oral contraceptive users. Histologically, endothelial and intimal proliferation have been identified in women exposed to high plasma estrogen concentrations and these lesions are associated with thrombotic occlusion. Other structural changes may result in increased vascular permeability, loss of vascular tone and venous stasis. With regard to arterial disease risk, epidemiological information relating to dose effects and joint effects with other risk factors, and studies of pathology and changes in risk factors, suggests that oral contraceptive use per se does not cause arterial disease. It can, nevertheless, synergise very powerfully with subclinical endothelial damage to promote arterial occlusion. Accordingly, the prothrombotic effects of the oral contraceptive estrogen intervene in a cycle of endothelial damage and repair which would otherwise remain clinically silent or would ultimately progress - in, for example, the presence of cigarette smoking or hypertension - to atherosclerosis. Future work in this area should focus on modification of the effects of established risk factors by oral contraceptive use rather than modification of the supposed risk of oral contraceptive use by established risk factors. Attempts to understand vascular occlusion in oral contraceptive users in terms of the general features of VTE or with reference to atherosclerosis may be limiting, and future work needs to acknowledge that such occlusions may have unique features. Unequivocal identification of the mechanisms involved would contribute considerably to the alleviation of fears over vascular disease and to the development of even safer formulations.

Proteinuria is an independent risk factor for ischemic stroke in non-insulin-dependent diabetes mellitus

BACKGROUND AND PURPOSE

Proteinuria is an independent risk factor for cardiovascular disease in patients with NIDDM. The aim of this study was to assess the relationship between proteinuria and ischemic stroke in subjects with NIDDM, and to determine whether proteinuria is an independent risk factor for stroke.

METHODS

We performed a case-control study of 59 diabetic patients with first-ever ischemic stroke due to thrombotic arterial occlusion, who were considered cases, and 180 diabetic patients without stroke, matched by gender, age, and diabetes duration, as a control group. WHO criteria for verified definite or possible stroke were used to ascertain the diagnosis of stroke. For the purpose of this study proteinuria was defined as a 24-hour urinary protein excretion rate of >/=20 and <200 microg/min. Risk factors included were smoking, blood pressure, body mass index, serum total cholesterol, hyperglycemia, and proteinuria.

RESULTS

Subjects with stroke had higher proteinuria proportion and systolic and diastolic blood pressures. Both frequency of antihypertensive treatment and antihypertensive drugs used were similar among subjects with and without stroke. In multivariate logistic regression analysis, the ORs and 95% CIs for the variables identified as risk factors for stroke were as follows: systolic pressure (OR 3.10; 95% CI 3.01 to 4.21; P=0.03); diastolic pressure (OR 3.30; 95% CI 1.04 to 4.48; P<0.0001); fasting glucose >/=11.1 mmol (OR 1.82; 905% CI 1.4 to 3.8; P=0.04), HbA1c >/=9.5% (OR 1.7; 95% CI 1.3 to 5.1; P<0.01), and proteinuria (OR 3.23; 95% CI 1.06 to 4.36; P<0.0001).

CONCLUSIONS

Our case-control study gives evidence that proteinuria is an independent risk factor for ischemic stroke in patients with NIDDM.

Diabetes and cardiovascular events in hypertensive patients

To determine the relation of self-reported history of diabetes as well as baseline and in-treatment blood sugar to subsequent cardiovascular disease (CVD) in treated hypertensive patients, we assessed the experience of 6886 participants in a systematic treatment program. The presence or absence of a history of diabetes was known for all patients, who were then stratified into 3 groups according to blood sugar at baseline and in treatment (<6.11, 6.11 to 7.74, and >/=7.75 mmol/L). Some 7.4% of all patients reported history of diabetes, and the overall prevalence of blood sugar >/=7. 75 mmol/L was 7.7% and 10.4% at baseline and in treatment, respectively. Patients with a history of diabetes were 10 or 8 times as likely to have blood sugar >/=7.75 mmol/L at baseline (47.2% versus 4.5%) or in treatment (55.0% versus 6.8%), as were patients without history. During an average 6.3 years of follow-up, patients with history of diabetes had a cardiovascular event incidence 2-fold higher than those without history (20.8 versus 8.6/1000 person-years). Age-gender-adjusted CVD incidence rate but not non-CVD was twice as high in the highest compared with the lowest blood sugar stratum (baseline 16.6 versus 8.4/1000 person-years; in treatment 15.2 versus 8.2). Three separate models of Cox multivariate analysis revealed that history of diabetes (with no history as reference) had a greater association with CVD events (hazard ratio 2.37, 95% confidence interval 1.80 to 3.11) than did baseline (1.75, 1.31 to 2.33) or in-treatment blood sugar (1.55, 1. 19 to 2.02). Furthermore, in the presence of history of diabetes (2. 15, 1.58 to 2.92), neither baseline nor in-treatment blood sugar was independently associated with CVD risk. In the elevated (>/=7.75 mmol/L) in-treatment blood sugar group, the age-gender-adjusted rate of CVD events in frequent diuretic users (30.79/1000 person-years) was significantly higher than in moderate (13.34, P=0.004) and rare users (13.25, P=0.008). These data affirm that the coincidence of diabetes and hypertension is common, that evidence of diabetes substantially increases CVD risk, that self-reported history is a more powerful predictor of CVD events than any measure of blood sugar, and that CVD increases in hypertensive diuretic users who develop hyperglycemia even when blood pressure is well controlled.

Diabetes mellitus as a risk factor for death from stroke. Prospective study of the middle-aged Finnish population

BACKGROUND AND PURPOSE

High blood pressure is the most important risk factor for stroke. It is also known that diabetic patients are at increased risk of both hypertension and stroke. The aim of this study was to assess the independent effect of diabetes as a risk factor for stroke. Results from the previous studies of this question have been somewhat inconclusive.

METHODS

We performed a prospective study (average follow-up, 16.4 years) of 8077 men and 8572 women who had participated in risk factor surveys in Eastern Finland in 1972 (20 years of follow-up) and 1977 (15 years of follow-up). Risk factors included in the current analyses were smoking, blood pressure, antihypertensive drug treatment, serum total cholesterol, and diabetes either at baseline or developed during the follow-up. Age- and risk factor-adjusted relative risks for death of stroke were determined with the Cox proportional hazards model.

RESULTS

Diabetes mellitus was the strongest risk factor for death from stroke among both men and women in univariate and multivariate analyses. In addition, smoking and systolic blood pressure appeared to be independent risk factors among both sexes, as did serum total cholesterol among men. Men with diabetes at baseline appeared to be at a sixfold increased risk of death from stroke, while relative risk for men who developed diabetes during the follow-up was 1.7. In women, those who were diabetic at baseline were at higher risk of stroke than women who developed diabetes later (relative risks, 8.2 and 3.7, respectively). Of stroke deaths, 16% in men and 33% in women were attributed to diabetes.

CONCLUSIONS

Diabetic subjects have a very high risk of death from stroke, particularly women. Our data also suggest that the duration of diabetes is an important factor contributing to the risk of stroke.

Glucose and cholesterol elevations during thiazide therapy: intention-to-treat versus actual on-therapy experience

PURPOSE

This nonrandomized, parallel-group, prospective clinical series in consecutive patients was conducted to determine if the method of analysis of biochemical data collected in long-term treatment trials can explain the controversy regarding the effects of thiazides on plasma glucose or cholesterol.

PATIENTS AND METHODS

Fasting serum glucose, potassium, and cholesterol levels were determined before therapy, and yearly thereafter (4.0 +/- 0.1 years) in 634 consecutive patients treated for more than 1 year with antihypertensive monotherapy.

RESULTS

When the data were analyzed by the intention-to-treat paradigm (ignoring changes in therapy), glucose and cholesterol levels in the thiazide group were significantly higher (compared to baseline or to the other therapy group) only at year 1. When the data were analyzed by actual on-therapy experience (censoring patients when therapy is altered)--a more traditional way to examine side effects--these differences were significant for all 5 years studied. Even if as few as 8% of patients who changed therapies were included in an intention-to-treat analysis, these differences became nonsignificant.

CONCLUSION

These comparisons not only indicate why a dichotomy might exist between clinical practice (analyzed by actual on-therapy experience) and randomized trials (analyzed by intention-to-treat methods), regarding biochemical changes in glucose and cholesterol during thiazide therapy, but also that, for secondary hypotheses, analyzing data by both methods of assignment is important.

Risk factors for non-insulin-dependent diabetes mellitus requiring treatment in the elderly

OBJECTIVE

To examine the relationship of possible modifiable risk factors, including obesity, physical activity level, alcohol consumption, blood pressure, and thiazide diuretic use with the development of non-insulin-dependent diabetes mellitus (NIDDM) requiring treatment among a large cohort of community-dwelling elderly.

SETTING

The East Boston Senior Health Project, one of four components of the National Institute on Aging-sponsored Established Populations for the Epidemiologic Study of the Elderly (EPESE).

PARTICIPANTS

Residents of East Boston who were 65 years of age or older.

MEASUREMENTS

We performed a prospective cohort study with follow-up over two consecutive 3-year time periods beginning in 1982-1983. The main outcome measure was the occurrence of NIDDM, defined as new treatment with a hypoglycemic agent. A total of 2737 study participants contributed 4682 3-year intervals for analysis.

MAIN RESULTS

NIDDM requiring hypoglycemic therapy occurred in 185 participants over the duration of the study. High body mass index (> 26 kg/m2) (adjusted odds ratio 2.4, 95% confidence interval 1.3-4.4) and low physical activity level (adjusted odds ratio 1.5, 95% confidence interval 1.0-2.1) were significant predictors of NIDDM in a multiple logistic regression model adjusting for age, sex, blood pressure, and self-report of "high blood sugar" moderate alcohol consumption (0.5-<1 ounce per day) had an inverse relation to NIDDM of borderline significance (adjusted odds ratio 0.4, 95% confidence interval 0.2-1.0). Those receiving one or more non-thiazide antihypertensive agents had a higher risk of developing NIDDM in a model including age, sex, body mass index, various antihypertensive regimens, physical activity level, alcohol consumption, blood pressure, and self-report of "high blood sugar." Thiazide diuretic therapy alone or in combination with another antihypertensive was not associated with NIDDM.

CONCLUSIONS

Our findings suggest a positive relationship of obesity and low physical activity level with the development of NIDDM requiring treatment in elderly persons. The inverse association of borderline significance between moderate alcohol use and NIDDM deserves further study. Thiazide diuretic therapy conferred no excess risk for developing NIDDM in this older population although selection factors in the choice of antihypertensive therapy may partially explain the absence of a thiazide effect.

Update on the metabolic effects of steroidal contraceptives and their relationship to cardiovascular disease risk

Evaluation of metabolic disturbances has had an important role in the modification of oral contraceptive formulations toward estrogen-progestin combinations with reduced adverse metabolic impact. An increasing number of interrelationships between metabolic risk factors for cardiovascular disease are being recognized, and a metabolic syndrome of disturbances has been identified with insulin resistance as a potential underlying factor. The insulin resistance syndrome includes hyperinsulinemia and impaired glucose tolerance, hypertriglyceridemia, reduced high-density lipoprotein concentrations, and hypertension. Increased concentration of a small, dense, low-density lipoprotein subtype may also be important. Depending on steroid type and dose, combined oral contraceptives may induce all the features of the insulin resistance syndrome. Reduction in estrogen dose and modification of progestin content have resulted in formulations with no adverse effect on high-density lipoprotein and blood pressure, but insulin resistance and hypertriglyceridemia remain. These are caused primarily by the estrogen component. Therefore modification of the estrogen content of oral contraceptives might result in "metabolically transparent" formulations that could conceivably afford a degree of cardiovascular protection.

Inhibition by hydrochlorothiazide of insulin release and calcium influx in mouse pancreatic beta-cells

1. The effect of hydrochlorothiazide on insulin release, 36Cl- fluxes and 45Ca2+ uptake was tested in beta-cell-rich mouse pancreatic islets. 2. At high glucose concentrations (10 and 20 mmol l-1), low concentrations of hydrochlorothiazide (0.1-1.0 mumol l-1) reduced insulin release by 22-42%. At lower glucose concentrations (3-8.5 mmol l-1) insulin release was not affected by the drug. 3. Neither short-term influx (3 min) nor net accumulation (60 min) of 36Cl- in the islets was affected by hydrochlorothiazide (0.1-500 mumol l-1). 4. Glucose-stimulated 45Ca2+ uptake was significantly reduced by hydrochlorothiazide (1-10 mumol l-1). 5. The data suggest that the diabetogenic effect of hydrochlorothiazide, at least in part, can be mediated by direct inhibition of insulin release from the pancreatic beta-cells. The inhibition is not mediated by reduced chloride fluxes but may rather be caused by inhibition of calcium uptake.

The effects of various antihypertensive agents on cardiovascular risk factors in patients with renal failure

Systemic cardiovascular diseases are the most important cause of morbidity and mortality among patients with chronic renal failure. Hypertension, lipid-profile abnormalities, glucose intolerance, and left ventricular hypertrophy are found in most patients with chronic renal failure and are responsible for the increased incidence of atherosclerosis. Hypertension is the risk factor most susceptible to treatment, but consideration must be given in selecting an antihypertensive agent not only to its effect on blood pressure but to its effects on the other risk factors. Improper selection could impair the long-term benefit of good blood pressure control by increasing the severity of the other cardiovascular risk factors and eventually worsening the prognosis of the chronic renal failure. The remaining renal function in patients not yet in end-stage renal failure deserves special consideration; an adequate antihypertensive regimen could potentially delay the need for dialysis.

Furosemide treatment causes age-dependent glucose intolerance and islet damage in obese-hyperglycaemic mice

The effects of furosemide on fasting serum glucose, glucose tolerance and pancreatic islet morphology were studied in ob/ob mice of two age groups, 3 months and 8 months. A single dose of furosemide (200 mg/kg body weight) induced acute hyperglycaemia in the young (3 months) as well as the old (8 months) ob/ob mice. Two days after the furosemide injection the glucose tolerance was markedly impaired in older animals, whereas it was normal in younger animals. Glucose tolerance in old mice varied markedly between individuals and showed two patterns. Thus, in one group of 8 months old mice, fasting serum glucose was elevated and glucose tolerance was very poor, whereas in the other group it was at least as good as in the saline-injected controls. Histological analysis showed normal islet morphology in furosemide-treatment young mice but an inflammatory reaction in islets from furosemide-injected old animals. A significant correlation between the degree of islet abnormality and glucose tolerance was observed. The data suggest that susceptibility to develop furosemide-induced long-term glucose intolerance is associated with the development of the obese-hyperglycaemic syndrome rather than being linked to the inheritance of the ob/ob genome as such.

Effects of antihypertensive agents on coronary artery disease risk factors

The adverse effects of certain antihypertensive medications, most notably diuretics and beta blockers, on serum lipids, glucose, and potassium may explain why control of hypertension has not been accompanied by declines in coronary artery disease. Evidence indicates that angiotensin-converting enzyme (ACE) inhibitors, including quinapril, the newest member of this class of drugs, have no deleterious effects on these coronary risk factors. In addition to differences in chemical structure, the unique activity of quinapril at the local tissue level might to some degree explain its comparatively favorable clinical profile. Consequently, ACE inhibiting agents may be better choices for the management of patients with mild-to-moderately elevated blood pressure. However, controlled clinical trials with these drugs are needed to determine their impact on events related to coronary artery disease.

A comparative study of oral glucose tolerance tests in Nigerian women on three types of steroidal contraceptives

Oral glucose tolerance tests (OGTT) were performed on 146 Nigerian women volunteers using one of three types of steroidal contraceptives: high-dose combined pills; low-dose combined pills and injectable progesterone. Twenty-six appropriately matched nonusers served as controls. The OGTT curves were analysed using the H-index (HI). Women on injectable progesterone and high-dose combined pills, respectively, had significantly higher (P less than 0.05) mean HI than the controls. The low-dose combined pills had the least effect on carbohydrate metabolism.

An open prospective study on the effects on carbohydrate metabolism of an oral monophasic contraceptive containing gestodene (WL-70)

The effects of a monophasic oral contraceptive (gestodene 75mcg + ethinylestradiol 30 mcg) on plasma glucose (PG) and insulin (IRI) responses to an oral glucose load (OGTT) and on glycosylated haemoglobin Alc (HbAlc), fructosamine (Fr), total cortisol (FT) and transcortin (CBG) were studied in 30 healthy women. Blood samples were taken before treatment and after 6 and 12 cycles. After 6 and 12 months, OGTT-PG and IRI levels showed substantially unchanged values; for HbAlc and Fr the same behaviour was seen with the exception of the latter between 6 and 12 months; FT and CBG showed significant rises. All recorded values were in the normal range. The basal and dynamic PG and IRI behaviour failed to show any significant variations between pre-treatment values and those after 6 and 12 months of OC administration. Other data showed a substantial neutrality for this oral contraceptive containing gestodene.

ACE-inhibition increases hepatic and extrahepatic sensitivity to insulin in patients with type 2 (non-insulin-dependent) diabetes mellitus and arterial hypertension

To assess the effects of ACE-inhibition on insulin action in Type 2 (non-insulin-dependent) diabetes mellitus associated with essential hypertension, 12 patients with Type 2 diabetes (on diet and oral hypoglycaemic agents) and arterial hypertension were examined on two occasions, in a single blind, cross-over study after two days of treatment with either captopril or a placebo. The study consisted of a euglycaemic-hyperinsulinaemic clamp (two sequential steps of insulin infusion at the rates of 0.25 mU.kg-1.min-1 and 1 mU.kg-1.min-1, 2 h each step), combined with an infusion of 3-3H-glucose to measure the rate of hepatic glucose production and that of peripheral glucose utilization. The results show that blood pressure was lower after captopril (sitting, systolic 148 +/- 5 mm Hg, diastolic 89 +/- 2 mm Hg) compared to placebo (155 +/- 6 and 94 +/- 2 mm Hg) (p less than 0.05). Captopril treatment resulted in a more suppressed hepatic glucose production (2.7 +/- 0.4 vs 4.94 +/- 0.55 mumol.kg-1.min-1), and a lower plasma non-esterified fatty acid concentration (0.143 +/- 0.05 vs 0.200 +/- 0.05 mmol/l) (captopril vs placebo, p less than 0.05) at the end of the first step of insulin infusion (estimated portal plasma insulin concentration 305 +/- 28 pmol/l); and in a greater glucose utilization (36.5 +/- 5.1 vs 28 +/- 3.6 mumol.kg-1.min-1, p less than 0.001) at the end of the second step of insulin infusion (arterial plasma insulin concentration of 604 +/- 33 pmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Low-dose oral contraceptives and carbohydrate metabolism

Combined oral contraceptive use has been associated with increased incidence of impaired and diabetic glucose tolerance. Although increased risk of overt symptoms of diabetes has not been associated with oral contraceptive use, increased risk of coronary heart disease has been consistently demonstrated. Diabetes is associated with increased risk of coronary heart disease, especially in women. Elevated plasma glucose and insulin concentrations are also associated with increased risk of coronary heart disease. Studies of the effects of low-dose oral contraceptives on glucose tolerance test plasma glucose and insulin levels are reviewed. Low-dose combined oral contraceptives induced changes in measures of carbohydrate metabolism in directions consistent with increased risk of coronary heart disease. The magnitude of these changes may depend on the dose and type of progestogen. The clinical implications of these changes are unknown, but it would seem advisable to minimize them where possible.

Effects of sulfonamides on a metabolite-regulated ATPi-sensitive K+ channel in rat pancreatic B-cells

Intracellular ATP (ATPi)-sensitive K+ [K+(ATP)] channels are now a recognized site of action of clinically useful hypoglycemic and hyperglycemic sulfonamides. We have further examined the action of these agents on single K+ channels in rat pancreatic B-cells 1) Tolbutamide and glyburide, two hypoglycemic sulfonylureas which decrease K+(ATP) channel activity in the cell-attached patch, affect the kinetics of K+(ATP) channel in a manner similar to glucose. They shorten the duration of the "burst," or cluster of open channel events, while lengthening the intervals between bursts. 2) The hyperglycemic vasodilator diazoxide increases mean K+(ATP) channel activity in the cell-attached patch as well as in the inside-out excised patch exposed to ATPi. It appears to lengthen channel bursts and shorten the intervals between them. Two structurally similar diuretics, hydrochlorothiazide and furosemide, which have mild hyperglycemic effects, do not increase K+(ATP) channel activity even at clinically toxic concentrations. 3) Neither the sulfonylureas nor diazoxide directly affect the activity of single delayed rectifier K+ channels or single calcium and voltage-activated K+ channels in normal B-cells.

Low and conventional dose cyclopenthiazide on glucose and lipid metabolism in mild hypertension

In a double-blind, placebo controlled, randomised parallel study we investigated the antihypertensive activity and metabolic adverse effects of three doses of cyclopenthiazide in 53 patients with mild hypertension. After a 4 week placebo washout period, patients with diastolic blood pressures between 90-110 mm Hg were randomly assigned to receive 50 micrograms, 125 micrograms and 500 micrograms of cyclopenthiazide or matching placebo, over an 8 week active treatment period. Blood pressure was recorded at 2 weekly intervals during the trial. Venous samples were taken for evaluation of drug effect on indices of carbohydrate and lipid metabolism just prior to, and on completion of, the active treatment period. Systolic and diastolic blood pressure decreased significantly (P less than 0.05) with the 125 micrograms and 500 micrograms doses of cyclopenthiazide. No change was apparent in any index of glucose and lipid metabolism over time. Low and conventional doses of cyclopenthiazide lower blood pressure without alteration to the metabolic profile in the short term.

Furosemide reduces insulin release by inhibition of Cl- and Ca2+ fluxes in beta-cells

The effect of furosemide on insulin release, glucose oxidation, 36Cl- fluxes, and 45Ca2+ uptake was studied in isolated, beta-cell-rich pancreatic islets from ob/ob mice. Low concentrations of furosemide (0.01-0.1 mM) reduced the glucose-induced insulin release, whereas high doses (1-10 mM) increased basal and glucose-induced release. Furosemide at concentrations that reduced glucose-induced insulin release (0.01-0.1 mM) did not affect the islet production of 14CO2 from D-[U-14C]glucose. The influx rate and equilibrium content of 36Cl- were reduced by furosemide, whereas the basal and glucose-stimulated 36Cl- efflux rates were unaffected. The glucose-induced (10 mM) uptake of 45Ca2+ was inhibited by furosemide. It is suggested that the diabetogenic action of furosemide may be due, at least in part, to direct inhibition of insulin release from the pancreatic beta-cells. This may be caused primarily by inhibition of an inwardly directed Cl- pump, leading to a reduced transmembrane electrochemical gradient for chloride in the beta-cells. This reduced gradient in combination with unaltered Cl- permeability may lead to decreased total outward Cl- transport, a factor associated with stimulated calcium uptake and insulin release.

The role of hyperinsulinemia in the pathogenesis of ovarian hyperandrogenism

The evidence that supports the hypothesis that insulin and LH both regulate ovarian androgen production was presented. The most dramatic clinical example of the association between hyperinsulinemia and hyperandrogenism is the HAIR-AN syndrome. Our hypothesis is that, in the HAIR-AN syndrome, the severe insulin resistance causes a compensatory hyperinsulinemia, which stimulates ovarian androgen production if adequate LH is present. The acanthosis nigricans is an epiphenomenon of the syndrome. Acanthosis nigricans is a dermatologic manifestation of severe insulin resistance. In vitro evidence suggests that insulin and IGF-I stimulate androgen production in incubations of human stroma and theca. The stromatropic effects of insulin may sensitize the stroma to the stimulatory effects of LH. In some hyperandrogenic-insulin-resistant women, a glucose load appears to produce an acute rise in circulating androgens. The magnitude of the rise in circulating androgens is proportional to the magnitude of the insulin response to the glucose load. These data suggest that hyperinsulinemia may play a central role in the development of ovarian hyperandrogenism.

Evidence for diabetogenic action of bumetanide in mice

The effect of bumetanide on carbohydrate metabolism was studied in mice. Intraperitoneal injection of 50 or 100 mg bumetanide/kg body weight resulted in an acute and transient hyperglycaemia. Pretreatment with 240 mg probenecid/kg body weight reduced the diuretic effect but potentiated the hyperglycaemic effect of bumetanide (50 mg/kg body weight). The glucose tolerance was impaired, and there was an elevated serum glucose and glucose/insulin ratio 2 h after a single injection of bumetanide (100 mg/kg body weight). It is suggested that bumetanide has an acute effect on carbohydrate metabolism in mice that is not secondary to diuresis and that the reduced glucose tolerance may, at least in part, be due to a reduced capacity to secrete insulin.

Furosemide-induced glucose intolerance in mice is associated with reduced insulin secretion

The effect of furosemide on carbohydrate metabolism was studied in ob/ob mice. Intraperitoneal injection of a single dose of furosemide (200 mg/kg body weight) into fasted mice resulted in acute hyperglycaemia and two days after such a single dose, the mice showed fasting hyperglycaemia and glucose intolerance. Pancreatic islets from mice that had been injected with furosemide (200 mg/kg body weight) two days prior to the in vitro experiments showed increased basal (3 mmol/1 D-glucose) and decreased glucose-stimulated (20 mmol/1) insulin release. Islets from furosemide- or saline-injected animals showed no difference in islet insulin content. The results show that furosemide has both acute and long-term effects on carbohydrate metabolism in ob/ob mice. It is suggested that this, at least in part, is due to an effect on the pancreatic beta-cells.

Furosemide causes acute and long-term hyperglycaemia and reduces glucose tolerance in mice

The effect of furosemide on carbohydrate metabolism was studied in mice. Single-dose administration (200 mg kg-1 body weight) resulted in transient hyperglycaemia and a rise in the glucose/insulin ratio within 60 min. The glucose tolerance was impaired with elevated serum glucose and reduced insulin response 2 h after the furosemide injection, but had recovered within 24 h. In mice made hypoglycaemic by prior injection of insulin, the basal serum glucose and the glucose tolerance were impaired 22 h after the injection of furosemide. It is suggested that furosemide has both acute and long-term effects on carbohydrate metabolism in mice and that, at least in part, this is due to reduced insulin secretion. Glucose may protect against the diabetogenic action of furosemide.

Hyperglycemic effects of hydrochlorothiazide and propranolol. A biochemical and ultrastructural study

The authors studied the glycemic disturbances provoked by two antihypertensive drugs, propranolol and hydrochlorothiazide, administered alone or in combination to normal and diabetic rats, using biochemical and ultrastructural parameters. It was found that hydrochlorothiazide raised fasting glucose concentration significantly; propranolol alone caused an insignificant rise of glucose, but significantly aggravated the effect of hydrochlorothiazide with an additive interaction. The ultrastructural findings, as well as the urinary C-peptide excretion, confirmed that the glycemic effects should not be thought to be due to a direct action of the drugs used on the endocrine pancreas.

Probenecid potentiates the hyperglycaemic effect but reduces the diuretic effect of frusemide in mice

The effect of probenecid on frusemide-induced diuresis and hyperglycaemia was studied in mice. Probenecid, a known inhibitor of tubular secretion of organic anions in the kidney, strongly reduced the diuretic response to frusemide (25 or 200 mg kg-1 body weight). This effect of probenecid appeared to be dose-dependent up to 240 mg kg-1 body weight, at least at the lower concentration of frusemide. Pretreatment with probenecid (240 mg kg-1 body weight) potentiated the hyperglycaemic effect of frusemide (25 or 200 mg kg-1 body weight). The results show that probenecid has opposite effects on frusemide-induced diuresis and hyperglycaemia in mice. It is suggested that the acute hyperglycaemic effect of frusemide is not directly linked to diuresis.

Triphasic oral contraception: metabolic effects in normal women and those with previous gestational diabetes

The effect of a low-dose triphasic oral contraceptive (ethinyl estradiol and levonorgestrel) on glucose tolerance, plasma insulin and glucagon responses to glucose, fasting plasma cortisol, triglycerides, free fatty acids, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very--low-density lipoprotein cholesterol was investigated in 16 women with previous gestational diabetes and in 19 normal women. Investigations were performed prior to the hormonal intake and after treatment for 2 and 6 months. Before treatment, the women with previous gestational diabetes had significantly elevated fasting glucose (p less than 0.05) and impaired glucose tolerance (p less than 0.05) when compared to those of the healthy control subjects. The glucose, insulin, and glucagon responses to oral glucose remained unchanged during the treatment period. Plasma cortisol increased in both groups (p less than 0.05) whereas plasma triglycerides increased in the control subjects only (p less than 0.05). Plasma free fatty acids, lipoproteins, and high-density lipoprotein cholesterol/total cholesterol ratio remained unchanged in both groups. The results suggest that a low-dose triphasic oral contraceptive (ethinyl estradiol and levonorgestrel) is suitable as contraception even in women with a previous deterioration of glucose tolerance during pregnancy.

Aggravation by propranolol of hyperglycaemic effect of hydrochlorothiazide in type II diabetics without alteration of insulin secretion

14 hypertensive men with type II diabetes sequentially received, in random order, hydrochlorothiazide 50 mg twice a day, propranolol 80 mg twice a day, and both drugs in combination. The 3-week treatment periods were separated by a 1-week washout period. Hydrochlorothiazide significantly increased fasting glucose by 31% (p less than 0.05) and glycosylated haemoglobin (HbA1c) by 6.0% (p less than 0.10). A similar treatment period of propranolol 80 mg twice a day caused no significant increases. However, when both drugs were taken in combination, fasting glucose rose by 56% and HbA1c by 14.7% (p less than 0.01). The hyperglycaemic effect of hydrochlorothiazide and its potentiation by propranolol were independent of serum potassium and of endogenous insulin secretion as measured by urine C-peptide excretion. The combination of hydrochlorothiazide and propranolol thus seems to cause serious disturbances in glycaemic control in type II diabetics by mechanisms independent of insulin secretion.

Do antihypertensive drugs precipitate diabetes?

A longitudinal population study of 1462 women aged 38-60 was carried out from 1968-9 to 1980-1 in Gothenburg, Sweden. The initial and follow up examinations included questions concerning history of diabetes and antihypertensive treatment. A considerably increased risk of developing diabetes was observed for subjects with hypertension taking diuretics (895 patient years), subjects taking beta blockers (682 patient years), and subjects taking a combination of diuretics and beta blockers (281 patient years) compared with subjects not taking antihypertensive drugs (13 855 control years). When diuretics and beta blockers were compared no difference was found in relative risk. Despite this increased risk, and because little is known about the relation between other forms of antihypertensive treatment and diabetes, diuretics and beta blockers should remain the treatments of choice in arterial hypertension.

Cardiovascular toxicity of diuretics related to magnesium depletion

The chronic administration of common loop or distal tubular diuretics may lead to somatic depletion of Mg2+. The resultant deficiency of this cation causes an increase in intramyocardial cytosolic Ca2+ and aggravates the decrease in intramyocardial K+ provoked by diuretics through their hyperkaliuretic effect. Thus the myocardium is electrically destabilized and cardiac arrhythmias may develop. Mg2+ deficiency positively contributes to the development of atherogenic alterations in lipid metabolism, vasospastic phenomena in the coronary and cerebrovascular territories, myocardial infarction and to the retardation of infarct healing and the occurrence of ventricular arrhythmias during the acute phase of infarction.

Hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome: a common endocrinopathy with distinct pathophysiologic features

The HAIR-AN syndrome that consists of hyperandrogenism (HA), insulin resistance (IR), and acanthosis nigricans (AN) is an underdiagnosed endocrinopathy, because hyperandrogenic women are not commonly screened for insulin resistance or acanthosis nigricans. The distinct pathophysiologic features of the HAIR-AN syndrome are discussed in detail. In this syndrome, the primary pathophysiologic derangements are the insulin resistance and the hyperandrogenism. The acanthosis nigricans is an epiphenomenon of these primary processes. In patients with the HAIR-AN syndrome, the degree of severity of the insulin resistance is positively correlated with the degree of severity of the hyperandrogenism. In patients with adequate pancreatic beta-islet cell reserve, insulin resistance results in a long-term increase in circulating insulin levels. The hyperinsulinemia probably directly stimulates ovarian androgen production. In turn, hyperandrogenism itself produces insulin resistance. This positive feedback loop between insulin resistance and hyperandrogenism propagates the disease, and increases its severity over time. The relationship between insulin resistance and hyperandrogenism may explain the hyperandrogenemia seen in the following disease processes: obesity, acromegaly, lipoatrophic diabetes, leprechaunism, and Kahn types A and B insulin resistance.

Effect of duration of low-dose oral contraceptive administration on carbohydrate metabolism

Two hundred and ten healthy young women volunteered to take a combined oral contraceptive (OC) and to have glucose tolerance in insulin secretion measured in a projected 3-year study with roughly annual investigations. Although the dropout rate was high, glucose tolerance was noted to deteriorate progressively and insulin secretion to rise initially, but thereafter they remained constant. Eventually, insulin levels were lower than would have been expected from the prevailing glucose values. This combination of steroids produced marked insulin resistance to which the pancreas could respond by further insulin secretion. It is suggested that levonorgestrel is too strong a progestin for routine use in the combined OC, and it is recommended that its dose be reduced further or that weaker progestins such as norethindrone be used.