Educational level and risk profile of cardiac patients in the EUROASPIRE II substudy

STUDY OBJECTIVE

To ascertain, whether, conventional risk factors and readiness of coronary patients to modify their behaviour and to comply with recommended medication were associated with education in patients with established coronary heart disease.

DESIGN AND METHODS

EUROASPIRE II was a cross sectional survey undertaken in 1999-2000 in 15 European countries to ascertain how effectively recommendations on coronary preventions are being followed in clinical practice. Consecutive patients, men and women </=71 years who had been hospitalised for acute coronary syndrome or revascularisation procedures, were identified retrospectively. Data were collected through a review of medical records, interview, and examination at least six months after hospitalisation. The education reached was ascertained at the interview.

MAIN RESULTS

A total of 5556 patients (1319 women) were evaluated. Significantly more patients with ischaemia had only primary education, in contrast with the remaining diagnostic groups. Body mass index and glucose were negatively associated with educational level, while HDL-cholesterol was positively associated. Men with highest education had significantly lower systolic blood pressure and total cholesterol. The prevalence of current smoking decreased significantly from primary to secondary and high education only in men. Both men and women with primary educational level were more often treated with antidiabetics, and antihypertensives, but less often with lipid lowering drugs. The effectiveness of treatment was virtually the same in all education groups.

CONCLUSIONS

Patients with higher education had lower global coronary risk, than those with lower education. This should be considered in clinical practice. Particular strategies for risk communication and counselling are needed for those with lower education status.

[D-dimers in the diagnosis of deep venous thrombosis]

D-dimers (D-d) are degeneration products of fibrin. According to some recommendations (Lee et al., Ann Rev Med, 2002; 53: 15-33) the vein thromboembolism may be excluded by the determination of D-dimers level especially when the probability of diagnosis of deep vein thrombosis is less strong. The determination of D-dimers with made possible was the development of monoclonal antibodies and their detection is based on the determination using the principle of ELISA or agglutination techniques. An increased D-d level is not completely specific for venous thrombo-embolism; it may be enhanced during tumorous diseases, infections, kidney failure etc. In contrast, a negative result of the test is highly sensitive for exclusion of deep vein thrombosis or pulmonary embolism (sensitivity 90% to 100%). The authors also present their own results of a prospective study on the dynamism of D-dimer level in plasma of patients with deep vein thrombosis demonstrated by sonography at the time of start and in the course of the anticoagulant therapy. D-dimers were determined by two methods, the quantitative agglutination latex method and the rapid VIDAS ELISA method. At the time of admission, an increased level was established in up to 80% of patients using the VIDAS method and in 70% using the latex method. In the period of five to seven days after the beginning of treatment the proportions were 75% and 60%, respectively, according to the method used. After six weeks, a slightly elevated level above normal may be expected in 1/3 of patients and less than in 1/5 of patients in the later months.

Chlamydia pneumoniae IgA seropositivity is associated with increased risk for atherosclerotic vascular disease, myocardial infarction and stroke in dialysis patients

BACKGROUND

Atherosclerotic cardiovascular disease is the major cause of morbidity and mortality in patients with chronic renal failure undergoing dialysis therapy. Aim of the study was to evaluate whether there is a correlation between a past infection with Chlamydia pneumoniae inducing antibody production and the manifestation of symptomatic atherosclerotic disease in patients with chronic renal failure on hemodialysis.

METHODS

A retrospective study was designed including 151 dialysis patients with a clinical apparent atherosclerotic disease (case subjects) and 116 dialysis patients without any symptomatic atherosclerotic manifestation (control group). An ELISA was used to measure seropositivity for IgA and IgG titers.

RESULTS

Elevated IgA titers against Chlamydia pneumoniae were found in 67% of the case subjects, but only in 29% of the controls (OR 5.34, CI 2.98-9.56). Forty-five patients of the case subjects had a history of myocardial infarction (OR 5.14, CI 2.38-11.09). Prior stroke was found in 30 patients in case subjects (OR 4.37, CI 1.73-11.01). The follow-up after 3 years showed that only 20 patients died from cardiovascular disease in the control group in comparison to 57 patients in the case group (OR 2.51). IgG seropositivity revealed an OR of 1.02 (CI 1.0-2.1).

CONCLUSION

These results indicate that IgA seropositivity is associated with an increased frequency of symptomatic atherosclerotic manifestations. Especially an increased number of patients was found with prior myocardial infarction or stroke when elevated IgA titers were detected. IgA positivity seems to be a separate prospective risk factor in patients with chronic renal failure and hemodialysis for premature cardiovascular death.

Unexpected inverse relationship between insulin resistance and serum homocysteine in healthy subjects

Mild hyperhomocysteinemia has been established as a new independent risk factor for atherosclerosis and thrombosis. The metabolic syndrome of insulin resistance is associated with a high risk of coronary heart disease. Our objective was to determine if any relationship exists between the metabolic syndrome of insulin resistance in non-diabetic subjects and total serum homocysteine levels. Sixty-six healthy volunteers (33 males and 33 females) were selected from the population of Pilsen. Insulin resistance was measured by the Insulin Suppression Test using Octreotide. Steady-state plasma glucose concentrations at the end of the test period provided a quantitative measure of insulin resistance. Serum homocysteine level was estimated by high-pressure liquid chromatography. Serum folate and vitamin B12 were estimated using commercial kits on an Abbott IMx analyzer. All other laboratory tests were performed by standard methods in a routine biochemical laboratory. Subjects with the highest tertile of steady-state plasma glucose showed a significantly higher body mass index, blood pressure, fasting plasma triglyceride levels, plasminogen activator inhibitor-1 and lower HDL-cholesterol, i.e. an insulin resistance pattern. These subjects had significantly lower serum homocysteine levels compared with non-insulin resistant subjects. The negative association of insulin resistance and serum homocysteine was unexpected. The contribution of plasma folate levels to serum homocysteine levels and serum creatinine was significantly negative and positive, respectively.

Folding of the td pre-RNA with the help of the RNA chaperone StpA

The td group I intron is inserted in the reading frame of the thymidylate synthase gene, which is mainly devoid of structural elements. In vivo, translation of the pre-mRNA is required for efficient folding of the intron into its splicing-competent structure. The ribosome probably resolves exon-intron interactions that interfere with splicing. Uncoupling splicing from translation, by introducing a non-sense codon into the upstream exon, reduces the splicing efficiency of the mutant pre-mRNA. Alternatively to the ribosome, co-expression of genes that encode proteins with RNA chaperone activity promote folding of the td pre-mRNA in vivo. These proteins also efficiently accelerate folding of the td pre-mRNA in vitro. In order to understand the mechanism of action of RNA chaperones, we probed the impact of the RNA chaperone StpA on the structure of the td intron in vivo and compared it with that of the well characterized Cyt-18 protein, which is a group-I-intron-specific splicing factor. We found that the two proteins have opposite effects on the structure of the td intron. While StpA loosens the three-dimensional structure, Cyt-18 tightens it up. Furthermore, mutations that destabilize the intron structure render the mutants sensitive to StpA, whereas splicing of these mutants is rescued by Cyt-18. Our results provide direct evidence for protein-induced conformational changes within a catalytic RNA in vivo. Whereas StpA resolves tertiary contacts enabling the RNA to refold, Cyt-18 contributes to the stabilization of the native three-dimensional structure.

The pursuit of secondary prevention targets in Czech coronary patients. A comparison of EuroAspire I and II surveys

BACKGROUND

Definite evidence has been established, that coronary patients benefit from appropriate secondary prevention measures, as recommended by the European and National Guidelines. EuroAspire I (1995) and EuroAspire II (1999) were surveys aimed to evaluate the state of the implementation of guidelines into the every-day medical practice in several European countries, including Czech Republic. We wondered to what extent the practice in secondary prevention of Czech physicians, since the guidelines were published, changed during 5 years, to pursue the targets.

METHODS

We compared two surveys, undertaken in the same geographical areas of the Czech Republic. Consecutive patients, males and females, less than 71 years of age were indentified following acute coronary event or revascularisation procedure and were interviewed and examined at least 6 months after hospitalization.

RESULTS

The Czech surveys included 331 patients in EuroAspire I and 410 in EuroAspire II. In EuroAspire II, the total number of smokers decreased in males, but increased in females. The patients were more obese, had higher glucose levels as well, while blood pressure, total and LDL cholesterol and triacylglycerols were lower, than in EuroAspire I. Corresponding changes also occurred in the prevalence of hypertension and hyperlipidaemias by definitions. There was a significant increase in the use of betablockers, ACE inhibitors and hypolipidemic drugs, mainly statins. In conclusion, in spite that the compliance with the recommendations for secondary prevention improved, achievement of targets remained rather unsatisfactory, likewise in other European countries.

[Statins in the treatment of patients with arterial occlusive disease of the lower extremities]

In patients with advanced atherosclerosis manifested by arterial occlusion in the lower extremities without a baseline blood lipid disorder statin treatment caused improvement of the efficiency, i.e. prolongation of the claudication interval, while in a comparable control group without statins the efficiency deteriorated further. In patients with arterial occlusion of the lower extremities with baseline dyslipidaemia statin treatment proved protective, i.e. at least it retarded the patients' complaints. The authors recorded improvement of the prooxidation state which followed after the dynamics of improvement of the impaired blood lipid spectrum. The results admit a possible part played by the pleiotropic effect of statins.

[Changes in the risk profile and the development of hypertension in the population of Plzen 1987-1989 and 1995-1996]

OBJECTIVE

To evaluate risk factors and the general risk profile in a longitudinally followed-up cohort of the Plzen population.

MATERIAL AND METHODS

The investigation was made in a cohort of 332 men and 280 women selected from the epidemiological study PILS II (Plzen longitudinal study) examined in 1987-1989 and 1995-1995. Both investigations adhered to the standard protocol. Anamnestic data were assessed, anthropometric parameters (BMI). Blood pressure (BP) was assessed by means of a mercury sphygmomanometer using the standard procedure, biochemical parameters were examined from a blood sample on fasting in the routine laboratories of the Faculty Hospital Plzen. Changes of individual factors were evaluated by the paired Wilcoxon test and chi 2 group test resp. The global coronary risk was calculated by means of logistic coefficients from the Framingham study.

RESULTS

In the cohort which aged on average by 7.6 years the number of smokers decreased in men by 8.1% and by 3.6% in women. The blood pressure increased significantly in both sexes, there was an increase in the number of hypertensive subjects by 26.8% in men and 21.7% in women. In men there was a significant decrease of non-HDL cholesterol, in women, there was a significant increase of subjects with diabetic dyslipidaemia. The total coronary risk (Framingham score) increased after standard transposition to the age of 60 years only by 0.5% in men and women, which reflects the risk due to increased BP. The standard of treatment of hypertension was quite unsatisfactory. When using criteria SBP > or = 140 and/or DBP > or = 90 mm Hg during the second examination 71% of the patients remained without treatment. The number of subjects not aware of hypertension declined from 54% to 19.3% of subjects. A favourable indicator was the finding that there was a decline of hypertensive subjects with a high coronary risk (> or = 20% from ca 11 to 6%).

CONCLUSION

During the investigation period in the cohort which to a certain extent represents the Plzen population a certain improvement of the risk profile occurred in particular as regards smoking and disorders of the lipid spectrum, however not as regards the prevalence and treatment of hypertension. Despite the favourable development in the Czech population in the investigated cohort, obviously at the expense of poor control of hypertension, the average coronary risk did not improve.

A population study of the influence of beer consumption on folate and homocysteine concentrations

OBJECTIVE

Mild hyperhomocysteinemia is a significant and independent risk factor for vascular diseases. Blood total homocysteine concentration (tHcy) is considered to be the product of an interaction between genetic and nutritional factors notably intake of folate, vitamin B12 and pyridoxine. The aim of the study was to determine whether regular intake of beer containing large amount of folate and other vitamins influences the tHcy blood concentrations.

DESIGN

Cross-sectional population-based survey.

SETTING

Adult population, residents of Pilsen (Czech Republic) and vicinity.

SUBJECTS

Population series included 292 males and 251 females aged 35-65 y, mean age 53.4 y. All subjects were examined by a standard protocol for clinical, anthropometrical and laboratory estimations.

MAIN OUTCOME MEASURES

tHcy was measured by high-pressure liquid chromatography with fluorescent detection, blood folate and B12 levels immunochemically using commercial kits.

RESULTS

Beer intake was associated with blood folate and vitamin B12 concentrations positively and with tHcy concentration negatively. By categories of beer intake, subjects with intake of 1 l daily or more had significantly lower tHcy and higher folate concentrations than those reporting lower daily beer intake.

CONCLUSION

Moderate beer consumption may help to maintain the tHcy levels in the normal range due to high folate content. Folate from beer may thus contribute to the protective effect of alcohol consumption on cardiovascular disease in population with generally low folate intake from other nutrients.

SPONSORSHIP

Supported by grant 301/00/P089 Grant Agency of Czech Republic and Internal Grant Agency of the Ministry of Health.

Insulin-mediated glucose disposal is decreased in normal subjects with relatively low plasma magnesium concentrations

The relationship between the plasma magnesium (Mg) concentration and steady-state plasma insulin (SSPI) and glucose (SSPG) concentrations at the end of a 180-minute infusion of octreotide, insulin, and glucose was determined in 98 healthy nondiabetic subjects. For the purposes of data analysis, the population was divided into tertiles on the basis of the plasma Mg concentration: I, plasma Mg 0.83 mmol/L; II, plasma Mg 0.84 to 0.91 mmol/L; and III, plasma Mg 0.92 mmol/L. The three groups were identical in terms of age, gender distribution, and degree of obesity. However, both fasting plasma insulin (P < .05) and SSPG (P < .05) concentrations were significantly higher in the tertile (I) with the lowest plasma Mg concentration. Furthermore, there was a significant inverse correlation between plasma Mg and SSPG concentrations (r = -.27, P < .01) in the entire population. These results indicate that variations in the plasma Mg concentration have a relatively modest but significant effect on insulin-mediated glucose disposal in healthy subjects, with lower plasma Mg concentrations associated with increased insulin resistance.

[Effect of folates, vitamin B12 and life style factors on mild hyperhomocysteinemia in a population sample]

BACKGROUND

Mild hyperhomocysteinaemia (MHHcy) is a significant and independent risk factor for vascular diseases, however, its causality has not yet been unequivocally confirmed. The total homocysteine (Hcy) blood level is considered a product of genetic and lifestyle interactions, mainly folates, vitamin B12 and pyridoxine intake. In this paper we estimated the influence of these factors on MHHcy in the population.

METHODS AND RESULTS

The population sample included 292 males a 251 women, mean age 53.4 years, selected from the population study PILS II. All subjects were examined by a standard protocol for clinical, anthropometrical and laboratory examination. Hcy levels were examined by ion exchange chromatography, all other factors by commercial kits. Statistical analysis was done in quartiles of distribution by Kruskal-Wallis ANOVA, Wilcoxon's un-paired test and multiple logistic regression (stepwise). Serum total Hcy levels were in significant positive associations with age in both sexes, with BMI in males only. Negative associations of Hcy were found with plasma folates and B12 concentrations in both sexes, with alcohol consumption again only in males. Smoking and physical activity and serum methionine concentration were not associated with Hcy levels. The established associations remained significant when adjusted by multiple logistic regression. About 40% of subjects with MHHcy had low folates and/or B12 levels and a deficiency in both vitamins was found in 17% of subjects. In contrast, MHHcy also was assessed in 14% of subjects with high folates and in 17% with high B12 concentration and in as few as in 3.7% of subjects with high concentrations of both vitamins as well.

CONCLUSIONS

Nutritional factors, i.e. folates and B12 intake, seem to be the most important ones responsible for Hcy levels. A predominating influence of genetic factors may be assumed in less than one fifth of subjects with MHHcy.

[Gender differences in serum homocysteine levels and associated factors]

BACKGROUND

Homocysteine (Hcy) is an important independent risk factor for vascular diseases. Its level is determined by genetic polymorphism of several enzymes in association with nutritional factors. Higher Hcy levels were found in men than in women, however the clinical significance of this phenomenon remains to be elucidated. The aim of this study was to analyze the gender differences in Hcy levels in relation to associated factors and to assess in which range of Hcy these differences are mainly expressed.

METHODS AND RESULTS

The series comprised of 257 males and 239 females, mean age 52.9 and 52.3 years, resp., selected from the population study Pils II. All subjects were examined by a standard protocol, to assess clinical, anthropometrical and laboratory variables. Hcy and methionine levels were estimated by ion exchange chromatography, other laboratories using standard kits. The methods were validated by a reference laboratory. Statistical analyses were done by Wilcoxon's unpaired test and multiple linear regression. We found in males significantly higher Hcy levels (13.1 vs. 11.5 mumol/l, p < 0.0001) than in females. This difference persisted only in the range of normal Hcy levels (11.1, 10.2 mumol/l, p < 0.0001), i.e. up to 15 mumol/l (1st-4th quintile of the Hcy distribution) and not in the top quintile, considered as mild hyperhomocysteinaemia. We found in males, with normal Hcy levels, significantly higher serum methionine (23.8 vs. 22.4 mumol/l, p < 0.0001), creatinine (91.5 vs 80.9 mumol/l, p < 0.0001) and a lower methionine/creatinine ratio (0.25 vs. 0.27, p < 0.01). Plasma folates and B12 vitamin in males were also lower than in females, however these differences were only of a borderline statistical significance. On the other hand, in subjects with MHHcy (5th quintile) no gender differences were observed, except in creatinine.

CONCLUSIONS

Higher Hcy levels in males cannot be explained by differences in folate and B12 levels only. We considered also other factors, namely higher demethylation of methionine associated with higher creatinine production in males, which may be influenced by sex hormons.

Pharmacokinetics of orally administered estradiol valerate. Results of a single-dose cross-over bioequivalence study in postmenopausal women

A randomized, single-dose cross-over study in 32 postmenopausal women was performed to demonstrate bioequivalence of two estradiol valerate containing formulations (first sequence of Klimonorm as test preparation). The serum levels of estradiol, free and conjugated estrone were measured until 48 h after an oral dosage of 4 mg estradiol valerate (CAS 979-32-8). The mean AUC(0-48) of estradiol was calculated as 1006.6 +/- 479.4 h x pg x ml-1 (Test) and 1015.2 +/- 555.2 h x pg x ml-1 (Reference). The corresponding (AUC(0-48) of the active metabolite, free estrone, exceeded that of estradiol at 3578.3 h x pg x ml-1 (Test) and 3485.1 h x pg x ml-1 (Reference). Much higher was the AUC(0-48) for conjugated estrone at 132.4 h x ng x ml-1 (Test) and 133.6 h x ng x ml-1 (Reference). Mean estradiol Cmax values of 39.8 +/- 17.7 pg/ml (Test) and 42.9 +/- 21.0 pg/ml (Reference) were attained 8.2 +/- 4.5 h (Test) and 10.0 +/- 5.9 h (Reference) after the administration of 4 mg estradiol valerate. Maximal free estrone concentrations of 163 pg/ml (Test) and 174.3 pg/ml (Reference) were reached after 7.2 h (Test) and 7.5 h (Reference). Maximal conjugated estrone concentrations of 15.5 ng/ml (Test) and 16.2 ng/ml (Reference) were reached after 2.4 h (Test) and 2.0 h (Reference). The terminal elimination half-life of estradiol was calculated at 16.9 +/- 6.0 h (Test) and 15.0 +/- 4.8 h (Reference), that of free estrone at 16.3 h (Test) and 13.5 h (Reference), that of conjugated estrone at 11.8 h (Test) and 10.6 h (Reference). After logarithmic transformation, the 90% confidence intervals of the AUC(0-48) and Cmax ratios for estradiol and also for the metabolites (free and conjugated estrone) were within the acceptance ranges for bioequivalence. Therefore the test preparation and the reference preparation are bioequivalent.

[Calcium channel blockers in the treatment of hypertension and ischemic coronary disease. Conflicts in their evaluation]

Calcium channel blockers represent a pharmacologically non homogenic group. Verapamil and diltiazem have myocardial component of their effect, which acts against activated sympathicus. Short acting dihydropyridines (nifedipin) appear to be harmful by patients after myocardial infarction which is caused by the reflex sympathetic response to the predominant vasodilation. In the treatment of cardiovascular disease (e.g. hypertension, coronary vascular disease) are short acting dihydropyridines not recommended. Dihydropyridines of the new generation (amlodipin, felodipin, isradipin, lacidipin, nicardipin, nimodipin, nisoldipin, nitrendipin) induce less tachycardia due to their favorable kinetic features. If the slow movement in blood or at the receptor site is not a result of molecule features there is necessary to use retarded preparations of active substance. Nevertheless, commonly used retarded preparations fulfil this requirement only incompletely. The desirable quality is provided by modern form of retardation. (e.g. GITS) only.

[Analysis of mortality trends in the West Bohemian Region in comparison with the entire Czech Republic 1988-1995]

BACKGROUND

Unfavourable trends in Czech republic (CR) started in the sixties and peaked in the late eighties i.e. in years when a dramatic mortality fall was observed in most western european countries. So, CR belonged among those Eastern European countries in that total and cardiovascular mortality showed increasing and alarming trends. West Bohemia Region (WB) was characterised by the concentration of heavy industry and high environmental pollution. Because of its geographical position on the western frontier, it was generally restricted in capital investment in the past. We wondered whether these phenomenon were reflected in higher mortality rates than in the rest of CR and which changes occurred after the year 1989.

METHODS AND RESULTS

We compared the age standardized mortality data from 1988, 91, 93 and 95 in CR and WB for total mortality, cardiovascular mortality, coronary heart disease, strokes, malignancies and respiratory diseases. Data were age-adjusted for "World Population Standards" and rates were given for 100,000 inhabitants. In the whole CR a significant decrease of total, cardiovascular and cancer mortality was observed from 1988 to 1995. In WB these trends were similar, however in comparison to the whole CR the mortality rates remained in each respective period higher for total, cancer (mainly lung cancer) mortality and for non specific respiratory disease. In contrast, the coronary mortality rates in CR and WB were similar, however in WB after a temporary decrease in 1993 a significant increase in 1995 was observed. On the other hand the stroke mortality rates which were until 1993 in WB higher, significantly decreased in 1995 below the rates for CR. The cause of higher mortality rates in WB are far from being clear. To elucidate this observation epidemiologic studies of environmental pollution, life style of the population and socioeconomic factors are necessary, even as a further monitoring of regional mortality rates and trends.

[Detection of risk of insulin resistance in the population]

BACKGROUND

To assess the validity of hyperinsulinemia as a marker of insulin resistance (IR) and to find other common risk factors (RF) associated with IR.

METHODS AND RESULTS

Sample of 91 healthy volunteers with normal glucose tolerance (NGT) was selected from the adult Pilsen population. Following examinations according to the standard protocol were done: medical history, physical examination, body mass index-BMI (kg/m2), waist to hip ratio (WHR), casual blood pressure (BP), plasma lipids, 7-point oral glucose tolerance test (oGTT), IRI (immunoreactive insulin) curve, insulin suppression test (IST) for the evaluation of IR. Specificity and sensitivity of IRI levels as markers of IR were tested. Association between IR measured by IST and fasting and postload IRI was evaluated by single correlation. Multiple logistic regression (MLR) was applied for the calculation of IR prediction. Fasting and postload hyperinsulinemia (mU/l) have very good specificity (about 90%) for the discovery of IR, but sensitivity was different: fasting IRI > 20 = 19%, IRI in the 2nd h of oGTT > 90 = 30%, IRI sum (fasting IRI + IRI in the 1st and 2nd h of oGTT) > 150 = 51%. Simple correlation between IRI and IR was better in IRI sum (0.56 p < 0.001) than fasting IRI (0.28, p < 0.05). Using MLR HDL-ch, TG and IRI sum were selected as the significant and independent factors for the prediction of IR in the subjects from the population (prediction accuracy about 68%).

CONCLUSIONS

Fasting IRI is not too good marker for IR assessment in the NGT subjects from the Pilsen population. IRI sum was the best marker for IR and together with HDL-ch and TG level were selected as the significant predictive factors for IR.

Effect of variations in plasma magnesium concentration on resistance to insulin-mediated glucose disposal in nondiabetic subjects

Eighteen nondiabetic volunteers were selected for these studies on the basis of their plasma magnesium (Mg) concentrations defined as being either high (> 0.83 mmol/L) or low (< 0.80 mmol/L). Although different in Mg concentration (0.90 +/- 0.02 vs. 0.73 +/- 0.01 mmol/L), the 2 groups were comparable in terms of age, gender distribution, body mass index, and waist to hip girth. Measurements were made of their plasma glucose and insulin concentrations in response to a 75-g oral glucose load and the steady state plasma insulin and glucose (SSPG) concentrations at the end of an 180-min infusion of octreotide, insulin, and glucose. The low Mg group had significantly higher plasma glucose (P < 0.001) and insulin (P < 0.002) concentrations after the oral glucose challenge. Although the steady state plasma insulin concentrations were similar during the infusion study, the SSPG concentration was significantly (P < 0.001) greater in the low Mg group (11.9 +/- 0.9 vs. 6.6 +/- 0.9 mmol/L). Finally, when the 18 patients were analyzed together, there were significant (P < 0.05 to P < 0.01) inverse correlations between Mg concentrations and glucose (r = -0.68) and insulin (r = -0.51) areas and SSPG concentrations (r = -0.60). Thus, a low Mg concentration in nondiabetic subjects was associated with relative insulin resistance, glucose intolerance, and hyperinsulinemia.