Association of low HDL and HDL2 cholesterol with coronary heart disease in noninsulin-dependent diabetics

The Role of High-Density Lipoprotein Cholesterol in 2022

PURPOSE OF THE REVIEW

High-density lipoproteins (HDL) are responsible for the transport in plasma of a large fraction of circulating lipids, in part from tissue mobilization. The evaluation of HDL-associated cholesterol (HDL-C) has provided a standard method for assessing cardiovascular (CV) risk, as supported by many contributions on the mechanism of this arterial benefit. The present review article will attempt to investigate novel findings on the role and mechanism of HDL in CV risk determination.

RECENT FINDINGS

The most recent research has been aimed to the understanding of how a raised functional capacity of HDL, rather than elevated levels per se, may be responsible for the postulated CV protection. Markedly elevated HDL-C levels appear instead to be associated to a raised coronary risk, indicative of a U-shaped relationship. While HDL-C reduction is definitely related to a raised CV risk, HDL-C elevations may be linked to non-vascular diseases, such as age-related macular disease. The description of anti-inflammatory, anti-oxidative and anti-infectious properties has indicated potential newer areas for diagnostic and therapeutic approaches. In the last two decades inconclusive data have arisen from clinical trials attempting to increase HDL-C pharmacologically or by way of recombinant protein infusions (most frequently with the mutant A-I _Milano); prevention of stent occlusion or heart failure treatment have shown instead significant promise. Targeted clinical studies are still ongoing.

High-density lipoprotein subclasses and their relationship to cardiovascular disease

OBJECTIVE

To assess the clinical utility of measuring high-density lipoprotein (HDL) subfractions to assess coronary heart disease (CHD) risk.

METHODS

Literature review of 80 published investigations.

RESULTS

Measurements of HDL2b by gradient gel electrophoresis provided more consistent evidence of CHD risk than measurement of HDL2 cholesterol. Five of the seven studies that compared the extent or progression of atherosclerosis with gradient gel electrophoresis estimates of HDL subclasses (71%) assigned statistical significance to HDL2b. Ten of the 11 case-control comparisons (91%) reported lower HDL2b in cases. In contrast, of the 16 association studies relating HDL2 cholesterol and HDL3 cholesterol to extent of disease, five reported no significant relationships with either subfraction, two reported significant relationships with both HDL2 and HDL3 cholesterol, four reported significant relationships with HDL2 but not HDL3 cholesterol, and five reported relationships with HDL3 but not HDL2 cholesterol. Forty-five percent of the case-control comparisons reported that both HDL2 cholesterol and HDL3 cholesterol were significantly lower in cases than controls, 17% failed to find significance for either subfraction, and the remainder reported significantly lower values in cases for HDL2 cholesterol only (26%) or HDL3 cholesterol only (11%). On average, the case-control differences were similar for HDL2 (-0.12 ± 0.01 mmol/L) and HDL3 cholesterol (-0.10 ± 0.02 mmol/L), although relative to controls, the percent reduction was twice as great for HDL2 (-25.7 ± 2.9%) than HDL3 cholesterol (-12.1 ± 1.5%). Eight prospective studies were identified and four reported that both HDL2 and HDL3 predicted lower risk for CHD, one reported reductions in risk for HDL2 but not HDL3 cholesterol, and three reported reductions in risk for HDL3 but not HDL2 cholesterol. None of the prospective studies show that measurements of HDL cholesterol subfractions improve the identification of persons at risk.

CONCLUSIONS

HDL2 and HDL3 cholesterol do not distinguish cardioprotective differences between HDL subclasses. More extensive characterization of HDL particles by one or two dimensional gel electrophoresis, ion mobility, or ultracentrifugation may provide more specific information about CHD risk than the measurement of HDL cholesterol, HDL3 cholesterol, or HDL2 cholesterol.

Prospective studies on the relationship between high-density lipoprotein cholesterol and cardiovascular risk: a systematic review

Epidemiological studies have extensively evaluated the association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) risk. The objective of this systematic review was to enumerate the number of original prospective studies that showed a significant association between HDL-C and CVD risk and provided evidence of the consistency of this association across other lipid risk factors. A systematic MEDLINE literature search identified 53 prospective cohort and five nested case-control studies that provided multivariate assessments of the association between HDL-C and CVD risk. Among these 58 prospective studies, 31 studies found a significant inverse association between HDL-C and CVD risk for all CVD outcomes and subpopulations studied, whereas 17 studies found a significant association for some CVD outcomes and/or subpopulations assessed. The ratio of studies that found a significant association out of the total studies identified was similar across all CVD outcomes, although there was less evidence for stroke and atherosclerotic outcomes. Only seven studies tested for the consistency of this association across other lipid risk factors, of which six studies suggested that the association was consistent across other lipid levels. In conclusion, the association between HDL-C and CVD risk is significant and strong, although further evidence may be needed to establish whether this association is consistent across other lipid risk factors. Furthermore, uncertainties remain regarding the mechanism in which HDL-C exerts its effects, suggesting a need for further research focused on new methods for reliable measurement.

Pathogenesis and management of diabetic dyslipidemia

Patients with diabetes mellitus have a 2- to 4-fold increased risk of atherosclerotic cardiovascular, peripheral vascular, and cerebrovascular disease, which are the leading causes of morbidity and mortality in this population. Several epidemiological studies have shown an association between diabetic dyslipidemia, which is characterized by hypertriglyceridemia, low levels of high density lipoprotein-cholesterol, postprandial lipemia and small, dense low density lipoprotein-cholesterol (LDL-C) particles, and the occurrence of cardiovascular disease. Other studies have established the beneficial effects of lipid lowering on the reduction of major coronary events in diabetic patients. The recent National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) guidelines emphasize diabetes as a coronary heart disease risk equivalent. The NCEP ATP III states that elevated LDL-C is a major risk factor for coronary heart disease, and the primary goal of risk-reduction therapy is the reduction of LDL-C levels to 100 mg/dL. This article defines and describes diabetic dyslipidemia and its etiology and pathogenesis, as well as reviewing guidelines and recommendations for treatment of this disorder. Treatment of diabetic dyslipidemia includes 1) lifestyle modifications: physical activity and a diet low in saturated fats and cholesterol and high in complex carbohydrates and fiber; and 2) pharmacological treatment with (i) oral antihyperglycemic agents: metformin and thiazolidinediones; (ii) weight reduction drugs: orlistat and sibutramine and; (iii) lipid-lowering drugs: HMG-CoA reductase inhibitors, fibric acid derivatives, nicotinic acid, and bile acid sequestrants.

Apolipoprotein AI- and AI:AII-containing lipoproteins in white men and women of the HERITAGE Family study: Associations with metabolic risk profile variables

It is now well established that an increased high-density lipoprotein (HDL) cholesterol level, especially in the HDL(2) subfraction, is associated with a reduced risk of coronary heart disease (CHD). However, little is known about the associations between the apolipoprotein (apo) composition of HDL and CHD metabolic risk factors. In the present study, we examined the gender differences in plasma concentration of HDL containing apo AI only (LpAI) versus both apoAI and apoAII (LpAI/AII), and also compared their associations with body composition, adipose tissue (AT) distribution, and metabolic risk profile variables. For that purpose, we measured fasting plasma lipoprotein-lipid levels including LpAI and LpAI/AII concentrations in a sample of 215 men and 174 women, all Caucasians, of the HERITAGE Family Study. All subjects underwent anthropometric, body fatness (underwater weighing) and abdominal AT accumulation (computed tomography) measurements. We found that, women had higher LpAI and lower LpAI/AII concentrations compared with men. Whereas in women, LpAI levels were correlated to body fat mass and waist circumference, no association between body composition, fat distribution, and LpAI concentrations was noted in men. Increased LpAI concentrations were associated with higher HDL(2) cholesterol levels in both men and women. Overall, elevated LpAI and LpAI/AII concentrations showed contrasting associations with metabolic risk profile variables as high LpAI, but not LpAI/AII concentrations were associated with a more favorable metabolic risk profile. We also found that high HDL cholesterol appeared to be more closely related to a better metabolic risk profile than high LpAI in both genders. Our results suggest that LpAI and HDL cholesterol levels are good correlates of the metabolic profile, but that HDL cholesterol concentrations could still represent a better index in CHD risk assessment.

HDL in atherosclerosis: actor or bystander?

Despite dramatic improvement in treatments for reducing risk for coronary heart disease (CHD), it is still the leading cause of mortality in the developed world. In the past decade, a major improvement in reducing low-density lipoprotein (LDL) cholesterol has been achieved with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). This approach has been shown to be beneficial in both primary and secondary prevention of CHD. On the other hand, while a reduced high-density lipoprotein (HDL) cholesterol level is an independent CHD risk factor, no HDL cholesterol goal has yet been established. The Helsinki Heart Study and the Veterans Affairs High-density Lipoprotein Intervention Trial documented that increasing HDL cholesterol with gemfibrozil significantly decreases coronary events or stroke in CHD patients either with elevated non-HDL cholesterol or normal LDL cholesterol levels plus low HDL cholesterol. Investigations with statins have focused on their efficacy not only in significantly decreasing total cholesterol, LDL cholesterol, and triglyceride levels but also in increasing HDL cholesterol concentrations. The two different classes of drugs (statins and fibrates) have different effects on the various HDL subspecies. As new members of these drug classes and other novel drugs are emerging, there is interest in clarifying whether HDL is only a bystander (an indicator for other CHD risk factors) or it has an active role in the development of CHD. If HDL has an active role, there is a need to determine if any HDL subspecies are protective. It is now clear that HDL plays a pivotal role in cellular cholesterol efflux via the interaction of apolipoprotein A-I with the ATP binding cassette transporter A-1. Thereafter the cholesterol is esterified by lecithin:cholesterol acyltransferase; HDL is remodeled by cholesterol ester transfer protein (CETP) and hepatic lipase. The cholesterol in HDL can either be transferred to apolipoprotein B-containing particles via CETP or delivered directly to the liver with the help of scavenger receptor B1.

A single daily dose of soybean phytosterols in ground beef decreases serum total cholesterol and LDL cholesterol in young, mildly hypercholesterolemic men

BACKGROUND

Consumption of phytosterol-supplemented margarine lowers total plasma cholesterol (TC) and LDL-cholesterol concentrations in older middle-aged hypercholesterolemic individuals. The effects of incorporating phytosterols into lower-fat foods on the plasma lipids of young men at increased risk of developing cardiovascular disease have not been studied.

OBJECTIVE

We tested the hypothesis that a single daily dose of soybean phytosterols added to ground beef will lower plasma TC and LDL-cholesterol concentrations in mildly hypercholesterolemic young men.

DESIGN

In a triple-blind, 4-wk study, 34 male college students with elevated plasma TC (5.85 +/- 0.70 mmol/L), LDL cholesterol (4.02 +/- 0.60 mmol/L), and TC:HDL cholesterol (5.5 +/- 1.2) were randomly assigned to the control (ground beef alone) or treatment (ground beef with 2.7 g of phytosterols) group. The phytosterol mixture was two-thirds esterified and one-third nonesterified and consisted of beta-sitosterol (48%), campesterol (27%), and stigmasterol (21%).

RESULTS

Consumption of phytosterol-supplemented ground beef lowered plasma TC and LDL-cholesterol concentrations and TC:HDL cholesterol from baseline by 9.3%, 14.6%, and 9.1%, respectively (P < 0.001). The LDL particle size did not change, suggesting that the decrease was primarily of particle number. The decreases were similar in subjects with (n = 8) and without (n = 9) a family history of premature cardiovascular disease. No significant changes were found in the control group.

CONCLUSION

Phytosterol-supplemented ground beef effectively lowers plasma TC and LDL cholesterol and has the potential to become a functional food to help reduce the risk of cardiovascular disease.

Clinical evaluation of plasma high-density lipoprotein subfractions (HDL2, HDL3) in non-insulin-dependent diabetics with coronary artery disease

STATEMENT OF THE PROBLEM

Low levels of high-density lipoprotein cholesterol (HDL-C) have a strong association with coronary artery disease (CAD) in patients with non-insulin-dependent diabetes mellitus (NIDDM). In this study, we tried to evaluate whether one or both of the major HDL subclasses (HDL2, HDL3) is strongly associated with the risk of CAD in NIDDM subjects.

METHODS

The separation of HDL subclasses was carried out by ultracentrifugation in a Beckman Airfuge. HDL2 subclass was isolated from the supernatant and its cholesterol content was measured enzymatically. Plasma HDL3 cholesterol was calculated as the difference between results for total HDL cholesterol and HDL2 cholesterol.

RESULTS

NIDDM patients with CAD had significantly higher triglyceride levels compared to either control (217.09+/-55.04 versus 89.62+/-31.29 mg/dl, P=.001) or CAD patients without NIDDM (217.09+/-55.04 versus 156.28+/-46.39 mg/dl, P<.05). However, in the diabetic patients with CAD, there was a statistically significant decrease in HDL cholesterol (39.63+/-8.59 versus 55.86+/-13.49 mg/dl, P<.01), HDL2 cholesterol (8.74+/-3.28 versus 16.95+/-5.73 mg/dl, P<.001), and HDL3 cholesterol (31.23+/-7.41 versus 38.91+/-8.93 mg/dl, P<.05) in comparison to nondiabetic controls. Moreover, in the comparison between non-insulin-dependent diabetics with CAD and CAD subjects without NIDDM, HDL cholesterol (39.63+/-8.59 versus 46.13+/-6.33 mg/dl, P<.05) and HDL2 cholesterol (8.74+/-3.28 versus 11.84+/-4.01 mg/dl, P<.02) were significantly reduced, while HDL3 cholesterol levels were (31.23+/-7.41 versus 34.29+/-7.94 mg/dl, P=.92) unaltered. Additionally, the percentage reduction of cholesterol in HDL2 fraction was proportionately greater than the decrease in HDL3 subclass in both comparisons. Moreover, in NIDDM with CAD, HDL cholesterol was reduced by 29% and 14%, HDL2 cholesterol by 48% and 26%, and HDL3 cholesterol by 20% and 9%, compared relatively to controls and CAD subjects without NIDDM.

CONCLUSIONS

In conclusion, HDL2 is the more variable subclass and reflects changes in HDL. This suggests that the protective role of total HDL against CAD is mainly mediated through HDL2 fraction. Therefore, HDL2 might be a better predictor of coronary heart disease than total HDL, in non-insulin-dependent diabetes mellitus.

Distribution of ApoA-I-containing HDL subpopulations in patients with coronary heart disease

High density lipoproteins (HDLs) and their subspecies play a role in the development of coronary heart disease (CHD). HDL subpopulations were measured by 2-dimensional nondenaturing gel electrophoresis in 79 male control subjects and 76 male CHD patients to test the hypothesis that greater differences in apolipoprotein (apo)A-I-containing HDL subpopulations would exist between these 2 groups than for traditional lipid levels. In CHD subjects, HDL cholesterol (HDL-C) was lower (-14%, P<0.001), whereas total cholesterol and the low density lipoprotein cholesterol/HDL-C ratio were higher (9% [P:<0.05] and 21% [P:<0.01], respectively) compared with control levels. No significant differences were found for low density lipoprotein cholesterol, triglyceride, and apoA-I levels. In CHD subjects, there were significantly (P:<0.001) lower concentrations of the large lipoprotein (Lp)A-I alpha(1) (-35%), pre-alpha(1) (-50%), pre-alpha(2) (-33%), and pre-alpha(3) (-31%) subpopulations, whereas the concentrations of the small LpA-I/A-II alpha(3) particles were significantly (P:<0.001) higher (20%). Because alpha(1) was decreased more than HDL-C and plasma apoA-I concentrations in CHD subjects, the ratios of HDL-C to alpha(1) and of apoA-I to alpha(1) were significantly (P:<0.001) higher by 36% and 57%, respectively, compared with control values. Subjects with low HDL-C levels (</=35 mg/dL) have different distributions of apoA-I-containing HDL subpopulations than do subjects with normal HDL-C levels (>35 mg/dL). Therefore, we stratified participants according to HDL-C concentrations into low and normal groups. The differences in lipid levels between controls and HDL-C-matched cases substantially decreased; however, the significant differences in HDL subspecies remained. Our research findings support the concept that compared with control subjects, CHD patients not only have HDL deficiency but also have a major rearrangement in the HDL subpopulations with significantly lower alpha(1) and pre-alpha(1-3) (LpA-I) and significantly higher alpha(3) (LpA-I/A-II) particles.

Comparative analysis of plasma and erythrocyte 7-ketocholesterol as a marker for oxidative stress in patients with diabetes mellitus

OBJECTIVES

To reveal increased lipid peroxidation in diabetics by quantification of cholesterol oxidation products (COPs) not only in plasma, but also in erythrocytes.

DESIGN AND METHODS

We quantified 7-ketocholesterol (7-kCho) by gas chromatography-mass spectrometry as a surrogate measure for COPs. These assays were performed on both plasma and erythrocytes in 20 control subjects and 20 treated patients with relatively poorly controlled Type 2 diabetes.

RESULTS

Both plasma and erythrocyte 7-kCho levels in diabetics were significantly higher than those in control subjects. Although neither plasma nor erythrocyte 7-kCho levels were associated with markers for glucose tolerance in diabetics, a negative correlation of serum HDL-cholesterol levels with erythrocyte, but not plasma, 7-kCho levels was found.

CONCLUSION

Increased oxidative stress in diabetics affects oxidation of cholesterol. Assays of COPs not only in plasma, but also in erythrocytes, may yield complementary information in lipid peroxidation.

Preventing, stopping, or reversing coronary artery disease--triglyceride-rich lipoproteins and associated lipoprotein and metabolic abnormalities: the need for recognition and treatment

A substantial number of treated patients with or at high risk for coronary artery disease continue to have fatal and nonfatal coronary artery events in spite of significant reduction of elevated levels of low-density lipoprotein cholesterol. Other lipoprotein abnormalities besides an elevated level of low-density lipoprotein cholesterol contribute to risk of coronary artery disease and coronary artery events, and the predominant abnormalities that appear to explain much of this continued risk are an elevated serum triglyceride level and a low level of high-density lipoprotein cholesterol. Most patients with coronary artery disease have a mixed dyslipidemia with hypertriglyceridemia, which is associated and metabolically intertwined with other atherogenic risk factors, including the presence of triglyceride-rich lipoprotein remnants, low levels of high-density lipoprotein cholesterol, small, dense, low-density lipoprotein particles, postprandial hyperlipidemia, and a prothrombotic state. Aggressive treatment of these patients needs to focus on these other lipoprotein abnormalities as much as on low-density lipoprotein cholesterol. Combination drug therapy will usually be required. Reliable assessment of risk of coronary artery disease from lipoprotein measurements and response to therapy requires inclusion of all atherogenic lipoproteins in laboratory measurements and treatment protocols. At present this may be best accomplished by use of non-high-density lipoprotein cholesterol (total cholesterol minus high-density lipoprotein cholesterol) calculated from standard laboratory lipoprotein values. Ultimately, a more comprehensive assessment of coronary artery disease risk and appropriate therapy may include measurement of lipoprotein subclass distribution including determination of low-density lipoprotein particle concentration and sizes of the various lipoprotein particles.

Impact of insulin resistance on lipoprotein subpopulation distribution in lean and morbidly obese nondiabetic women

The purpose of this study was to examine the effects of insulin resistance on the lipoprotein subpopulation distribution of very-low-density, low-density, and high-density lipoproteins (VLDL, LDL, and HDL) in lean and morbidly obese nondiabetic women. Lean women (body mass index [BMI], 20 to 27 kg/m2) stratified by BMI were divided into insulin-sensitive (SL, n = 12) and insulin-resistant (RL, n = 8) groups according to Bergman's minimal model, SI. A group of obese women (BMI, 30 to 53 kg/m2), also stratified by BMI, were divided into insulin-sensitive (SO, n = 10) and insulin-resistant (RO, n = 11) groups in a similar fashion. Resistant groups were similar to sensitive groups (SL v RL and SO vRO) in age, weight, percent body fat, and waist circumference, ie, total and regional adiposity. VLDL, LDL, and HDL subpopulation distributions were determined in fasting plasma samples by nuclear magnetic resonance (NMR) spectroscopy. The average particle sizes of all 3 classes of lipoproteins were similar for the SL and RL groups. In contrast, RO subjects had larger VLDL, smaller LDL, and smaller HDL, than SO subjects (P < .05). Lower concentrations of large LDL and large HDL were found in RO compared with SO subjects (P < .05). In obese women, but not in lean women, VLDL size was associated with plasma insulin (r = .60, P < .005), while LDL size and HDL size were negatively correlated with plasma insulin (r = -.39, P < .05 and r = -.38, P < .05) and positively correlated with SI (r = .54, P < .01 and r = .42, P < .05). These results suggest that in obese women, insulin resistance may be involved in the formation of lipoprotein subpopulation distributions that are associated with vascular disease.

Lipoprotein subpopulation distributions in lean, obese, and type 2 diabetic women: a comparison of African and white Americans

OBJECTIVE

Abnormal subpopulation distributions of plasma lipoproteins have been reported in white American (WA) women with obesity and type 2 diabetes that explain part of the elevated rate of cardiovascular disease in these patients. This study examined if these perturbations also occur in obese and diabetic African American (AA) women and compared the lipoprotein profiles with WA counterparts.

RESEARCH METHODS AND PROCEDURES

We determined the lipoprotein subpopulation distribution in the plasma of 51 lean women (29 WA, 22 AA, body mass index [BMI] < 30), 50 obese women (27 WA, 23 AA, BMI > 30), and 43 obese women with type 2 diabetes (27 WA, 16 AA), by nuclear magnetic resonance spectroscopy.

RESULTS

AA diabetic women, like WA diabetic women, had a larger average very low density lipoprotein (VLDL) size, elevated levels of small low density lipoprotein cholesterol (LDL-C), and lower levels of small high density lipoprotein cholesterol (HDL-C), when compared to lean controls (p<0.05). These differences were accompanied by higher VLDL-triglycerides (TG) and LDL-C in WA (p<0.05), but not in AA. Although the effects of obesity and diabetes on lipoprotein subpopulation were fairly similar for AA and WA, some racial differences, particularly with respect to HDL, were observed.

DISCUSSION

The atherogenic perturbations in lipoprotein profiles of obese AA women, particularly those with diabetes, were relatively similar to those found in WA women and may be contributing to the increased rate of cardiovascular disease (CVD) in AA with obesity and diabetes. The parameters of subpopulation distribution may provide better markers for CVD than lipid concentrations alone, particularly in AA women. Furthermore, subtle racial differences in lipoprotein profiles suggest that race-specific criteria may be needed to screen patients for CVD.

Pathogenesis of atherosclerosis in diabetes and hypertension

Prevalence of atherosclerotic vascular disease is markedly increased among individuals with diabetes-mellitus and hypertension. Its major clinical manifestations are consequences of atherosclerosis of coronary arteries, cerebral arteries and large arteries of lower extremities. Thus, atherosclerotic vascular disease is the major cause of mortality and significant morbidity in diabetes and hypertension. Dyslipidemia, hyperinsulinemia, and central obesity seem to be associated with increased risk of atherosclerosis, along with the development of hypertension and diabetes (NIDDM). Insulin resistance is the fundamental factor in this situation which has strong genetic predisposition. Accelerated atherosclerosis in diabetes due to mechanism unique to diabetes like non-enzymatic glycation of proteins, oxidative modification of lipoproteins, formation of lipoproteins immune complexes, lipoproteins aggregation, disturbances of cell replication and growth factors and propensity to thrombosis are clearly established. Therapeutic implication for the prevention of atherosclerosis in diabetes and hypertension clearly emphasizes the need to achieve tight control of hyperglycemia, hypertension, and hyperlipidemia in addition to avoiding cigarette smoking and developing obesity.

Effects of glucose and insulin on rat apolipoprotein A-I gene expression

We have examined the regulation of apolipoprotein A-I (apoA-I) gene expression in response to glucose and insulin. In Hep G2 cells, endogenous apoA-I mRNA was suppressed by one-half or induced 2-fold following 48 h of exposure to high concentrations of glucose (22.4 mM) or insulin (100 microunits/ml), respectively, compared with control. Transcriptional activity of the rat apoA-I promoter (-474 to -7) in Hep G2 cells paralleled endogenous mRNA expression, and this activity was dependent on the dose of glucose or insulin. Deletional analysis showed that a 50-base pair fragment spanning -425 to -376 of the promoter mediated the effects of both insulin and glucose. Within this DNA fragment there is a motif (-411 to -404) that is homologous to a previously identified insulin response core element (IRCE). Mutation of this motif abolished not only the induction of the promoter by insulin but also abrogated its suppression by glucose. Electrophoretic mobility shift assay analysis of nuclear extracts from Hep G2 cells revealed IRCE binding activity that formed a duplex with radiolabeled probe. The IRCE binding activity correlated with insulin induction of apoA-I expression. In summary, our data show that glucose decreases and insulin increases apoA-I promoter activity. This effect appears to be mediated by a single cis-acting element.

Epidemiologic aspects of lipid abnormalities

Existing cholesterol guidelines aimed at preventing cardiovascular disease emphasize the role of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol in lipid management decisions, with a subsidiary role for high-density lipoprotein (HDL) cholesterol in guiding treatment and little role for triglycerides. In this article, epidemiologic evidence is reviewed relating to the independent value of lipid factors in prediction of cardiovascular disease risk, including TC, LDL cholesterol, HDL cholesterol, very-low-density lipoprotein (VLDL) cholesterol and triglycerides, LDL particle size ("pattern B"), and the TC/HDL-cholesterol ratio. Several observations are highlighted. Triglycerides appear to be an independent risk factor in specific populations. Postprandial triglycerides may be superior to fasting triglycerides as a predictor of risk. LDL particle size does not have independent predictive value after adjustment for triglycerides. Particular emphasis is placed on the observation that the single most predictive lipid factor is the TC/HDL-cholesterol ratio, which implicitly incorporates information on both LDL and triglycerides in the numerator. This is the best predictor both of outcome and of treatment benefit, and its predictive value appears to be maintained into older age. It is concluded that increasing emphasis should be placed on the TC/HDL cholesterol ratio in epidemiologic analyses and in monitoring patients on therapy for dyslipidemia.

Postprandial lipoprotein metabolism in normotriglyceridemic non-insulin-dependent diabetic patients: influence of apolipoprotein E polymorphism

Non-insulin-dependent diabetes mellitus (NIDDM) is associated with postprandial lipoprotein clearance defects that are correlated with the fasting hypertriglyceridemia widely observed in NIDDM patients. The aim of this study was to determine if such postprandial disturbances are found in NIDDM patients strictly normotriglyceridemic in the fasting state, and if the apolipoprotein E (apo E) polymorphism influences postprandial metabolism of intestinally derived lipoproteins. The vitamin A-fat loading test was used in 18 normotriglyceridemic NIDDM patients and seven normotriglyceridemic obese controls, and postprandial triglyceride (TG) and retinyl palmitate (RP) concentrations were evaluated in total plasma, and in the chylomicron (Sf > 1,000) and nonchylomicron (Sf < 1,000) fractions isolated by ultracentrifugation. NIDDM patients exhibited an amplified response of both TG and RP as compared with obese controls in the three fractions. Incremental TG response to the oral fat load was strongly correlated with fasting TG level (r = .80, P < .0001) in the whole study population. Postprandial lipoprotein profiles were distinguished in NIDDM patients according to apo E phenotype: despite normal fasting TG levels in E3/3 (n = 6), E2/3 (n = 6), and E3/4 (n = 6), postprandial RP response was twofold to threefold higher in E2/3 and E3/4 patients than in the common E3/3 phenotype. Contrasting lower postprandial TG increment and lower fasting and postprandial high-density lipoprotein (HDL) and HDL3 cholesterol levels were observed in E3/4 versus E3/3 patients, possibly reflecting modifications in lipid content of the postprandial lipoproteins driven by a differential lipid transfer activity depending on apo E isoform. These data indicate an enhanced postprandial lipemia in normotriglyceridemic NIDDM patients, and demonstrate the influence of apo E polymorphism on their lipoprotein clearance. Postprandial alterations of lipoprotein remnants may thus accelerate atherogenesis even in normotriglyceridemic NIDDM patients.

Apolipoprotein AI-CIII-AIV genetic polymorphisms and coronary heart disease in type 2 diabetes mellitus

The aim of this study was to verify whether or not the increased prevalence of coronary heart disease (CHD) commonly observed in patients with type 2 diabetes mellitus is related to a genetic background involving restriction fragment length polymorphisms (RFLPs) of apolipoproteins. On the basis of a case-control design, 62 type 2 diabetic patients with CHD (confirmed by clinical history and electrocardiogram) and 62 age- and sex-matched diabetic subjects without CHD were enrolled. In each of them RFLPs of the apolipoprotein CIII gene (S1 or S2 allele) and AI promoter region (A or G allele), together with fasting plasma lipids and apolipoproteins levels, were assessed. The rare S2 allele was found significantly (P = 0.05) more frequently in patients with CHD, and its related S1S2 genotype was associated with higher plasma levels of total cholesterol (P = 0.01), triglycerides (P = 0.007) and apo B (P = 0.001) than the S1S1 genotype. The A allele was more frequent (P = 0.004) in patients without CHD and was associated with lower plasma cholesterol (P = 0.0001), low-density lipoprotein (LDL)-cholesterol (P = 0.0001) and apo B (P = 0.005). The S1/A haplotype was more frequent (P = 0.05) in patients without CHD and was associated with the lowest plasma lipid levels. These results suggest that genetic factors, related to the apo AI-CIII-AIV gene cluster, could play a role in the development of CHD in type 2 diabetic patients, probably through modification of their plasma lipid pattern.

HDLs containing apolipoproteins A-I and A-II (LpA-I:A-II) as markers of coronary artery disease in men with non-insulin-dependent diabetes mellitus

BACKGROUND

Abnormalities in HDL and an increased risk of coronary artery disease (CAD) coexist in non-insulin-dependent diabetes mellitus (NIDDM). HDLs can be separated by their apolipoprotein (apo) content into particles containing apoA-I but not apoA-II (LpA-I) and those containing both apoA-I and apoA-II (LpA-I:A-II). The LpA-I particles have been suggested to be more effective in conferring protection against CAD than the LpA-I:A-II particles. However, data are sparse, and no studies have defined the role of these two classes of particles in NIDDM.

METHODS AND RESULTS

LpA-I and LpA-I:A-II particles were quantified by a differential electroimmunoassay in four groups of men with similar age and body mass index (BMI) distributions. Group 1 consisted of 50 patients with NIDDM and angiographically verified CAD; group 2, 50 men with CAD but no diabetes; group 3, 50 men with NIDDM but no CAD; and group 4, 31 healthy men. Serum apoA-I and apoA-II concentrations were measured by immunoturbidimetry, and HDL2 and HDL3 were separated by ultracentrifugation. Concentrations of LpA-I:A-II particles in group 1 were 13.8%, 18.3%, and 26.9% lower than in groups 2 through 4, respectively. In a two-by-two factorial ANOVA, adjusted for age and BMI, the differences were significant for both CAD (P < .001) and NIDDM (P < .001), with no interaction between the factors. These results were confirmed by comparable differences in the serum concentrations of apoA-I and apoA-II. LpA-I particles were related to the presence or absence of CAD (P = .013), but the difference was lost in a multivariate analysis. A low HDL3 cholesterol concentration characterized both CAD (P = .002) and NIDDM (P = .024). HDL2 cholesterol differed significantly with regard to the presence of NIDDM (P = .033) but only borderline with respect to CAD (P = .073).

CONCLUSIONS

ApoA-II-containing lipoproteins and HDL3 cholesterol are powerful markers of CAD in men with NIDDM.

DNA polymorphisms at the locus for human cholesteryl ester transfer protein (CETP) are associated with macro- and microangiopathy in non-insulin-dependent diabetes mellitus

The effect of variation at the cholesteryl ester transfer protein (CETP) gene locus and in the apolipoprotein (apo) AI-CIII-AIV gene cluster on the susceptibility of individuals with non-insulin-dependent diabetes mellitus (NIDDM) to atherosclerotic vascular disease was studied in 136 male and 122 female patients with NIDDM. The prevalence of myocardial infarction was high (38%) in patients with the EcoNI genotype 2-2 of the CETP gene locus (= 2-2; subjects homozygous for the absence of the restriction site) compared with patients with the genotype 1-1 (= 1-1; subjects homozygous for the presence of the restriction site) (18%, p < 0.02). The prevalence of any evidence of coronary heart disease (CHD) (presence of ischaemic ECG changes or definite myocardial infarction) was high in 2-2 (73%) compared with the genotype 1-2 (= 1-2; heterozygous for the presence of the restriction site) (52%, p < 0.02) and genotype 1-1 (p = 0.06). CHD was more prevalent in men with 2-2 (70%) than in those with 1-1 (42%, p < 0.05), but in women no significant differences were found in the prevalences of CHD between the EcoNI genotypes. Neuropathy was more often present in the patients with 2-2 (31%) than in those with 1-1 (12%, p < 0.02) or 1-2 (14%, p < 0.01). Plasma total cholesterol and total- and VLDL-triglycerides were higher in women with the EcoNI genotype 1-1 than in those with the genotype 1-2. In men no significant differences in plasma lipids were found. In addition, the prevalence of cerebrovascular disease was high (21%) in the patients with the genotype 1-1 of the TaqIB polymorphism compared with the genotype 2-2 (6%, p < 0.02). None of the alleles defined by four polymorphisms in the apo AI-CIII-AIV gene region were associated with an increased risk for macroangiopathy. The PstI polymorphism had an effect on plasma triglyceride levels. At the CETP locus one pair of loci (TaqIB and EcoNI) and three pairs of loci at the apo AI-CIII-AIV gene cluster (SacI and MspI, SacI and PvuII and MspI and PvuII) showed significant allelic association. In conclusion, the variation of CETP locus modulates the risk for diabetic complications in patients with NIDDM and the effect seems to be different between men and women. In contrast, the AI-CIII-AIV gene cluster polymorphisms seem not to be related to the risk of CHD in NIDDM.(ABSTRACT TRUNCATED AT 400 WORDS)

Lipids and lipoproteins as risk factors for coronary heart disease in men with abnormal glucose tolerance: the Honolulu Heart Program

OBJECTIVES

To evaluate lipids and lipoproteins as risk factors for coronary heart disease (CHD) in older men with non-insulin-dependent diabetes (NIDDM) or abnormal glucose tolerance compared with normoglycaemic men.

DESIGN

A prospective, population-based cohort study based on the lipoprotein examination (1970-72) of the Honolulu Heart Program. Follow-up was through to December 1988.

SETTING

Honolulu, Hawaii.

SUBJECTS

Japanese-American men, ages 51-72 at baseline: 2042 with 1 h glucose < 12.5 mmol l-1 (normal group); 376 on oral hypoglycaemic agents or with 1 h glucose > or = 12.5 mmol l-1 after 50 g oral glucose challenge (abnormal glucose tolerance group). None had prevalent coronary heart disease (CHD) or stroke at baseline.

MAIN OUTCOME MEASURES

Incident CHD: definite non-fatal myocardial infarction (MI) or fatal CHD.

RESULTS

There were 221 incident cases in the normal group, and 65 in the abnormal glucose tolerance group. Total and high-density lipoprotein (HDL) cholesterol were significant predictors of incident CHD in men with NIDDM or abnormal glucose tolerance after controlling for age, body-mass index, systolic blood pressure, pack-years of cigarettes and alcohol consumption (P < 0.05). Total, low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) cholesterol were significant predictors in normal men, and HDL cholesterol was of borderline significance.

CONCLUSIONS

Abnormal lipids and lipoproteins are significant, independent predictors of CHD in subjects with NIDDM or abnormal glucose tolerance. Attention to lipid and lipoproteins as CHD risk factors should be part of clinical management of these patients.

Lipids and lipoproteins predicting coronary heart disease mortality and morbidity in patients with non-insulin-dependent diabetes

BACKGROUND

The aim of this study was to investigate the association of lipoprotein fractions with the future risk of coronary heart disease (CHD) in patients with non-insulin-dependent diabetes (NIDDM).

METHODS AND RESULTS

At baseline, lipoprotein fractions were determined in 313 diabetic patients with NIDDM (153 men and 160 women), and these patients were followed up for 7 years with respect to CHD events (CHD death or all CHD events including CHD death or nonfatal myocardial infarction). Altogether, 56 NIDDM patients (28 men and 28 women) died from CHD and 25 had a nonfatal myocardial infarction (17 men and 8 women) during the follow-up. NIDDM patients having these CHD events during the follow-up had higher levels of total and very-low-density lipoprotein (VLDL) triglycerides and VLDL cholesterol and lower levels of high-density lipoprotein (HDL) and HDL2 cholesterol than those without CHD events. The risk for CHD death was fourfold and for all CHD events, twofold higher among diabetics with low HDL cholesterol (< 0.9 mmol/L) than among diabetics with HDL cholesterol > or = 0.9 mmol/L. High triglyceride level (> 2.3 mmol/L) was associated with a twofold increase in the risk of CHD events. In multiple logistic regression analyses, HDL was inversely associated with CHD events and VLDL triglycerides with CHD events in NIDDM patients with low HDL cholesterol level (< or = 1.12 mmol/L).

CONCLUSIONS

Our 7-year follow-up study gives evidence that low HDL and HDL2 cholesterol, high VLDL cholesterol, and high total and VLDL triglycerides are powerful risk indicators for CHD events in patients with NIDDM:

Relation of coronary heart disease and apolipoprotein E phenotype in patients with non-insulin dependent diabetes

OBJECTIVES

To examine the relation between coronary heart disease and the apolipoprotein E phenotypes in patients with non-insulin dependent diabetes mellitus.

DESIGN

Cross sectional study.

SETTING

District around Kuopio University Central Hospital, East Finland.

SUBJECTS

138 men with non-insulin dependent diabetes and 64 men without diabetes as controls.

MAIN OUTCOME MEASURE

Apolipoprotein E phenotype, electrocardiographic abnormalities, other signs of coronary heart disease.

RESULTS

The prevalences of definite myocardial infarction and ischaemic electrocardiographic changes were highest in the diabetic men with the phenotypes E4/4 or E4/3 (25% (95% confidence interval 18% to 32%) and 50% (42% to 58%) respectively), although the difference between the phenotype groups was not significant. The prevalence of angina pectoris was 69% (61% to 77%) in men with the phenotypes E4/4 or E4/3 (p = 0.005 compared with other phenotypes), 41% (33% to 49%) in men with phenotype E3/3, and 47% (39% to 55%) in those with phenotypes E2/2 or E2/3. Similarly, the simultaneous presence of angina pectoris and ischaemic electrocardiographic changes was highest in the diabetic men with the phenotypes E4/4 or E4/3 (42% v 22% in those with E3/3 and 29% in those with E2/2, E2/3; p = 0.038). Overall, the prevalence of any evidence of coronary heart disease among the diabetic subjects with the phenotypes E4/4 or E4/3 was 81% (p = 0.011 compared with other phenotypes), 58% in those with phenotype E3/3, and 53% in those with phenotypes E2/2 or E3/3.

CONCLUSION

Apolipoprotein E phenotypes E4/4 and E4/3 modulate the risk of coronary heart disease in men with non-insulin dependent diabetes.

A prospective study of cholesterol, apolipoproteins, and the risk of myocardial infarction

BACKGROUND

The independent contributions of subfractions of high-density lipoprotein (HDL) cholesterol (HDL2 and HDL3) and apolipoproteins in predicting the risk of myocardial infarction are unclear. Prospective data are sparse, but HDL2 is widely believed to be a more important predictor than HDL3.

METHODS

Blood samples were collected at base line from 14,916 men (ages, 40 to 84 years) who were participants in the Physicians' Health Study. After five years of follow-up, plasma samples from 246 men with new myocardial infarction (case subjects) were analyzed together with specimens from 246 men matched to them for age and smoking status who had not had a myocardial infarction.

RESULTS

The levels of total cholesterol and apolipoprotein B-100 were significantly associated with an increased risk of myocardial infarction (data on levels of low-density lipoprotein cholesterol were unavailable). Both HDL cholesterol and HDL2 levels were associated with a substantially decreased risk of myocardial infarction, but the HDL3 level was the strongest predictor; the relative risk was 0.3 (95 percent confidence interval, 0.2 to 0.6) for those in the fifth of the group with the highest HDL3 levels, as compared with the fifth with the lowest levels. The benefit of a higher HDL cholesterol level was most pronounced among those with lower total cholesterol levels. Levels of apolipoprotein A-I and apolipoprotein A-II were also associated with decreased risk. However, the levels of HDL subfractions and apolipoproteins did not add significantly to the value of a multivariate model that included the ratio of total to HDL cholesterol in predicting myocardial infarction, whereas that ratio remained a significant independent predictor of risk. After adjustment for other risk factors, a change of one unit in the ratio of total to HDL cholesterol was associated with a 53 percent change in risk (95 percent confidence interval, 26 percent to 85 percent).

CONCLUSIONS

This study underscores the importance of HDL cholesterol in predicting the risk of myocardial infarction and demonstrates protective effects of both the HDL3 and HDL2 subfractions of HDL cholesterol. We found little or no predictive value for the levels of apolipoproteins A-I, A-II, and B or HDL subfractions after conventional risk factors and the ratio of total to HDL cholesterol were considered.

DNA restriction polymorphisms of the apolipoprotein AI-CIII-AIV gene cluster: a genetic determinant of atherosclerosis in type 2 (non-insulin-dependent) diabetes mellitus

The presence of polymorphic restriction sites (S2, M2, P2) of the apolipoprotein AI-CIII-AIV gene cluster for the respective Sst1, Msp1, and Pst1 enzymes was assessed after hybridization with a radiolabelled apolipoprotein AI gene probe in 64 Type 2 diabetic patients and 67 healthy control subjects, all Europids. Twenty-two diabetic patients showed evidence of ischaemic heart disease or macrovascular arteriopathy and forty-two were free of cardiovascular complications. Control subjects were selected for the absence of personal or familial metabolic or cardiovascular diseases. The frequencies of polymorphic alleles were in agreement with previous studies in the control group: S2 6.3 (95% confidence interval (CI) 2.3-10.3) %, M2 5.5 (1.6-9.4) %, P2 6.3 (2.3-10.3) % and did not differ in the whole diabetic group: S2 4.2 (0.7-7.7) %, M2 6.5 (2.0-11.0) %, P2 6.6 (2.3-10.9) %. The relative prevalences of S2, M2, and P2 alleles were, respectively: 3.32, 1.54, and 2.00 (Woolf's ratio) in the macroangiopathic group but allele distribution frequencies were not statistically different from non-macroangiopathic patients. The allelic associations S2M2P1 and S1M1P2 showed a relative prevalence of 2.86 and 2.00 in the presence of cardiovascular complications but the difference was not significant in terms of polyallelic distribution frequencies in the absence of atherosclerosis. No serum lipid abnormalities could be related to the presence of any polymorphic allele or allelic association. These results suggest a genetic influence on the development of atherosclerosis in Type 2 diabetes, but the mechanism remains unclear.

Hyperlipidaemia in diabetes

Currently our knowledge of the role of lipid abnormalities as risk factors for CHD in diabetes is insufficient. We need to define exact risk parameters to target correctly the therapy of lipid disorders and to outline optimum therapeutic strategies. Therefore it is necessary to identify quantitative and qualitative abnormalities of lipoproteins and apoproteins which signify the risk of CHD and to define their predictive power in prospective trials. Obviously we need to know more about the pathophysiology of lipid abnormalities and the action of insulin. Because diabetic patients carry a high inherent risk of CHD, target values recommended for non-diabetic populations may not be optimal for diabetic populations, but should be lower. To date no primary or secondary intervention trials in diabetic populations have been carried out to show that the lowering of lipid values (serum and LDL cholesterol) will reduce the risk of CHD morbidity or mortality or will prevent the progression of CHD in diabetes. Since hypertriglyceridaemia and low HDL levels are typical abnormalities in NIDDM it is a unique target group to test whether lowering of triglycerides and raising of HDL cholesterol levels will reduce the risk of CHD. Therefore there is a pressing need for clinical trials in both IDDM and NIDDM to provide adequate information on the benefits of lipid-lowering therapy and to confirm treatment strategies.

Association of plasma triglyceride and C-peptide with coronary heart disease in Japanese-American men with a high prevalence of glucose intolerance

In a community-based study of second-generation Japanese-American men known to have a high prevalence of both Type 2 (non-insulin-dependent) diabetes and impaired glucose tolerance, there was a highly significant association of coronary heart disease with glucose intolerance in a study sample of 219 men. Intra-abdominal cross sectional fat area determined by computed tomography was significantly elevated in men with coronary heart disease even after adjustment for glucose intolerance and body mass index (p = 0.026). Other differences that were significantly related to coronary heart disease after adjustment for glucose intolerance were lower high density lipoprotein cholesterol levels (p = 0.001), elevated total triglyceride and very low density lipoprotein triglyceride (p less than 0.001), and elevated fasting insulin and C-peptide levels p = 0.001. When these variables were tested in a stepwise multiple logistic regression model, significant independent associations with coronary heart disease were found only for total triglyceride and fasting C-peptide after adjustment for glucose tolerance status. Variables identified to be associated with coronary heart disease were interpreted as representing or manifesting an insulin resistant state. Thus, insulin resistance may be the underlying risk factor aetiologically linking glucose intolerance with coronary heart disease.

Fish oil: a panacea?

Since the first report by Bang and Dyerberg regarding the apparent beneficial effects of a fish oil-enriched diet on the incidence of atherosclerotic heart disease in Greenland eskimos, a considerable number of studies have been performed regarding the effects of omega-3 polyunsaturated fatty acids on the prevention and treatment of a variety of disease states not necessarily related to atherosclerosis. Studies have been performed on healthy volunteers and in patients with hyperlipidaemia, atherosclerotic vascular disease, diabetes, asthma, psoriasis and chronic renal insufficiency, amongst others. Positive effects on platelet activity, lipid profile, blood rheology and blood pressure--all factors which are presumably of importance in the pathogenesis of atherosclerotic disease have been noted in these studies, albeit with a wide range of variability. Some negative effects also appear to exist. However, some general conclusions can be made regarding the effects of a fish oil-enriched diet.

Treatment of lipid disorders in diabetes mellitus

One reason for premature atherosclerosis in patients with diabetes mellitus is abnormal lipid metabolism. This article discusses the plasma lipid disorders associated with diabetes mellitus, and how to apply the new guidelines from the National Cholesterol Education Program for treatment of hypercholesterolemia in patients with diabetes mellitus.

Lipoprotein pattern in long-term diabetes of an at least 35 years' duration. Results of the Erfurt Study

All diabetic patients suffering from the disease for at least 20 years and living in the closed area of the Erfurt district in 1970 have been followed prospectively since that time. In 47 of them still alive in 1985, i.e. after more than 35 years of diabetes, serum lipid and apolipoprotein concentrations were measured and compared to those of non-diabetic subjects without cardiovascular diseases (n = 47) pair-matched by sex, age, and body weight. In males (n = 27) significantly (p less than 0.01) higher levels of HDL cholesterol and apolipoprotein A-I as well as lower concentrations of triglycerides and a lower total cholesterol/HDL cholesterol risk ratio than in nondiabetic control subjects could be found. In long-term diabetic females (n = 20), apolipoprotein A-I levels were also increased (p less than 0.02). Trends in HDL cholesterol and triglycerides were similar to those found in males but did not reach statistical significance. Higher concentrations of total cholesterol (p less than 0.02), LDL cholesterol (P less than 0.05), and apolipoprotein B (p less than 0.02), however, did not fit in with a beneficial lipoprotein pattern. The frequency of pathological lipoprotein patterns was not higher than among the non-diabetic control subjects (32% and 40%, respectively). According to these findings an antiatherogenic lipoprotein pattern might be considered, at least in males, as one of the determinants causing the multifactorial event of long-term survival in diabetes.

Insulin treatment of non-insulin-dependent diabetes mellitus

The standard treatment of NIDDM consists of diet, oral hypoglycaemic agents and, mostly as a last resort, insulin. Indications for insulin therapy cannot be generalized for the whole population of NIDDM patients. The defined objectives of therapy for the individual patient will determine the choice and intensity of therapy. These will usually be either a relief of hyperglycaemic symptoms in the elderly patient or normoglycaemia, as in the insulin-dependent diabetic patients, in order to prevent acute and chronic complications. Primary insulin treatment is advisable in patients with hyperglycaemic symptoms and fasting blood glucose levels above 15 mmol/l, as in these patients the major defect will be insulin deficiency rather than insulin resistance. The correction of long lasting hyperglycaemia partly restores insulin sensitivity and B cell function, thereby allowing sequential reduction of insulin dosage. When metabolic control can be sustained with low insulin dosages some of these patients may later respond well to oral hypoglycaemic agents or to diet alone. In the management of non-insulin-dependent diabetic patients it is of great importance to recognize in time when treatment with oral hypoglycaemic agents fails. Insulin therapy should not be withheld on the presumption that it will cause weight gain and will promote development of macrovascular disease. Weight gain can be reduced by adequate dietary counselling and the level of macrovascular risk factors reduces with improved metabolic control. In this context also it should be realized that the correction of hypertension, hyperlipidaemia and the cessation of cigarette smoking is probably of equal importance. Insulin therapy regimens which have been used in non-insulin-dependent diabetic patients have been the same as prescribed for insulin dependent patients. When considering the fact that hepatic overproduction of glucose is the major determinant of fasting blood glucose level and that postprandial glycaemic excursions are superimposed on this level it seems reasonable to aim for normalization of the basal hepatic glucose production. A bedtime injection of an intermediate or long acting insulin can be used for this aim. Other therapeutical approaches which have been studied recently are the use of combinations of insulin and oral hypoglycaemic agents and the use of proinsulin as an alternative for intermediate acting insulin. Before these forms of therapy can be advocated long-term clinical studies are necessary to define their therapeutic role.

Diabetes and atherosclerosis: an epidemiologic view

Diabetes is associated with changes in plasma lipids and lipoproteins into atherogenic direction. In IDDM these changes are small or absent if good metabolic control can be maintained. Diabetic nephropathy is, however, associated with the appearance of dyslipoproteinemia. In NIDDM plasma total and VLDL triglyceride levels are elevated, and HDL-cholesterol level is decreased, and this pattern of dyslipoproteinemia does not always respond to improved control of hyperglycemia. Abnormalities of lipoprotein metabolism, not reflected in conventional plasma lipid and lipoprotein level measurements, and glucosylation of lipoproteins and resulting alterations in lipoprotein catabolism may be of importance in the enhanced atherogenesis in diabetes. Both IDDM and NIDDM are associated with an increased frequency of hypertension, but the underlying mechanisms appear to be different. In IDDM hypertension is usually associated with the development of diabetic nephropathy and thus with a long duration of the disease. In NIDDM hypertension is often present already at the time of diagnosis, and also in IGT, the precursor stage of NIDDM, the prevalence of hypertension is already increased. Obesity explains only in part the high prevalence of hypertension in patients with NIDDM. Diabetes is known to be associated with multiple abnormalities in hemostatic factors and, although these abnormalities may contribute importantly to the increased risk of ASVD in diabetic patients, information about their real role is scanty and conflicting. The impact of general major risk factors for ASVD, elevated plasma cholesterol, elevated blood pressure, and smoking, on the risk of ASVD appears to be similar in diabetics and nondiabetics. Only a relatively small proportion of the excessive occurrence of ASVD in diabetics can, however, be explained by the effects of diabetes on the levels of general risk factors for ASVD. This proportion mediated through the effects of diabetes on risk factors is larger in female diabetics than in male diabetics. The major proportion of the excess of ASVD in diabetics remains, however, unexplained and must be due to effects of diabetes itself through mechanisms that are incompletely understood.

The relationship of cardiovascular risk factors to the prevalence of coronary heart disease in newly diagnosed type 2 (non-insulin-dependent) diabetes

The relationship of cardiovascular risk factors to the prevalence of coronary heart disease was examined in 133 newly diagnosed Type 2 (non-insulin-dependent) diabetic patients (70 men, 63 women) aged from 45 to 64 years and in 144 randomly selected non-diabetic control subjects (62 men, 82 women) of the same age. The prevalence of coronary heart disease in diabetic patients, defined by symptoms and ischaemic ECG abnormalities in resting or exercise ECG, was more than threefold that in non-diabetic subjects. In multiple logistic analyses (including age, history of smoking, hypertension (+/-), serum cholesterol, HDL-cholesterol, triglycerides, 2-h post-glucose serum insulin, body mass index and diabetes (+/-] carried out separately for men and women, diabetes showed an independent, significant association to coronary heart disease in both sexes. In addition, age and hypertension had a borderline association to coronary heart disease in men, whereas smoking and high 2-h post-glucose serum insulin level showed a significant association in women.