Age differences in phagocytosis by polymorphonuclear leukocytes measured by flow cytometry.

Elderly persons have increased morbidity and mortality due to bacterial infections. Since the polymorphonuclear leukocyte (PMN) is a major defense against bacterial infection, we utilized fluorescent microspheres and flow cytometry to examine phagocytosis by PMNs from 55 young and middle-aged adults (mean age 41.5 yrs) and two groups of elderly subjects: one group of 35 healthy individuals (mean age 74.1 years) living at home, and a second group of 11 residents (mean age 83.1 years) with severe mental and physical disabilities, living in a domiciliary care facility. We determined the percent phagocytic PMNs, the number of microspheres per PMN, and the number of microspheres per 100 PMNs. The mean number of microspheres per phagocytic PMN was similar for all groups. Statistically significant differences were found between the young and middle-aged group and the healthy or ill elderly groups for the percent phagocytic PMNs (75.3% vs 51.5% and 43.8%), and the number of microspheres per 100 phagocytic PMNs (197.3 vs 131.4 and 103.2). There were no significant differences in these parameters between healthy and debilitated elderly subjects. These data document that there is an age-related increase in representation of a population of PMNs which have a defect in phagocytic ability.

Role of body fat distribution in the decline in insulin sensitivity and glucose tolerance with age.

The relationships of body composition and physical fitness [maximal aerobic capacity (VO2max)] to the decline in insulin sensitivity with age were examined in healthy older (47-73 yr; n = 36) and young (19-36 yr; n = 13) men. In 18 older men with normal glucose tolerance (OGTT), glucose disposal rates (M) during hyperinsulinemic euglycemic clamps correlated negatively with the waist to hip ratio (WHR; r = -0.77; P < .001) and percent body fat (r = -0.46; P < 0.05) and positively with VO2max (r = 0.54; P < 0.05), but not with age. Similar relationships existed in the 36 older men with a spectrum of OGTT responses; however, only WHR was independently related to M (r2 = 0.32; P < 0.01). In the older men with normal OGTT, M (mean +/- SEM, 7.88 +/- 0.43 mg/kg fat-free mass.min) was not different from that in the young men (8.56 +/- 0.47; P = NS). Furthermore, in older and young men with normal OGTT matched for WHR, percent fat, or VO2max, glucose disposal was comparable at sequential 15-min intervals during the clamp and in its relationship to insulin concentrations at the tissue level (multicompartmental analysis). In contrast, despite higher steady state plasma insulin levels during the clamp, M was significantly lower in the older men with a higher WHR, greater percent fat, lower VO2max, or impaired OGTT. Thus, in healthy older men up to the age of 73 yr, insulin sensitivity and glucose tolerance are affected primarily by the regional body fat distribution, not age, obesity, or VO2max.

Non-insulin-dependent diabetes mellitus in the elderly. Influence of obesity and physical inactivity.

The development of hyperglycemia in the elderly is often multifactorial in etiology, and its presentation is often confounded by the advanced age of the patient, the presence of coexisting diseases and altered mental states, the absence of symptoms, and physical conditions specific to the medical care of the geriatric patient. Manifestations of macro- and microvascular complications of non-insulin-dependent diabetes mellitus (NIDDM) often herald the disease in the elderly, yet there is incomplete knowledge of the natural history of the disease and poor guidelines for its effective management in the geriatric population. Once NIDDM is diagnosed in the older patient, the propensity for these patients to develop atherosclerotic vascular complications involving every organ system and the socioeconomic sequela of the disease make treatment prudent. Coexisting risk factors for atherosclerosis, such as dyshypoproteinemia, hypertension, obesity, and cigarette smoking, should be treated vigorously, and poor diet, physical inactivity, and medications affecting glucose tolerance modified. Hyperglycemia resistant to nonpharmacologic therapy should be treated with second-generation oral sulfonylureas, and the judicious use of insulin is advised because of a heightened risk for the hazards of hypoglycemia in the elderly. The treatment of NIDDM has important implications in the elderly because of its prevalence and its association with other age-related pathophysiologic processes. Such effective treatment may have the potential to reduce morbidity and mortality and improve the quality of life of older people.

The effects of single and sequential insulin infusions on glucose disposal in older men.

The hyperinsulinemic euglycemic glucose clamp is widely used to quantitate in vivo insulin action. Modification of this technique by sequentially infusing multiple doses of insulin allows determination of insulin sensitivity and maximal responsiveness; however, the validity of this approach has not been determined in older individuals. In this study, glucose disposal rates during a sequential three-dose clamp at insulin infusion rates of 20, 100, and 500 mU/m2.min were compared to those obtained during a single-dose 100 mU/m2.min clamp in eight healthy older men. There were no differences in plasma insulin levels (256 +/- 46 vs. 261 +/- 32 microU/ml) or glucose disposal rates (11.0 +/- 3.6 vs. 10.8 +/- 3.0 mg/kgfat-free mass.min) during the 100 mU/m2.min infusion of the three-dose clamp and the one-dose clamp. In four subjects with impaired glucose tolerance, the EC50 (insulin concentration producing a half-maximal response) was higher and Mmax (maximal glucose disposal) lower than in subjects with normal glucose tolerance, suggesting impairments in both insulin sensitivity and responsiveness in older subjects with impaired glucose tolerance. Future studies using this modification of the hyperinsulinemic euglycemic glucose clamp to determine insulin sensitivity and responsiveness may lead to an improved understanding of the insulin resistance of aging and the pathogenesis of diseases such as diabetes and hypertension.

The role of obesity and cardiovascular fitness in the impaired glucose tolerance of aging.

The prevalence of impaired glucose tolerance (IGT) increases with aging. Although some data suggest that age is independently associated with IGT, other studies suggest that age-associated changes in body composition and reduced cardiovascular fitness are responsible for the development of IGT. We, therefore, examined the relationship of age, total and regional adiposity, and level of fitness (VO2max) to the presence of IGT in 155 healthy, nondiabetic, nonsmoking, older community dwelling men. Sixty-two of 155 men (40%) had IGT, while 93 men (60%) had normal glucose tolerance (WHO criteria). The subjects with IGT were of similar age (61.0 +/- 1.0 vs. 59.0 +/- 0.7 years, p = 0.49) and had the same maximal aerobic capacity, (VO2max) (42.0 +/- 1.0 vs. 44.0 +/- 0.8 mL/kg ffm/min, p = 0.42), but had a higher waist to hip ratio (WHR) (0.98 +/- 0.01 vs. 0.96 +/- 0.01, p = 0.005) and percent body fat (30.0 +/- 0.4 vs. 26.0 +/- 0.6, p = 0.004) than the men with normal glucose tolerance. In univariate analysis, the 2-h glucose level correlated positively with percent body fat (r = 0.30, p = 0.0002), WHR (0.24, p = 0.002), and age (r = 0.17, p = 0.03) and negatively with VO2max (r = -0.23, p = 0.005). In both multiple logistic and linear regression analyses, percent body fat was the only independent predictor of IGT (p = 0.002). These results suggest that the age-associated increase in total adiposity is a major contributor to the development of IGT in middle-aged and older men. Thus, lifestyle modifications that reduce body fat should reduce the risk for IGT and the development of noninsulin-dependent diabetes mellitus in the elderly.

Short-term outcomes of elderly patients discharged from an emergency department.

To determine the short-term functional and medical outcomes and predictors of outcome following discharge from an acute hospital emergency department, 100 elderly (greater than or equal to 65 yr) and 100 nonelderly (less than 65 yr) patients were studied prospectively. Patients were interviewed at three days and again at three weeks following emergency department discharge. The number of new prescriptions given to both groups in the emergency department was similar (elderly 41%; nonelderly, 31%). The elderly were as likely as the nonelderly to know the correct name (elderly, 88%; nonelderly, 87%), dosage schedule (elderly, 90%; nonelderly, 90%) and purpose (elderly, 85%; nonelderly, 94%) of their new medications. There was no difference in patients' understanding of the diagnosis (elderly, 72%; nonelderly, 72%) or in medication compliance (elderly, 81%; nonelderly, 74%). Elderly patients were more likely to keep scheduled follow-up appointments (87% vs 65%; P less than .05). Despite these similarities the elderly had worse medical outcomes at three weeks; 67% of the elderly were better and 20% were worse, including seven patients who required interim hospitalization, four of whom died. In contrast, 82% of the nonelderly were better and only 4% were worse (P less than .01). None of the nonelderly required hospitalization or had died. Functional impairments were more common in the elderly both at baseline (elderly, 26%; nonelderly, 6%; P less than .01) and at three weeks (elderly, 27%; nonelderly, 5%; P less than .001). Independent predictors of poor medical outcome included age greater than or equal to 65 (P less than .009) and functional impairment at baseline (P less than .022).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of an American Heart Association step I diet and weight loss on lipoprotein lipid levels in obese men with silent myocardial ischemia and reduced high-density lipoprotein cholesterol.

Reduced plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are a risk factor for coronary artery disease (CAD). In this study, we examined the sequential effects of an isocaloric American Heart Association (AHA) step I diet and a hypocaloric AHA step I diet (AHA step I diet + weight loss) on lipoprotein lipid levels in 14 middle-aged and older (60 +/- 6 years, mean +/- SD) obese (body mass index [BMI] > 27 kg/m2) nondiabetic men with exercise-induced silent myocardial ischemia (SI) and reduced HDL-C levels (0.85 +/- 0.14 mmol/L). Nine men of comparable age and obesity and with no evidence of exercise-induced ischemia that were evaluated longitudinally served as metabolic controls. In men with SI, after 3 months on the isocaloric AHA step I diet plasma triglyceride (TG) levels decreased by 26% (2.25 +/- 0.66 to 1.67 +/- 0.69 mmol/L, P < .005), cholesterol by 12% (5.24 +/- 0.84 to 4.62 +/- 0.78 mmol/L, P < .01), and low-density lipoprotein cholesterol (LDL-C) by 10% (3.40 +/- 0.69 to 3.05 +/- 0.70 mmol/L, P < .01). However, plasma HDL-C levels also decreased by 7% (0.85 +/- 0.14 to 0.79 +/- 0.13 mmol/L, P < .05). Subsequent weight loss (11 +/- 4 kg) in conjunction with the AHA step I diet resulted in an additional decrease of 24% in TG (P < .005), 10% in cholesterol (P < .05), and 10% in LDL-C (P < .05). Plasma HDL-C levels increased by 8% (P < .01), thereby correcting the decline seen on the AHA step I diet alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Time course of plasma free fatty acid concentration in response to insulin: effect of obesity and physical fitness.

This study examines the relationships between parameters of the time course of plasma free fatty acid (FFA) concentration during a euglycemic, hyperinsulinemic clamp (100 mU/m2.min) and the age, body composition, and physical fitness, indexed as maximal aerobic capacity (VO2 max), of three groups of healthy men: (A) 20 obese older men (32% +/- 1% fat, aged 60 +/- 2 years, mean +/- SEM); (B) 11 lean older men (19% +/- 1% fat, aged 63 +/- 2 years); and (C) 11 lean younger men (16% +/- 2% fat, aged 27 +/- 2 years). The time course was modeled as a delayed exponential decline from an initial level to a plateau level. The plateau level was 72% +/- 2%, 72% +/- 2%, and 68% +/- 3% of the initial level in groups A, B, and C, respectively. The delay was shorter in the younger men than in the older men (7.6 +/- 0.9 minutes in group C v 13.2 +/- 1.0 in group A and 11.9 +/- 1.6 minutes in group B), but correlated more strongly with percent fat, waist to hip ratio (WHR), or VO2max than with age. The magnitude of the rate constant of the exponential, k, was smaller in obese than in lean men (3.2 +/- 0.2 h-1 in group A v 5.3 +/- 0.6 h-1 in group B and 6.4 +/- 0.6 h-1 in group C), and was independently predicted only by percent fat in the older men and only by VO2max when the older and younger groups were combined.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of weight loss by diet alone or combined with aerobic exercise on body composition in older obese men.

The effects of weight loss induced by hypocaloric diet (HD) alone or combined with aerobic exercise (AEX+HD) on body composition were compared in 61 sedentary obese men aged 60.6 +/- 1.0 years (mean +/- SEM). Twenty-three subjects in the AEX+HD intervention and 28 subjects in the HD intervention lost a similar amount of body weight (range, 3 to 22 kg). Fifteen men underwent no intervention and served as controls (CON). All groups were of similar body composition at baseline. The HD group decreased caloric intake for 10 months, whereas the AEX+HD group combined HD with AEX (3 times per week) for 10 months. The HD and AEX+HD groups had significant and comparable reductions in body weight (9.3 +/- 0.8 v 8.1 +/- 0.6 kg), fat mass (6.8 +/- 0.5 v 6.7 +/- 0.5 kg), and fat-free mass (2.1 +/- 0.3 v 1.3 +/- 0.3 kg; all P < .05). None of the variables changed significantly in the CON group. Regression lines depicting the relationship between the loss in fat-free mass and the decrease in body weight did not differ significantly in either slope or intercept between the treatment groups. These results suggest that in older obese men, hypocaloric dieting combined with AEX training does not attenuate the loss in fat-free mass that occurs during weight loss by hypocaloric dieting alone.

Effects of weight loss on norepinephrine and insulin levels in obese older men.

Older individuals have higher plasma insulin and norepinephrine (NE) levels than the young. This may be due to biological aging; however, these changes also may be due in part to the increase in abdominal obesity that often accompanies aging. The latter possibility was tested by examining the effects of weight loss on plasma insulin and NE levels in 11 healthy men aged 52 to 72 years who had mild to moderate obesity (body mass index [BMI], 27 to 36 kg/m2). Plasma insulin levels were measured during an oral glucose tolerance test, and on a second day NE levels were measured during supine rest and upright posture. Subjects lost 10 +/- 5 kg (mean +/- SD) and decreased their waist to hip ratio ([WHR] an index of the pattern of regional fat distribution) 2.8% (P < .01) over 9 +/- 3 months through mild caloric restriction. This resulted in a 23% decrease (P < .05) in fasting insulin levels and a 48% decrease (P < .01) in 2-hour insulin levels. Weight loss also resulted in a 31% decrease (P < .001) in supine plasma NE levels and an 8% decrease (P < .05) in supine diastolic blood pressure (BP). Decreases in supine plasma NE levels correlated with changes in WHR (r = .61, P < .05), but did not correlate with changes in other measures of body composition or with changes in glucose and insulin levels. These results suggest that higher plasma NE levels are related to the distribution of body fat to upper-body or abdominal sites in obese older men.

Effects of body composition and exercise capacity on glucose tolerance, insulin, and lipoprotein lipids in healthy older men: a cross-sectional and longitudinal intervention study.

The relationships of age, body composition, and physical conditioning status to glucose tolerance, insulin, and lipoprotein levels were examined in 77 healthy, nonsmoking white male volunteers, aged 46 to 73 years with no evidence of coronary artery or endocrine-metabolic disease. The men had a wide range of body fat (13% to 39%), indexed as waist-to-hip ratio (WHR, 0.84 to 1.08), and maximal aerobic capacity (VO2max, 17 to 48 mL/kg.min). Multiple regression analysis with age, VO2max, WHR, and percent body fat as independent variables demonstrated that fasting plasma insulin, triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) levels were independently related to both percent body fat and WHR. In contrast, fasting plasma glucose levels and insulin responses during oral glucose tolerance tests (OGTT) correlated independently with percent body fat, and glucose responses to OGTT correlated only with WHR. Although fasting plasma TG and HDL-C correlated with glucose and insulin levels, in multiple regression analyses only percent body fat and WHR were the significant independent variables. Fasting total and low density lipoprotein cholesterol values were not related to these variables. To test the effects of weight loss and exercise training on these relationships, 20 obese men of comparable age, percent body fat, WHR, and VO2max were randomly assigned to weight loss or aerobic exercise training programs. A 12% +/- 3% loss in body weight (P less than .01, mean +/- SD) resulted in a 19% +/- 9% decline in body fat (P less than .01) with no change in fat free mass, WHR, or VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparable effects of diet and exercise on body composition and lipoproteins in older men.

Changes in body composition, fat distribution and lipoprotein lipids in response to weight loss elicited by a 10-month program of hypocaloric diet (HD) therapy alone or combined with aerobic exercise training (AEX+HD) were examined in sedentary obese older males. Body composition was assessed by hydrodensitometry and fat distribution was evaluated with skinfold thickness and circumference measures. The HD group underwent a dietary/behavioral modification program to reduce caloric intake. The AEX+HD group underwent a similar dietary modification program combined with aerobic exercise training. Following completion of the study, 15 subjects from each group were individually pair matched based on age (57.1 +/- 1.7 vs 61.3 +/- 2.4 yrs) and their reduction in body mass (-7.6 +/- 1.3 vs -8.0 +/- 1.1 kg). Reductions in fat and fat-free mass and skinfold thickness and circumferences were similar in both groups. In both the AEX+/HD and HD groups there were significant reductions in the ratio of low-density lipoproteins to high-density lipoproteins (HDL-C) and triglycerides and a significant increase in HDL2-C. There were no differences in final values or absolute and relative changes in the various lipoprotein values between the two groups. These results suggest weight loss induced by diet alone or combined with aerobic exercise cause similar changes in body composition and lipoprotein lipids.

Persistence of low HDL-C levels after weight reduction in older men with small LDL particles.

LDL subclass pattern B is characterized by a predominance of small LDL particles (LDL peak particle size < or = 255 A) and is associated with increased plasma triglyceride (TG) and reduced HDL cholesterol (HDL-C) concentrations. This study compared the effect of weight loss on lipoprotein and glucose metabolism in 15 healthy, obese (body mass index [BMI], 30.9 +/- 2.4 kg/m2), older (60 +/- 9 years) men with LDL pattern B and in 25 men of comparable age and BMI with LDL pattern A (LDL peak particle size > or = 260 A). At baseline, men with LDL pattern B had higher TG and lower apolipoprotein (apo) A-I, HDL-C, and HDL2-C levels (P < .001) than men with LDL pattern A, while the total cholesterol and LDL cholesterol levels and fasting and 2-hour postprandial glucose and insulin levels did not differ between groups. With weight loss (10.1 +/- 3.6 kg) there were significant decreases in 2-hour postprandial glucose and insulin levels in men with LDL patterns B and A (P < .05). However, the change in plasma TG, HDL-C, HDL2-C, and apoA-I levels with weight loss differed between groups. In men with LDL pattern A, plasma TG levels decreased by 15% (P < .001) compared with a 34% (P < .001) decrease in LDL pattern B (two-factor ANOVA, P < .01). Plasma HDL-C concentrations increased by 0.16 mmol/L (P < .001) in the men with LDL pattern A but by only 0.07 mmol/L in the men with LDL pattern B (two-factor ANOVA, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of obesity and physical fitness to cardiopulmonary and metabolic function in healthy older men.

The relationship of obesity and physical fitness (VO2max) to cardiopulmonary and metabolic function was examined in 132 healthy obese, nonsmoking men age 45-79. Obese men with higher VO2max had lower % body fat and waist-to-hip ratio (WHR) than obese men with low VO2max. The obese subjects with high WHR (upper body fat distribution) had higher systolic blood pressure, hyperinsulinemia and impaired glucose tolerance, lower high density lipoprotein cholesterol (HDL-C), and higher triglyceride (TG). VO2max (ml/kg FFM.min) was lower in the older men (r = -0.54, p less than .001), and 32% of the variation was accounted for by age and the one-second forced expiratory volume. Although pulmonary function was normal, 50% of the variability was predicted by age, height, and VO2max or WHR. Glucose tolerance and insulin correlated better with VO2max and indices of body composition than with age, while plasma TG and HDL-C correlated with body composition, not VO2max or age. Thus, while age affects the cardiopulmonary and metabolic function of obese older men, physical inactivity, obesity, and an abdominal body fat distribution (increased WHR) contributed significantly to their reductions in physiological function.

Patterns of use of the emergency department by elderly patients.

The spectrum of illness and use patterns of 540 elderly patients (greater than or equal to 65 years) admitted to an emergency department (ED) were compared to an equal number of nonelderly patients. The proportion of visits by the elderly group to the ED was similar to the proportion of elderly residents in the area surrounding the hospital. Elderly patients were more likely than nonelderly patients to have an emergent diagnosis (34.4 vs. 8.3%), to arrive by ambulance (54.6 vs. 23.5%), to be admitted to the hospital (51.1 vs. 14.4%), and to have a medical (as opposed to a surgical) illness (75.0 vs. 53.2%). The spectrum of diseases was different between the two groups. Elderly patients had a higher proportion of cardiac (28.4 vs. 7.2%) and pulmonary disease (5.3 vs. 2.8%). Nonelderly patients had more injuries (30.5 vs. 10.7%) and self-limited infectious disease (11.5 vs. 5.0%). The proportion of psychiatric disease and social problems was low in both groups, about 5%. Elderly patients had a significantly lower proportion of nonurgent diagnoses (19.4 vs. 32.0%) than the nonelderly patients. Use of the ED by elderly patients is different from nonelderly patients in that they are more likely to have a serious medical illness. There is little evidence that elderly persons use the ED for primary self-care or social problems.

Studies in the distribution of body fat: I. Effects of age, sex, and obesity.

The pattern of body fat distribution has been shown to be related to a large number of variables of clinical importance. A variety of indices have been devised, many of them simple enough to be useful in large-scale clinical studies. Relationships among these several indices and systematic information on the effects of age, sex, and obesity have, however, not been systematically studied. Five anthropometric ratios that classify individuals into different body types have been computed for 1179 men and women aged 17-96 years. These are: waist hip ratio, arm thigh ratio, waist thigh ratio, waist arm ratio, and subscapular triceps skinfold ratio. In general, the age patterns show progressive trends toward increasing upper and central body fat deposition with age. In women there tends to be a postmenopausal acceleration of this trend. The ratios are distinctly higher in men than in women and are also independently influenced by the body mass index. Predictive equations that take age and BMI into account for each of the indices for men and women have been provided.

Studies in the distribution of body fat. II. Longitudinal effects of change in weight.

Information on the effects of age, sex, obesity and weight change on the fat distribution pattern has not been systematically reported. As an index of body fat distribution, the waist hip circumference ratio (WHR) was computed in 370 men and 177 women aged 22-86 years, participants of the Baltimore Longitudinal Study of Aging. For cross-sectional analysis, initial data on the participants were analyzed; for longitudinal study, the changes in the measurements related to weight change during a 5-year follow-up were analyzed. From cross-sectional analysis: (1) waist circumference is larger in men than in women and increases progressively with age; (2) hip circumference shows no consistent age or sex differences; (3) thus, the well known sex differences in WHR are totally attributable to differences in waist circumference; (4) increases in WHR with age occur in both men and women. From longitudinal analysis of weight change: (1) changes in waist and hip circumferences are correlated directly with changes in weight in both sexes, but there are large differential sex effects; (2) in men, waist changes dominate; (3) in women, waist and hip changes are nearly the same; (4) thus, weight changes in men have large effects on the WHR, while in women changes in WHR are very small. Men, as a group, have a more dangerous fat distribution pattern than women, but men as a group will show a more beneficial pattern of change in WHR with weight control than women.

Reduced HDL2 cholesterol subspecies and elevated postheparin hepatic lipase activity in older men with abdominal obesity and asymptomatic myocardial ischemia.

Silent myocardial ischemia (SI), an asymptomatic manifestation of coronary artery disease (CAD), was identified in 10% of apparently healthy nonsmoking, nondiabetic older (60 +/- 7 years, mean +/- SD) men with normal plasma cholesterol levels. We hypothesized that in the absence of other major risk factors for CAD, the men with SI would have reduced plasma levels of high density lipoprotein (HDL) and HDL2 subspecies due to an upper-body fat distribution (waist-to-hip ratio [WHR]), hyperinsulinemia, and abnormal postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities. Compared with 47 normal control subjects of similar age, obesity, and maximal aerobic capacity, the 18 men with SI had higher plasma triglyceride (TG) (162 +/- 71 versus 102 +/- 39 mg/dl, p less than 0.001) and lower HDL-C (33 +/- 6 versus 37 +/- 7 mg/dl, p less than 0.02) levels with no difference in low density lipoprotein cholesterol level. The HDL2b and HDL2a subspecies measured by gradient gel electrophoresis were also lower in the men with SI (p less than 0.01). The plasma glucose and insulin responses during an oral glucose tolerance test were the same in both groups. Postheparin plasma HL activity was significantly higher in 12 men with SI than in 41 control subjects (34 +/- 8 versus 27 +/- 10 mumol/ml.hr-1, p less than 0.03) and was correlated with log insulin area (r = 0.36, p less than 0.05) and WHR (r = 0.32, p less than 0.05) in the control subjects but not in the men with SI. In the control group, the percent HDL2b subspecies was correlated inversely with postheparin plasma HL activity (r = -0.46, p less than 0.01, n = 41) as well as WHR (r = -0.49, p less than 0.001, n = 47) and log insulin area (r = -0.37, p less than 0.05, n = 47) but not in the men with SI. Postheparin LPL activity was the same in both groups of men and did not correlate with HDL, WHR, insulin, or plasma TG levels. As the control subjects and men with SI had comparable degrees of abdominal obesity and hyperinsulinemia, these results suggest that the reduced HDL-C levels in men with SI may be related to elevations in HL activity. Thus, abdominal obesity, hyperinsulinemia, elevated TG levels, and low HDL-C and HDL2 subspecies levels may predispose these older men to atherosclerosis.