Quantification of concordance and discordance between apolipoprotein-B and the currently recommended non-HDL-cholesterol goals for cardiovascular risk assessment in patients with diabetes and hypertriglyceridemia

AIMS

In patients with diabetes and hypertriglyceridemia, LDL-cholesterol (LDL-C) provides an inaccurate reflection of LDL particle burden. The relative value of non-HDL-cholesterol (non-HDL-C) and apolipoprotein-B (Apo-B) in estimating cardiovascular risk is controversial. We assessed the discordance between non-HDL-C and Apo-B targets in patients with diabetes with TG 200-499 mg/dl.

METHODS

Data from 1430 determinations of LDL-C, non-HDL-C, and Apo-B in ambulatory patients with diabetes were analyzed. Rates of discordance were calculated, based on the currently recommended LDL-C, non-HDL-C, and Apo-B goals.

RESULTS

In patients with non-HDL-C goal of <130 mg/dl, there was a discordance with Apo-B level goal of <90 mg/dl, in 31% of samples. In patients with non-HDL-C goal of <100 mg/dl, 6% of samples had Apo-B ≥80 and 18% had Apo-B <80 mg/dl. Using the Apo-B goal of <70 mg/dl, these numbers were 37% and 3.5% respectively. There was also a significant gender difference, i.e. under-estimation of risk by suggested non-HDL-C cut-offs, in females, compared to males.

CONCLUSIONS

In patients with diabetes and hypertriglyceridemia, a considerable discordance exists between non-HDL-C and Apo-B. Our data suggest a need for prospective studies to compare the relative merits of non-HDL-C and Apo-B targets in the assessment of cardiovascular risk.

Management of patients with diabetes and "abnormal" blood pressure: selection of antihypertensive agents

OBJECTIVE

To characterize the association of diabetes and hypertension and to discuss management strategies.

METHODS

Published studies are summarized and various hypotheses are reviewed.

RESULTS

Hypertension is a major determinant of the increased cardiovascular, peripheral vascular, and renal complications associated with diabetes. Recent evidence indicates that insulin resistance is one of the multiple key components of the pathophysiologic elements underlying the increased prevalence of hypertension associated with diabetes. In patients with diabetes, management of hypertension is frequently complicated by the coexistence of other macrovascular risk factors, including dyslipidemia, obesity, visceral adiposity, and poor glycemic control. The choice of antihypertensive agents in both type I and type II diabetes must be based on the selective metabolic, hormonal, and hemodynamic advantages and disadvantages of these agents in individual patients.

CONCLUSION

Long-term trials are needed to determine the benefits, if any, of various angiotensin-converting enzyme inhibitors, calcium channel antagonists, and alpha1-adrenergic receptor antagonists in preventing the cardiovascular and the renal complications of diabetes.

Efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia

PURPOSE

Patients with type I and type II diabetes mellitus have an increased risk of coronary heart disease. In many diabetics, hypercholesterolemia is present and further exacerbates this risk. We investigated the efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia.

PATIENTS AND METHODS

In this 24-week, multi-center, double-blind, placebo-controlled study, 94 patients (45 men, 49 women), 18 to 70 years of age, with type I or type II diabetes mellitus and hypercholesterolemia (fasting plasma low-density lipoprotein cholesterol [LDL-C] levels > 150 mg/dL and above the 75th percentile for the US population by age and gender) were randomized to receive pravastatin 20 mg hs or matching placebo. Two patients were randomized to treatment with drug for every 1 randomized to placebo. The dose could be doubled after 10 weeks, and cholestyramine or colestipol could be added after 18 weeks, as needed, to attempt to lower the LDL-C levels to below the 50th percentile for the US population.

RESULTS

Significant reductions in LDL-C (-27.6%), total cholesterol (-22.1%), very-low-density lipoprotein cholesterol (-22.6%), and triglycerides (-12.8%) (P < or = 0.001 versus placebo for all reductions), and significant increases in high-density lipoprotein cholesterol (4.4%) (P < or = 0.05 versus placebo) were noted in the pravastatin treatment group (average dose 29.5 mg) at 16 weeks. The beneficial lipid-lowering effects of pravastatin were maintained throughout the 24 weeks of the study. Pravastatin was well tolerated, and the frequency of side effects was similar in the pravastatin and placebo groups. No clinically significant changes in the control of diabetes, as assessed by fasting blood glucose levels and glycosylated hemoglobin measurements, were seen during this study.

CONCLUSION

The results of this study demonstrate that pravastatin is well tolerated and effective in lowering total cholesterol and LDL-C in patients with type I or type II diabetes mellitus and hypercholesterolemia.

Coronary artery disease is the major determinant of excess mortality in patients with insulin-dependent diabetes mellitus and persistent proteinuria

The goal of this review was to assess the magnitude of coronary artery disease (CAD) mortality and its determinants in insulin-dependent diabetes mellitus (IDDM) patients with persistent proteinuria. By reanalyzing data from two previously published studies of patients with nephropathy, it was found that these patients had extremely high CAD mortality rates in comparison with IDDM patients without proteinuria, but only after the age of 35 yr. In addition, the risk of CAD death was associated with high serum cholesterol levels but was unrelated to systemic blood pressure, smoking habits, and obesity. Further studies of the determinants of CAD in patients with IDDM and proteinuria are urgently needed. Except for efforts to lower serum cholesterol, it is not known whether any other measure can be undertaken to reduce the extremely high mortality due to CAD that afflicts IDDM patients with persistent proteinuria, in particular those patients whose renal failure might have been "successfully" postponed by antihypertensive therapy.

Hyperfibrinogenemia. An important risk factor for vascular complications in diabetes

OBJECTIVE

To evaluate the determinants of elevated fibrinogen levels and the impact of hyperfibrinogenemia on vascular complications in diabetes.

RESEARCH DESIGN AND METHODS

Plasma fibrinogen, glucose, HbA1, and lipids were measured in 116 ambulatory type I and type II diabetic patients with (n = 59) or without (n = 57) clinical evidence of micro- or macrovascular complications. In 56 of these patients, factor VII activity and CRP also were measured. Univariate and multivariate data analyses were conducted.

RESULTS

Overall mean +/- SE fibrinogen levels in patients (339 +/- 7.3 mg/dl) were elevated markedly compared with control subjects (248 +/- 9.1 mg/dl). Fibrinogen levels were elevated disproportionately in patients with type II diabetes (P less than 0.0001), hypertension (P = 0.0001), obesity (P less than 0.0001), and vascular complications (P less than 0.0001). Fibrinogen was correlated significantly with age (P less than 0.001), cholesterol (P = 0.002), CRP (P less than 0.001), and factor VII activity (P = 0.032), but not with plasma glucose, triglycerides, HDL cholesterol, or disease duration. Stepwise multiple regression analyses revealed that type II diabetes and presence of vascular complications were major determinants of fibrinogen. For vascular complications, fibrinogen emerged as one of only three independent predictors, the other two being diabetes duration and hypertension.

Different effects of duration on prevalence of anti-adrenal medullary and pancreatic islet cell antibodies in type I diabetes mellitus

Autoimmunity is a known factor in the pathogenesis of islet cell destruction, but little is known of its role in the pathogenesis of the neuronal complications of diabetes. We carried out a cross-sectional study of 94 subjects with Type I diabetes mellitus (DM) to examine the relationship between duration and presence of complement fixing anti-adrenal medullary antibodies (CF-ADM). CF-ADM were present in 19% of subjects (n = 62) with duration of DM less than or equal to 16 years and 3% of subjects (n = 32) with duration of DM greater than 16 years. All subjects with CF-ADM+ and duration of DM 0-5 years (n = 7) were islet cell antibody positive (ICA+). Among subjects with duration of DM 6-16 years who were CF-ADM+, 4 of 5 subjects were ICA- and 1 of 5 subjects was ICA+. The only CF-ADM+ subject with duration of DM greater than 16 years was ICA-. Absorption of ADM+ and ICA+ sera with upper phase glycolipid extract blocks ICA but not ADM binding to tissue. This study suggests: 1) CF-ADM positivity is associated with ICA positivity in subjects with duration of DM 0-5 years. CF-ADM positivity persists after 5 years duration of DM when islet cell antibodies have disappeared. Therefore, the antigenic target of the adrenal medulla and pancreatic islets may be different. 2) There is an increased prevalence of CF-ADM in subjects with duration of DM 0-16 years (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-fetoprotein associated with islet cell tumors

Elevated serum levels of alpha-fetoprotein (AFP) (100-1,000 ng/ml) were found in three patients with islet cell tumors. Serial levels correlated with progression of disease, suggesting that AFP could be a useful tumor marker substance for islet cell tumors. Survey sera from an expanded pool of 23 patients with islet cell tumors and nine with carcinoid tumors did not identify additional cases, however, suggesting that elevated AFP levels in these classes of Apudomas are uncommon. Nonetheless, the distinction from other AFP-producing tumors such as hepatocellular carcinoma is clinically important and warrants an awareness of the rare association of AFP with these tumors.

Diminished A-cell secretion in the early phase of type I diabetes mellitus

The A-cell function in "true pre-type I diabetes" or in early phase of type I diabetes has not been reported. We studied A-cell reserve in response to intravenous arginine infusion in six individuals characterized by type I diabetes-associated immunologic defects and absent first-phase insulin secretory response to intravenous glucose prior to development of diabetes. The peak glucagon response in these patients was markedly impaired (153 +/- 39 pg/mL, mean +/- SEM) compared to a group of 23 normal, healthy controls (301 +/- 18; P less than 0.01) and a group of 11 healthy, discordant monozygotic twins of type I diabetic patients (250 +/- 25, P less than 0.05). The glucagon concentrations in response to oral glucose were completely suppressed to undetectable levels in three of the patients studied. In view of the well-known observations of insulitis in the prediabetic phase in man and in experimental models of type I diabetes and anti-islet cytoplasmic antibodies directed against all islet cells, our observations suggest an impairment of A-cells during the evolution of type I diabetes.

Acquired defect in interleukin-2 production in patients with type I diabetes mellitus

Deficient production of interleukin-2 has been reported in Type I diabetes, but its cause has not been elucidated. We therefore measured interleukin-2 production in 27 patients with Type I diabetes, 20 patients with Type II diabetes (6 requiring insulin), 5 monozygotic twin pairs discordant for Type I diabetes, and 10 nondiabetic persons with islet-cell antibodies. Interleukin-2 production was decreased in patients with Type I diabetes as compared with controls (35.8 +/- 2.5 vs. 61.6 +/- 4.6 percent, P less than 0.001). Interleukin-2 production did not differ between patients with Type II diabetes and controls, regardless of whether the patients used insulin. Twins with Type I diabetes had decreased interleukin-2 production as compared with normal controls (33.2 +/- 5.4 vs. 61.6 +/- 4.6 percent, P less than 0.001) and with their nondiabetic twins (33.2 +/- 5.4 vs. 54.5 +/- 3.4 percent, P less than 0.005). Interleukin-2 production in nondiabetic twins and in nondiabetic persons with islet-cell antibodies was normal. There was no correlation between glycosylated hemoglobin levels and interleukin-2 production in any diabetic group. We conclude that patients with Type I diabetes have an acquired defect in interleukin-2 production, whereas patients with Type II diabetes do not, and that this defect is not correlated with an ongoing autoimmune process, with hyperglycemia, or with insulin administration or oral hypoglycemic therapy. Thus, the defect appears to be related to marked beta-cell destruction, although not to the metabolic consequences thereof or the responsible autoimmune process.

Progressive autoimmune beta cell insufficiency: occurrence in the absence of high-risk HLA alleles DR3, DR4

In a prospective screening program for type I diabetes mellitus, we identified a unique family in which several members (mother and three siblings) expressed an unusual set of HLA-DR alleles (DR2+, DR3/4-) and were in different phases of immunologically mediated islet beta cell dysfunction. Immunologic and/or clinical manifestations of type I diabetes were absent in all siblings not sharing both HLA haplotypes in common with the proband. This article illustrates: the clinical utility of prospective family screening for predictive markers, such as islet cell antibodies, progressive autoimmune beta cell destruction can occur in the absence of the "high-risk" alleles HLA-DR3 and DR4, and HLA identity with the proband, rather than specific HLA alleles, i.e., presence of DR3, DR4 and absence of DR2, is an essential factor.

First-degree relatives of patients with type I diabetes mellitus. Islet-cell antibodies and abnormal insulin secretion

In a prospective study to evaluate the prevalence and predictive potential of circulating islet-cell antibodies, we have screened 1723 "normal" first-degree relatives (parents, siblings, and offspring) of patients with insulin-dependent diabetes mellitus. The prevalence of islet-cell antibodies on initial screening was 0.9 per cent (16 of 1723). Over a maximal follow-up period of two years, insulin-dependent diabetes mellitus developed in 2 of 16 relatives with islet-cell antibodies and in 1 of 1707 without antibodies. In addition, 6 of 12 nondiabetic relatives with islet-cell antibodies had abnormally low insulin responses--below the third percentile in 6 and below the first percentile in 4--on their initial intravenous glucose challenge. Thus, prospective islet-cell antibody screening of high-risk first-degree relatives, in combination with intravenous glucose-tolerance testing, is capable of identifying immunologically abnormal persons with profoundly diminished beta-cell function, who are presumably at increased risk of insulin-dependent diabetes mellitus.

Alterations in plasma lipids in the presence of mild glucose intolerance in the offspring of two type II diabetic parents

Plasma lipids and oral glucose tolerance were determined in 67 normal control subjects (age range 19-67 yr) and 150 individuals (17-69 yr) who were offspring of two type II diabetic parents. Age- and weight-adjusted analyses of covariance were performed for lipids and for glucose and insulin responses. For both men and women, the mean concentrations of total, low-density-, and high-density-lipoprotein-cholesterol and of triglycerides in the offspring with normal glucose tolerance (N = 109) were similar to respective controls. For offspring with abnormal glucose tolerance (N = 41), the mean levels of total cholesterol, LDL-cholesterol, and triglycerides were significantly elevated (P = 0.02 or less) in women but not in men. The mean HDL-cholesterol levels were 20% lower and LDL/HDL-cholesterol ratios 60% greater in women with abnormal glucose tolerance, whereas no significant differences existed for any of the lipid fractions in men, compared with respective controls. Both men and women with abnormal glucose tolerance had a comparable magnitude of hyperglycemia as well as hyperinsulinemia. These observations indicate that significant alterations in plasma lipids exist in individuals with mild, asymptomatic glucose intolerance and there are important sex differences in lipid metabolism in the early stage of diabetes, despite comparable degrees of glucose intolerance and insulin responses.

Pre-type I diabetes. Linear loss of beta cell response to intravenous glucose

Twenty-one intravenous (i.v.) glucose tolerance tests were performed on nine subjects before the onset of overt type I diabetes mellitus. Islet cell antibodies (6 of 9 subjects) and elevated levels of Ia-positive T-lymphocytes (3 of 3 subjects studied) were detected during the prediabetic period. Elevations of fasting blood glucose and peak glucose during oral glucose tolerance tests were not observed until the year before onset of clinically overt diabetes. During the prediabetic period, there was a progressive loss of early-phase insulin release to i.v. glucose (rate of decline, 20-40 microU/ml insulin release/yr; correlation coefficient, 0.9).

Pre-type 1 (insulin-dependent) diabetes: common endocrinological course despite immunological and immunogenetic heterogeneity

In an ongoing prospective study 32 individuals have been evaluated for insulin secretory dynamics, islet cell antibodies and HLA antigens, during the preclinical phase of Type 1 diabetes mellitus. Twenty-four out of the 32 subjects were islet cell antibody-positive. To date, 14 subjects (10 islet cell antibody-positive, four islet cell antibody-negative) have progressed to develop overt diabetes. Several patterns of HLA-DR expression were noted (DR3/DR4, DR3/DR3, DR3/x, DR3/DR1, DR4/x, DR4/DR7, DR5/DR7, DR1/DR7 and DR1/DR2). Irrespective of differences in islet cell antibody status or HLA-DR alleles, pre-diabetic individuals exhibited a similar slow course of progressive beta-cell dysfunction.

Differential sensitivity to beta-cell secretagogues in "early," type I diabetes mellitus

The insulin secretory response to various beta-cell secretagogues was studied in four children (ages 11, 11, 12, and 10 yr) in "early" stages or remission of type I diabetes mellitus. One child was an anti-islet antibody positive monozygotic twin of a type I diabetic subject, two children had impaired glucose tolerance and elevated levels of Ia-positive T-cells, and the fourth was in remission (off insulin) of type I diabetes 6 mo after immunotherapy. The peak first-phase (0-10 min) insulin increment after intravenous (i.v.) glucose was negligible in each patient, whereas the peak responses to i.v. glucagon, tolbutamide, arginine, and oral glucose ranged between 10% and 43% of median responses in normal control subjects. The rank order of response to a variety of secretagogues was remarkably similar in all four subjects: i.v. arginine greater than i.v. glucagon greater than oral glucose greater than i.v. tolbutamide greater than i.v. glucose. These studies indicate that a "functional" beta-cell defect, namely a complete loss of response to i.v. glucose and a partial loss to other secretagogues, exists in type I diabetic patients before complete beta-cell destruction. This alteration in beta-cell responsiveness probably underlies our prior observation of slowly progressive loss of i.v.-glucose-induced insulin release in islet cell antibody-positive siblings to type I diabetic subjects.

Pancreatic somatostatinoma: abundance of somatostatin-28(1-12)-like immunoreactivity in tumor and plasma

In the present study we characterized and compared the relative amounts of the different molecular forms of somatostatin-14 like immunoreactivity (S-14 LI) and of somatostatin-28(1-12) like immunoreactivity (S-28(1-12) LI) in extracts of tumor and peripheral plasma of a patient with a pancreatic somatostatinoma. Tissue and plasma were chromatographed on Sephadex G-50 columns equilibrated with 6 M urea. Immunoreactivity in the eluting fractions was assayed with two separate, region specific RIAs using antibodies R149 (S-14 LI) and S309 (S-28(1-12)LI). RIA R149 recognizes the 6-8 and 14 regions of the S-14 sequence and detects S-14, S-28, and prosomatostatin, an approximately 14,000 mol wt precursor for the two peptides. RIA S309 recognizes the 2-11 segment of S-28 and reacts with S-28, S-28(1-12), and higher mol wt S-28(1-12) LI but not S-14. Total tumor S-14 LI was 190 pmol/mg protein and consisted of three peaks of immunoreactivity of apparent 14,000 mol wt (14K S-14 LI), 3,200 mol wt (3.2K corresponding to S-28) and 1,600 mol wt (1.6K corresponding to S-14). The three peaks comprised, respectively, 7%, 57%, and 36% of total S-14 LI. Total tumor S-28(1-12) LI was 594 pmol/mg protein and eluted as four major peaks of immunoreactivity as follows: peak I (mol wt 15,000, 10% of total S-28(1-12) LI); peak II (mol wt 8,000, 20% of S-28(1-12) LI), peak III (corresponding to S-28, 19% of S-28(1-12) LI); peak IV (corresponding to S-28(1-12), approximately 50% of total S-28(1-12) LI). Total plasma concentration of S-14 LI was 714 pM, being made up of the three peaks found in tumor but in the following relative amounts (14K S-14 LI, 22%; 3.2K, 29%; 1.6 K, 49%). Plasma S-28(1-12) LI was 4 times higher (2879 pM) than S-14 LI and contained immunoreactivity corresponding to each of the four peaks found in the tumor.

CONCLUSIONS

1) The tumor and plasma concentrations of S-28(1-12) LI were greater than that of S-14 LI. 2) Both tumor and plasma S-14 LI and S-28 LI were heterogeneous and comprised species corresponding not only to S-14 but also S-28, S-28(1-12), prosomatostatin, and other higher mol wt forms of S-28.(ABSTRACT TRUNCATED AT 400 WORDS)

Type I diabetes mellitus in monozygotic twins: chronic progressive beta cell dysfunction

In a prospective 21-year study, islet cell antibodies and beta cell function were serially assessed in 24 monozygotic twins initially discordant for type I diabetes mellitus. Eighteen of 21 twins typed had HLA-DR3 or HLA-DR4 antigens. During the follow-up, 4 twins developed type I diabetes mellitus, and in 3 of these 4 twins islet cell antibodies preceded the diagnosis of clinical diabetes mellitus by greater than 8, 5 and 7 years respectively. During the "prediabetic phase," the presence of islet cell antibodies was temporally associated with a progressive decline in first phase insulin response to intravenous glucose. Elevations in fasting blood glucose and abnormalities on oral glucose tolerance tests appeared only later during the course of the disease. Of the remaining 20 twins who continue to be discordant for type I diabetes mellitus, two have had islet cell antibodies for greater than 1.5 and 1 year respectively. One of these islet cell antibody-positive non-diabetic twins was restudied; despite a fasting blood glucose level of 64 mg/dL, she had a total absence of first phase insulin response to intravenous glucose. There was no evidence of transient islet cell antibody positivity in any of the twins studied. Type I diabetes mellitus in monozygotic twins has a prolonged prediabetic phase of progressive beta cell dysfunction with associated immunologic abnormalities.

The effect of strict control with the artificial beta-cell on plasma lipid levels in insulin-dependent diabetes

The artificial beta-cell can establish normoglycemia within 2 h in an indifferently controlled diabetic patient. In the present study, the temporal relationship between the achievement of normoglycemia and its effect on plasma lipid concentrations has been examined in 12 insulin-dependent diabetic patients regulated by the artificial beta-cell for 7 days. The fasting values (mean +/- SEM) of blood glucose (BG), triglycerides (TG), total cholesterol (T-chol), HDL-cholesterol (HDL), and the calculated LDL/HDL ratio (obtained while participants were on single or split insulin regimens) were 385 +/- 42 mg/dl, 148 +/- 24 mg/dl, 219 +/- 22 mg/dl, 39 +/- 3.6 mg/dl, and 3.8 +/- 1.04, respectively. Within 12 h of establishing normoglycemia TG levels fell to 87 +/- 10 mg/dl (P less than 0.001), T-chol to 196 +/- 15 mg/dl (P less than 0.005), and HDL to 37 +/- 3 mg/dl (P = NS). The LDL/HDL ratio remained unchanged. After 7 days on the artificial beta-cell, the corresponding values were: 73 +/- 5 mg/dl (P less than 0.001), 169 +/- 9 mg/dl (P less than 0.001), 41 +/- 2.6 mg/dl (P = NS), and 2.6 +/- 0.56 (P less than 0.05). Twenty-four hours after discontinuation of artificial beta-cell therapy, the TG and T-chol concentrations reverted to baseline. These findings underscore the rapidity and effectiveness with which strict control can improve plasma lipid profiles.

Muscle capillary basement membrane width and its relationship to diabetes mellitus in monozygotic twins

Quadriceps (Q) and gastrocnemius (G) muscle capillary basement membrane width (CBMW) were measured in 18 pairs of monozygotic (MZ) twins. Thirteen of these twin pairs were discordant for insulin-dependent diabetes (IDD) and five pairs were concordant for either IDD (two pairs) or for non-insulin-dependent diabetes (NIDD). In 12 of the 13 nondiabetic (ND) twin mates of IDD, 50 oral glucose tolerance tests performed in the years before or after determination of CBMW revealed mean blood glucose levels in the 36-52 percentile range, compared with normal controls. The mean (+/-SD) age at the onset of IDD in discordant twins was 18.7 +/- 10.1 (range 8-37) yr and the mean duration of discordance at the time of biopsy was 13.6 +/- 8.3 (range 3-32) yr. CBMW data were compared within each twin (Q versus G) and between twin mates and age- and sex-matched controls. Overall, CBMW of IDD twins was greater than that of their ND twin mates. Differences between IDD and ND twins, however, were much more marked in gastrocnemius (1859 +/- 643 versus 1222 +/- 307 A, P less than 0.0003) than in quadriceps (1291 +/- 319 versus 1112 +/- 302 A; P less than 0.04). CBMW in gastrocnemius was significantly thicker than that in the quadriceps of IDD twins (t = 4.55, P less than 0.0008) but not in their ND twin mates (t = 1.15, P less than 0.27). CMBW was significantly thicker in IDD than in their ND twin mates (in quadriceps and/or gastrocnemius) in 10 of the 12 twin pairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of lipid status in diabetic boys: the 1971 and 1979 Joslin Camp lipid levels

Since 1972, young type I diabetic patients seen by Joslin Clinic physicians have been advised to use a low cholesterol diet with a high proportion of polyunsaturated fat. Mean fasting cholesterol and triglyceride levels at admission to the Joslin Boys Camp for the years 1971 (N = 129) and 1979 (N = 79) were compared. In 1979, the mean cholesterol level was lower by 44 mg/dl (P less than 0.001) and the mean triglyceride by 21 mg/dl (P less than 0.001) compared with 1971. The incidence of hyperlipoproteinemia decreased from 21.6% to 7.6% with a complete disappearance of types IV and V during the same period. A decrease in the development of arteriosclerotic cardiovascular diseases in type I diabetic patients might be anticipated from this diet modification.

The role of gastrointestinal and neuronal peptides in the pathophysiology of diabetes mellitus

The pancreatic islet hormone secretion is modulated by one or more gastrointestinal peptides ("gut-factor") secreted in response to various types of ingested nutrients. Among a number of postulated candidates for the putative "gut-factor", the gastric inhibitory polypeptide (GIP) has recently emerged as a most likely enteric signal of physiologic import, although its precise role in the pathophysiology of diabetes mellitus remains incompletely understood. During the past decade, an avalanche of knowledge has accumulated regarding a number of peptide agents common to the gastro-enteric-pancreatic system and the nervous system. Preliminary evidence indicates a potential role of several of these peptides in the pathophysiology of diabetes. For instance, cholecystokinin and human pancreatic polypeptide (hPP) may be importantly involved in the regulation of appetite and satiety control and the development of obesity whereas somatostatin, "endorphins", and neurotensin may directly or indirectly modulate islet hormone secretion. Finally the significance of the recently demonstrated presence of insulin and glucagon or glicentin-like peptides in the brain requires close scrutiny.

Insulin resistance and monoclonal gammopathy

Two maturity-onset diabetic patients developed severe insulin resistance during the course of monoclonal gammopathies. One patient had Waldenström macroglobulinemia and the other had multiple myeloma with IgA gammopathy. The maximum insulin binding capacity (MIBC) was 121 U/liter and 54.7 U/liter, respectively, during insulin resistance. The clinical courses of insulin resistance paralleled the activity of the monoclonal gammopathies (MG) with the insulin resistance disappearing after the monoclonal gammopathies were controlled. Six other diabetic patients with concurrent insulin resistance and monoclonal gammopathies are reviewed.

Hypertension: the major risk factor in juvenile-onset insulin-dependent diabetics

The prevalence of hypertension in various age groups of diabetics and its role as a risk factor in juvenileonset insulin-dependent diabetics followed for 40 yr after diagnosis was evaluated. The results show clearly that hypertension is more prevalent in diabetics of any age after age 24 yr than in the general population.

In this type of diabetes, although death due to renal disease occurs earlier than that due to coronary heart disease, both causes of death are significantly related to hypertension. Those patients with an onset of diabetes 13 yr of age or younger can expect to live longer following the diagnosis of diabetes mellitus than those with an onset after 13 yr of age, perhaps because hypertension appears at about the same age in both groups. Case/control analysis of the data shows that survivors have significantly less hypertension than those dying of renal or cardiac disease. Furthermore, the close temporal relationship between the onset of hypertension and the onset of proteinuria in patients with either renal or coronary deaths suggests that the hypertension in these patients is renal in origin.

Two other risk factors, smoking and serum lipids, were evaluated in this population. From the data thus far accumulated, neither smoking nor lipids appear to influence mortality significantly. We conclude that hypertension is the major additive risk factor for mortality in juvenile-onset insulin-dependent diabetics.

Metabolic effects of glucose, mannose, galactose, and fructose in man

The effects of various hexoses upon immunoreactive insulin (IRI) secretion, glucose disposal, and gastric inhibitory polypeptide (GIP) release have been compared in 10 normal nonobese men. Rapid iv infusion (0.5 g/kg in 3 min) of D-mannose resulted in significant ITI release, the peak levels approaching those after D-glucose infusion. D-Galactose, however, was ineffective. The 60-min urine excretions of mannose, galactose, and glucose were 35 +/- 7%, 16 +/- 4%, and 5.5 +/- 0.7% (mean +/- SEM) of the administered dose, respectively. All subjects also received 50 g oral glucose, mannose, galactose, and fructose on different days, each followed by an iv glucose infusion 30 min later. The ingestion of glucose or galactose resulted in a similar increment of GIP (P less than 0.01), followed by a similar increment in the IRI response to iv glucose. Furthermore, the glucose disposal rate increased 2.5-fold compared to that after iv glucose alone (P less than 0.001). However, oral msnnose or oral fructose caused no significant GIP release, yet the IRI response to a subsequent iv glucose load was moderately augmented after oral mannose or oral fructose when compared to iv glucose alone. In addition, there was a similar enhancement of glucose disposal of the iv glucose load after both oral mannose and oral fructose (P less than 0.01). From these studies we conclude that 1) galactose does not elicit IRI secretion per se, yet, like glucose, potentiates GIP and IRI secretion; 2) mannose, despite weak transport across gut or kidney, evokes significant betacytotropic effects; and 3) mannose- and fructose-induced enhancement of glucose disposal might be mediated by a factor(s) other than GIP.

Factors governing insulin and glucagon responses during normal meals

An experimental model is described which can be used to study substrate and hormone responses to normal meals administered in very near normal circumstances. After 500, 300 and 125 calorie meals, the relative proportion of fat or protein content did not influence the plasma glucose except for minor differences between the high protein-high fat meals. The insulin response to such meals was correlated positively with the increment in glucose but reduction of protein content below 8 g caused a signficant reduction in the increment in plasma insulin per unit increase in plasma glucose. Alterations in protein content above 8 g made no difference. Fat content of the meal did not significantly alter the insulin response. No evidence was obtained for a major component of insulin release attributable to either bulk or preabsorption phenomena such as sight or smell. It is concluded that a significant accentuation of the insulin response to meals is dependent on a minimum amount of protein and that this is probably mediated by one of the gastro-intestinal hormones. Glucagon release is dependent on protein and carbohydrate content of the meal and is independent of the fat content. There may also be an early stimulation of glucagon release, regardless of content, which may also be hormonally mediated.

Transient suppression of growth hormone secretion after chronic ethanol intake

Fifty-two percent of patients with chronic heavy intake of ethanol had an abnormally low growth hormone (GH) response to propranolo-glucagon. The effect of ethanol is transient, since the GH response was normal in patients studied 2 wk or more after withdrawal of ethanol. The low GH response was not due to a difference in the levels of glucose or insulin. Ethanol probably suppresses the GH response by acting on the hypothalamus or pituitary gland. Along with previous data suggesting transient ACTH deficiency in chronic alcoholic patients, our findings suggest that these patients may have multiple hypothalamic-pituitary deficiencies.

Reproducibility and comparative analysis of repeated intravenous and oral glucose tolerance tests

We have developed a methodology for measuring the reproducibility of the oral glucose tolerance test (OGTT) and the intravenous glucose tolerance test (IVGTT) in normal subjects and in offspring of conjugal diabetic parents. Both groups of subjects revealed more striking correlations of several parameters of blood glucose and insulin secretion between two IVGTTs than between two OGTTs. Employing arbitrary criteria, we calculated a "reproducibility index" as a quantitative measure of blood glucose variability in each subject. No significant difference was found in the reproducibility of OGTT versus IVGTT, nor in normals versus the offspring. Only about 50 per cent of the tests in normals and in the offspring could be considered to be "reproducible." The offspring revealed greater correlations of several parameters, particularly insulin secretion, between the two IVGTTs and between the two OGTTs as compared with the normal group. However, the blood glucose variations tended to be considerably greater in the offspring from one to the other test.

Portacaval diversion for severe hypercholesterolemia. Report of a case with measurements of glucose tolerance, insulin, and glucagon levels

An end-to-side portacaval shunt was performed in a patient with severe coronary arteriosclerosis and type IIa hypercholesterolemia. By one year postoperatively there was a decrease of serum cholesterol concentration of more than 40%. No adverse side effects were noted. Intravenous and oral glucose tolerance tests were performed and were within normal range preoperatively and postoperatively. However, preoperatively, during the oral test, the serum insulin levels exceeded the normal range. In addition, glucagon levels revealed less tendency to suppression during the preoperative oral tests. Psychological testing revealed no abnormalitites, and serum ammonia levels were only slightly elevated.

Monozygotic triplets with discordance for diabetes mellitus and diabetic microangiopathy

A set of monozygotic triplets (PE.K., P.K., S.K.) has been studied. There is no diabetes in first-degree relatives. PE.K. developed insulin-requiring (60 U. NPH) diabetes at the age of 13 years. Over a period of 11 years since that time, numerous studies of insulin and growth-hormone secretion were performed on P.K. and S.K., including multiple oral glucose tolerance tests (OGTTs), cortisone-primed oral glucose tolerance tests (C-OGTTs), intravenous glucose tolerance tests (IVGTTs), and intravenous tolbutamide tests (IVTTs). The results of each test were compared with age- and sex-matched control subjects. P. K. developed insulin-requiring (56 U. NPH) diabetes after remaining discordant for eight years. Glucose, insilin, and growth-hormone responses during all tests were normal except during the IVGTT performed four months prior to the onset of diabetes. This last IVGTT revealed a glucose disappearance rate of 0.98 per cent per minute, and the slope of the regression line of serum-insulin response (IRI) on blood glucose (BG) was markedly decreased to 0.005 micronU./ml. IRI/mg./dl. BG (controls 0.340 +/- 0.04; mean +/- S.E.M.). The insulin responses in P.K. and S.K. were similar during all OGTTs, C-OGTTs, and IVTTs. S.K. has continued to maintain normal glucose tolerance and normal insulin and growth-hormone responses during all tests. The histocompability antigen studies have revealed HLA-A2, AW24, BW15, and BW40 phenotype in these monozygotic triplets. Muscle capillary basement membranes of the nondiabetic triplet were normal, whereas both diabetic triplets manifested evidence of capillary basement membrane thickening. The clinical and biochemical profiles in these triplets and the capillary basement membrane data lend strong credence to the role of "nongenetic" determinants in the development of "genetic" diabetes as well as diabetic microangiopathy in juvenile-onset-type diabetes.

"Somatostatinoma": a somatostatin-containing tumor of the endocrine pancreas

We studied the pancreatic and enteric hormone profile of a 46-year-old woman who had hyperglycemia and a pancreatic tumor. Before operation, there was no evidence of overproduction of glucagon or insulin. The tumor's ultrastructure had a distinctive endocrine morphology, resembling D cells. Prompted by the recent demonstration of somatostatin in D cells of pancreatic islets, we analyzed the tumor and found a large quantity of immunoreactive somatostatin (301 ng per milligram of tissue). Insulin, glucagon, gastrin, vasoactive intestinal polypeptide and human pancreatic polypeptide were present in only trace quantities. The tumor cells were cultured in monolayers, which remained viable up to 51 days and released somatostatin into the culture medium. In seven insulinomas and two glucagonomas, we found the somatostatin content either much lower (less than 0.6 ng per milligram of tissue) or undetectable. After complete resection of the tumor, our patient became euglycemic and has remained so for the past 20 months.

Genetic, acquired, and related factors in the etiology of diabetes mellitus

Diabetes mellitus is not a single disease entity, but a heterogenous group of disorders with a striking diversity of etiopathogenetic mechanisms as well as clinical manifestations. Lack of a known genetic marker for the disease(s) and variable influences of environmental factors on the expression of a putative diabetic genome have resulted in considerable debate over its etiology. Over the past few years, systematic epidemiologic studies, along with knowledge gained from a close association of certain human-leukocyte-antigens with the diabetic diathesis and possible role of host-immune factors, and gene-virus interaction have led to considerable advancement in the understanding of the disease-complex. Pending the availability of definite genetic marker(s), we propose a new, tentative classification based on the etiologic mechanisms. We also suggest that the term "prediabetes" be abandoned as a prospective entity, since as presently employed, this connotation carries a risk probability no different than the terms like prehypertension or precoronary thrombosis.

Studies on streptozotocin diabetes

Both alloxan and streptozotocin produce beta-cell necrosis in the rat. Previous studies have shown protection against alloxan toxicity by D-glucose, D-mannose, and the nonmetabolized analogue 3-0-methyl-D-glucose and removal of this protective effect by D-mannoheptulose. The effect of several agents (i.v. infusion) against the beta-cell toxic effect of streptozotocin (60 mg./kg. i.v. in 24-hour-fasted 200-gm. male rats) was studied. Protection was determined by plasma glucose concentrations 24 and 48 hours later and, in certain experiments, by histologic examination of the islets. D-glucose and D-mannose provided no protection. Similarly, D-galactose, D-fructose, alpha-methyl-D-glucoside, D-L-glyceraldehyde, D-xylose, and D-glucosamine had no effect. However, 3-0-methyl-D-glucose administered immediately before streptozotocin resulted in progressive inhibition of beta-cell toxicity with complete protection at 0.83 mMoles per rat. The protective effect of 3-0-methyl-D-glucose was not altered by mannoheptulose. 2-Deoxy-D-glucose, which has no effect against alloxan, provided nearly complete protection against streptozotocin at 2.2 mMoles per rat. The effects of 3-0-methyl-D-glucose and 2-deoxy-D-glucose were additive and were not altered by glucose. Furthermore, the 3-0-methyl-D-glucose as well as 2-deoxy-D-glucose protective effects were still present, albeit attenuated, when these agents were given following the administration of streptozotocin. This is in contrast to alloxan, against which 3-0-methyl-D-glucose provides protection only when given before alloxan. 3-0-Methyl-D-glucose is the only carbohydrate protective against both streptozotocin and alloxan in the rat. However, several silent differences seem to exist between the mechanisms of beta-cytotoxic effects of these two diabetogenic compounds.

Hormone-fuel concentrations in anephric subjects. Effect of hemodialysis (with special reference to amino acids)

Arterial blood concentrations of insulin, glucagon, and various substrates were determined in six anephric subjects in the postabsorptive state and immediately after hemodialysis. Plasma glucose and serum insulin concentrations were normal, and declined during dialysis. Plasma glucagon was elevated and remained unchanged. There was moderate hypertriglyceridemia before dialysis, but this decreased significantly after administration of heparin just before the start of dialysis, and at the end of dialysis was lowered further into the normal range. Comparison of postabsorptive whole blood concentrations of amino acids with those in normal, healthy adults revealed striking differences. Glutamine, proline, citrulline, glycine and both 1- and 3-methyl-histidines were increased, while serine, glutamate, tyrosine, lysine, and branched-chain amino acids were decreased. The glycine/serine ratio was elevated to 300% and tyrosine/phenylalanine ratio was lowered to 60% of normal. To investigate the potential role of blood cells in amino acid transport, the distribution of individual amino acids in plasma and blood cell compartments was studied. Despite a markedly diminished blood cell mass (mean hematocrit, 20.6 +/- 1.4%), there was no significant decrease in the fraction of most amino acids present in the cell compartment, and this was explained by increases of several amino acids in cellular water. None were decreased. Furthermore, during dialysis, whole blood and plasma amino acids declined by approximately 30% and 40%, respectively, whereas no significant change was observed in the cell compartment. Alanine was the only amino acid whose concentration declined in the cells as well as in plasma. The results indicate (a) significant alterations in the concentrations of hormones and substrates in patients on chronic, intermittent hemodialysis; (b) removal of amino acids during hemodialysis, predominantly from the plasma compartment, with no significant change in cell content; and (c) a redistribution of amino acids in plasma and blood cell compartments with increased gradients of most of the amino acids per unit cell water, by mechanism(s) as yet undetermined.

Muscle nitrogen metabolism in chronic hepatic insufficiency

Whole blood arterio-venous (A-V) differences for ammonia (NH3) and amino acids were determined across the forearm in 14 patients with decompensated alcoholic cirrhosis and hyperammonemia. NH3 was extracted by the forearm in all patients; however, the fractional extraction of NH3 was significantly less in five individuals with gross muscle wasting (13.3% versus 25.3%). There was neither a significant uptake nor release of NH3 in normal control subjects. The arterial concentrations of 12 out of 20 amino acids were strikingly diminished in the patient group. In contrast to normal subjects, in whom the release of alanine exceeds that of glutamine, the A-V difference for glutamine in the patients was threefold greater than that for alanine. The A-V differences for all other amino acids were not significantly different from zero. The results suggest that (1) muscle plays an important role in disposing of NH3 in patients with hepatic insufficiency and (2) a major fraction of NH3 taken up by muscle is released as glutamine.

Alanine-induced amino acid interrelationships

Six normal subjects received 10 g of alanine both orally and as a 60-min intravenous infusion. In both studies blood samples for hormones and substrates were obtained every thirty minutes for 2 1/2 hour. Significant increases in whole blood levels of threonine, serine, glutamine, proline, glycine, and alpha-amino-n-butyric acid were found, which were mainly due to increases of these amino acids in the plasma compartment. In contrast, whole blood levels of leucine, valine, and isoleucine declined, mainly due to increases in the cell compartment. Plasma glucagon levels increased in both studies while insulin levels rose significantly only during the oral study. Plasma free fatty acids and blood glycerol levels declined while lactate and pyruvate increased. Glucose concentration did not change during both tests. These data suggest that the administration of large quantities of alanine is capable of inducing significant alterations in levels of other amino acids and substrates as well as changing hormone levels.