Effects of obesity and body fat distribution on lipids and lipoproteins in nondiabetic American Indians: The Strong Heart Study

OBJECTIVES

To examine the relationship between obesity and lipoprotein profiles and compare the effects of total obesity and central adiposity on lipids/lipoproteins in American Indians.

RESEARCH METHODS AND PROCEDURES

Participants were 773 nondiabetic American Indian women and 739 men aged 45 to 74 years participating in the Strong Heart Study. Total obesity was estimated using body mass index (BMI). Central obesity was measured as waist circumference. Lipoprotein measures included triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein AI (apoAI), and apolipoprotein B (apoB). Partial and canonical correlation analyses were used to examine the associations between obesity and lipids/ lipoproteins.

RESULTS

Women were more obese than men in Arizona (median BMI 32.1 vs. 29.2 kg/m2) and South Dakota and North Dakota (28.3 vs. 28.0 kg/m2), but there was no sex difference in waist circumference. Men had higher apoB and lower apoAI levels than did women. In women, when adjusted for center, gender, and age, BMI was significantly related to HDL cholesterol (r = -0.24, p < 0.001). There was a significant but weak relation with apoAI (r = -0.14, p < 0.001). Waist circumference was positively related to triglycerides (r = 0.14, p < 0.001) and negatively related to HDL cholesterol (r = -0.23, p < 0.001) and apoAI (r = -0.13, p < 0.001). In men, BMI was positively correlated with triglycerides (r = 0.30, p < 0.001) and negatively correlated with HDL cholesterol (r = -0.35, p < 0.001) and apoAI (r = -0.23, p < 0.001). Triglycerides increased with waist circumference (r = 0.30, p < 0.001) and HDL cholesterol decreased with waist circumference (r = -0.36, p < 0.001). In both women and men there was an inverted U-shaped relationship between obesity and waist with LDL cholesterol and apoB. In canonical correlation analysis, waist circumference received a greater weight (0.86) than did BMI (0.17) in women. However, the canonical weights were similar for waist (0.46) and BMI (0.56) in men. Only HDL cholesterol (-1.02) carried greater weight in women, whereas in men, triglycerides (0.50), and HDL cholesterol (-0.64) carried a large amount of weight. All the correlation coefficients between BMI, waist circumference, and the first canonical variable of lipids/lipoproteins or between the individual lipid/lipoprotein variables and the first canonical variable of obesity were smaller in women than in men. Triglycerides and HDL cholesterol showed clinically meaningful changes with BMI and waist circumference in men. All lipid/lipoprotein changes in women in relation to BMI and waist circumference were minimal.

DISCUSSION

The main lipoprotein abnormality related to obesity in American Indians was decreased HDL cholesterol, especially in men. Central adiposity was more associated with abnormal lipid/lipoprotein profiles than general obesity in women; both were equally important in men.

Relation of generalized and central obesity to cardiovascular risk factors and prevalent coronary heart disease in a sample of American Indians: the Strong Heart Study

OBJECTIVE

To examine the hypothesis linking measures of obesity including body mass index (BMI), waist circumference (waist) and percentage body fat to coronary heart disease (CHD) prevalence and its risk factors in American Indians.

DESIGN

The Strong Heart Study assesses the prevalence of CHD and its risk factors in American Indians in Arizona, Oklahoma and South/North Dakota. Participants underwent a physical examination and an electrocardiogram; anthropometric and blood pressure measurements were taken, as were measurements of glucose, lipoproteins, fibrinogen, insulin, hemoglobin A1c and urinary albumin.

PARTICIPANTS

Data were available for 4549 men and women between 45 and 74 y of age.

MEASUREMENTS

Obesity, measured using body mass index, waist circumference and percentage body fat, was correlated with prevalent CHD and its risk factors.

RESULTS

More than 75% of participants were overweight (BMI>25 kg/m2). Measures of obesity were greater in women than in men, in younger than in older participants, and in participants with diabetes than in nondiabetic participants. CHD risk factors were associated with measures of obesity but, except for insulin concentration, changes in metabolic variables with increasing obesity were small. Associations were not stronger with waist than with BMI. The prevalence of CHD in those whose BMI and/or waist measurements lay in the lowest and highest quintiles, by gender and diabetic status, was similar.

CONCLUSIONS

Although CHD risk factors are associated with obesity in American Indians, distribution of obesity (ie waist) is no more closely related to risk factors than is generalized obesity (ie BMI), and changes in CHD risk factors with obesity were small. Thus, the relations among obesity, body fat distribution and CHD risk may differ in this population.

LDL cholesterol as a strong predictor of coronary heart disease in diabetic individuals with insulin resistance and low LDL: The Strong Heart Study

Diabetes has been shown to increase the risk of coronary heart disease in all populations studied. However, there is a lack of information on the relative importance of diabetes-associated risk factors for cardiovascular disease (CVD), especially the role of lipid levels, because low density lipoprotein (LDL) cholesterol often is not elevated in diabetic individuals. The objective of this analysis was to evaluate CVD risk factors in a large cohort of diabetic individuals and to compare the importance of dyslipidemia (ie, elevated triglycerides and low levels of high density lipoprotein [HDL] cholesterol) and LDL cholesterol in determining CVD risk in diabetic individuals. The Strong Heart Study assesses coronary heart disease and its risk factors in American Indians in Arizona, Oklahoma, and South/North Dakota. The baseline clinical examinations (July 1989 to January 1992) consisted of a personal interview, physical examination, and drawing of blood samples for 4549 study participants (2034 with diabetes), 45 to 74 years of age. Follow-up averaged 4.8 years. Fatal and nonfatal CVD events were confirmed by standardized record review. Participants with diabetes, compared with those with normal glucose tolerance, had lower LDL cholesterol levels but significantly elevated triglyceride levels, lower HDL cholesterol levels, and smaller LDL particle size. Significant independent predictors of CVD in those with diabetes included age, albuminuria, LDL cholesterol, HDL cholesterol (inverse), fibrinogen, and percent body fat (inverse). A 10-mg/dL increase in LDL cholesterol was associated with a 12% increase in CVD risk. Thus, even at concentrations well below the National Cholesterol Education Program target of 130 mg/dL, LDL cholesterol is a strong independent predictor of coronary heart disease in individuals with diabetes, even when components of diabetic dyslipidemia are present. These results support recent recommendations for aggressive control of LDL cholesterol in diabetic individuals, with a target level of <100 mg/dL.

Circulating tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in proliferative diabetic retinopathy: a pilot study

Several haemostatic abnormalities are associated with proliferative diabetic retinopathy. While abnormalities in plasma fibrinolytic activity have been described in diabetic retinopathy, platelets (a rich source of plasminogen activator inhibitor type 1, PAI-1) have received little attention. As a result, little is known about the fibrinolytic potential of circulating whole blood in diabetic retinopathy. The concentrations of tissue-type plasminogen activator (t-PA) and of its fast-acting inhibitor. PAI-1 were measured in plasma from eight patients with type 1 diabetes complicated by proliferative retinopathy, and from eight patients with type 1 diabetes and background or no retinopathy, matched for age, sex and duration of diabetes. The concentration of PAI-1 in platelets was also measured. The ratio of t-PTA to PAI-1 in plasma was significantly higher in patients with proliferative retinopathy than in those without (0.66 vs. 0.37, p < 0.02). The average quantity of PAI-1 per platelet was significantly lower in the group with proliferative retinopathy (0.33 vs. 0.50 ng/10(6) platelets, p < 0.02). These data suggest that among patients with type 1 diabetes, total circulating fibrinolytic potential is higher in those with proliferative retinopathy.

Risk factor clustering in the insulin resistance syndrome. The Strong Heart Study

The objective of this study was to examine how the major components of the insulin resistance syndrome relate to each other and to macrovascular disease in American Indians in the Strong Heart Study. The study cohort (4,228 resident tribal members 45-74 years old) underwent a personal interview and a physical examination between July 1989 and January 1992 at three centers: Arizona, Oklahoma, and North and South Dakota; blood samples were drawn and a 75-g oral glucose tolerance test was performed. Factor analysis was used to assess the clustering and interdependence of groups of insulin resistance syndrome variables. Within both diabetic and nondiabetic groups, three factors emerged. In nondiabetic participants, a cluster of glucose, body mass index, and insulin accounted for 35% (male) and 32% (female) of the total variance in all variables considered, and a cluster of systolic blood pressure and diastolic blood pressure accounted for 25% and 22% in men and women, respectively. Both clusters were positively associated with coronary heart disease but not peripheral vascular disease. In diabetic participants, the combination of systolic and diastolic blood pressures was the most important factor, but the cluster was not associated with coronary heart disease or peripheral vascular disease. A component containing high density lipoprotein cholesterol, triglycerides, and glucose had a positive association with coronary heart disease in diabetic women and with peripheral vascular disease in both sexes. The association of clusters of risk factors and their relations with coronary heart disease provide important clues that may be used in understanding the metabolic disorders associated with insulin resistance and diabetes.

Does chronic smoking influence fibrinolytic potential in type 1 diabetes mellitus?

Tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) were studied in 18 smokers and 18 closely matched non-smokers, all of whom had Type 1 diabetes mellitus (DM). None of the patients had advanced complications of diabetes. The t-PA and PAI-1 antigen levels were measured in plasma before and after venous occlusion, and were normal in Type 1 diabetes regardless of smoking status. Platelet PAI-1 levels were also measured and were found to be normal both in smokers and non-smokers. In smokers with Type 1 DM, plasma PAI-1 was significantly correlated with triglycerides. The normal fibrinolytic potential found in smokers with diabetes contrasts starkly with the significantly elevated plasma PAI-1 reported in smokers without diabetes. In smokers, triglycerides may effect low levels of PAI-1 release into plasma; this process may be significantly augmented in the presence of smoking-induced insulin resistance. The lack of endogenous insulin release in Type 1 diabetes may obviate the characteristic rise in plasma PAI-1 found in smokers who do not have diabetes.

Successful long-term kidney-pancreas transplants in diabetic patients with high C-peptide levels

BACKGROUND

Pancreas transplants are rarely done in type 2 (noninsulin dependent) diabetic patients. Most researchers believe that in type 2 diabetic patients, peripheral insulin resistance plays a central role and also is associated with relative insulin deficiency or an insulin secretory defect. This suggests that in patients receiving transplants, the new beta cells will be overstimulated, leading to beta cell "exhaustion" and graft failure.

METHODS

Early in our experience, simultaneous pancreas-kidney transplant candidates were selected using only clinical criteria for type 1 diabetes, i.e., early onset of diabetes and rapid onset of insulin use. Pretransplant sera were available for C-peptide analysis in 70 of 94 of those patients. Forty-four percent (31/70) were African American (AA).

RESULTS

Thirteen patients (12 AA) with a nonfasting C-peptide level >1.37 ng/ml were identified. In these patients with high C-peptide levels, pancreas and kidney survival rates were 10O%. The results did not differ statistically from the low C-peptide group (< or =1.37 ng/ ml). There were no differences between patient and pancreas-kidney survival rates when the patients were separated into AA and non-AA groups. The follow-up was 1-89 months, with a mean of 45.5 months.

CONCLUSIONS

Long-term pancreas graft function is attainable and beta cell "exhaustion" does not occur in patients with high preoperative C-peptide (>1.37 ng/ ml) levels. AA and non-AA patients have equivalent long-term patient, kidney, and pancreas-kidney graft survival rates.

Molecular cloning and characterization of an invertebrate cellular retinoic acid binding protein

We have cloned a cDNA and gene from the tobacco hornworm, Manduca sexta, which is related to the vertebrate cellular retinoic acid binding proteins (CRABPs). CRABPs are members of the superfamily of lipid binding proteins (LBPs) and are thought to mediate the effects of retinoic acid (RA) on morphogenesis, differentiation, and homeostasis. This discovery of a Manduca sexta CRABP (msCRABP) demonstrates the presence of a CRABP in invertebrates. Compared with bovine/murine CRABP I, the deduced amino acid sequence of msCRABP is 71% homologous overall and 88% homologous for the ligand binding pocket. The genomic organization of msCRABP is conserved with other CRABP family members and the larger LBP superfamily. Importantly, the promoter region contains a motif that resembles an RA response element characteristic of the promoter region of most CRABPs analyzed. Three-dimensional molecular modeling based on postulated structural homology with bovine/murine CRABP I shows msCRABP has a ligand binding pocket that can accommodate RA. The existence of an invertebrate CRABP has significant evolutionary implications, suggesting CRABPs appeared during the evolution of the LBP superfamily well before vertebrate/invertebrate divergence, instead of much later in evolution in selected vertebrates.

Relation of LDL size to the insulin resistance syndrome and coronary heart disease in American Indians. The Strong Heart Study

Small, dense LDL has been shown to be associated with the insulin resistance syndrome and coronary heart disease (CHD). We examined the distribution of LDL size and phenotype within a population-based sample of American Indians to determine the relationships with prevalent CHD and to examine associations with hyperinsulinemia and other components of the insulin resistance syndrome. Data were available for 4505 men and women between 45 and 74 years of age who are members of 13 American Indian communities in three geographic areas. Diabetes, CHD, and CHD risk factors were assessed by standardized techniques, and LDL size was measured by gradient gel electrophoresis. LDL size was smaller in men than in women and in individuals with diabetes than in those without diabetes. In multivariate analysis, LDL size was significantly related to several components of the insulin resistance syndrome, including triglycerides (inversely) and HDL cholesterol (positively). Although univariate relations were positive, LDL size was not significantly related to fasting insulin concentrations or body mass index in the multivariate model. LDL size also showed no relationship to apolipoprotein E phenotype. When LDL size was compared in individuals with and without CHD, no significant differences were observed, either in nondiabetic or diabetic individuals. We conclude that LDL size is most strongly related to lipoprotein components of the insulin resistance syndrome, especially plasma triglycerides. However, in this population with low LDL, it is not related to cardiovascular disease.

The effects of chronic smoking on the fibrinolytic potential of plasma and platelets

We studied tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) in healthy individuals divided by smoking habit into current smokers, former smokers and non-smokers (who had never smoked). Plasma PAI-1 antigen was significantly higher in smokers than in non-smokers with intermediate levels in former smokers. A similar trend was observed for plasma PAI activity but this did not reach statistical significance. Platelet PAI-1 and plasma t-PA were not significantly different when comparing the three groups. After venous occlusion t-PA rose significantly in all groups; no significant change in plasma PAI-1 was observed. The ratio of t-PA to PAI-1 in plasma was similar in non-smokers and former smokers but lower in smokers, suggesting that there is at least partial restoration of plasma fibrinolytic potential after smoking cessation. Plasma PAI-1 antigen and PAI activity correlated with estimated pack-years of cigarettes smoked among smokers and former smokers. When all subjects were studied collectively, plasma PAI-1 correlated strongly with plasma t-PA and triglycerides: plasma t-PA also correlated strongly with triglycerdes. We conclude that chronic smoking is associated with impaired fibrinolysis in plasma and that this largely reflects elevated plasma PAI-1 in smokers. Smoking does not appear to affect the response to venous occlusion. The postulated effect of chronic smoking on plasma PAI-1 may be mediated by the influence of smoking on triglycerides and insulin resistance. Stopping smoking appears to return impaired fibrinolysis towards normal. Smoking does not quantitatively affect the platelet pool of PAI-1. Smoking habit should be controlled for in clinical analyses of PAI-1 and t-PA.

Acute myelocytic leukaemia presenting as anergic pulmonary tuberculosis

This case report describes a patient with anergic pulmonary tuberculosis who presented with pyrexia of unknown origin and vasculitis. He did not exhibit any pulmonary symptoms at his initial presentation and developed acute myelocytic leukaemia, a recognised association, during the subsequent course of his illness.

Prednisolone metasulphobenzoate foam retention enemas suppress the hypothalamo-pituitary-adrenal axis

BACKGROUND

Corticosteroid enemas represent effective treatment for ulcerative proctitis, but absorption into the systemic circulation may have undesirable metabolic consequences. Prednisolone metasulphobenzoate, a lipophobic corticosteroid derivative, is designed to be absorbed poorly through the recto-sigmoid mucosa, but the effects of foam enema preparations upon the hypothalamo-pituitary-adrenal axis have not been examined.

METHODS

Nine patients suffering from active ulcerative proctitis underwent four weeks of therapy with prednisolone metasulphobenzoate foam enemas. The hypothalamo-pituitary-adrenal axis, defined using the modified single-dose metyrapone test, glucose homeostasis and lipid profiles were studied before and after treatment.

RESULTS

The hypothalamo-pituitary-adrenal axis was significantly depressed after the treatment period; mean stimulated plasma cortisol concentration fell from 384 +/- 244 (s.d.) to 288 +/- 252 nmol/L, P < 0.02; stimulated mean plasma 11-deoxycortisol concentration fell from 677 +/- 333 to 407 +/- 326 nmol/L, P < 0.01. Mean fasting plasma glucose, insulin, C-peptide, fructosamine and triglyceride concentration were unchanged, whilst the mean serum cholesterol concentrations rose from 5.6 +/- 1.1 to 6.0 +/- 1.2 mmol/L (not significant).

CONCLUSION

Prednisolone metasulphobenzoate foam enemas have significant systemic and endocrine metabolic effects, which could assume importance with long-term therapy.

Physical characteristics of the cerebral big prothoracicotropic hormone from Manduca sexta

The prothoracicotropic hormones (PTTHs) are cerebral peptides that control insect postembryonic development by stimulating the prothoracic glands to synthesize ecdysteroids. In Manduca sexta, the tobacco hornworm, two classes of PTTH are distinguished by their M(r), small (ca. 7 kDa) and big PTTH (ca. 25-30 kDa). Little is known about the physical nature of the PTTHs and this study takes a first step towards defining characteristics of the Manduca big PTTH. The neurohormone has a Stokes radius of 2.59 nm and a sedimentation coefficient of 2.76 S. Based on these data, an M(r) of 29,443.7 and an f/fo of 1.27 were calculated. Combined, the physical data reveal Manduca big PTTH is an asymmetrical acidic homodimeric peptide with intra- and intermolecular disulfide bonds.

The prothoracicotropic hormone (PTTH) of the commercial silkmoth, Bombyx mori, in the CNS of the tobacco hornworm, Manduca sexta

Immunocytochemistry revealed that a Bombyx mori prothoracicotropic hormone (PTTH)-like peptide is expressed by the Manduca sexta big PTTH-producing neurons, the lateral neurosecretory cell group III (L-NSC III). Independent PCR of genomic DNA and a L-NSC III cDNA library yielded products with 99% sequence similarity to the cDNA encoding Bombyx PTTH. This similarity necessitated evaluation of the relationship between Manduca big PTTH and Bombyx PTTH by 1) bioassay of IEF separated Manduca PTTH and 2) direct assessment of Bombyx PTTH biological activity with Manduca prothoracic glands. Together, these studies indicate that Bombyx PTTH and Manduca PTTH are different peptides expressed by the L-NSC III. The possible physiological significance of a Bombyx PTTH-like peptide in Manduca and its coexpression with Manduca big PTTH by the L-NSC III are discussed.

Immunoaffinity purification of the neuropeptide prothoracicotropic hormone from Manduca sexta

The prothoracicotropic hormones (PTTH) are cerebral peptides that control insect postembryonic development by stimulating the prothoracic glands to synthesize ecdysteroids. Using immunoaffinity chromatography and SDS-PAGE, a 25.5 kDa big PTTH has been purified from Manduca sexta. Based upon SDS-PAGE and Western blot analysis, the native form of big PTTH appears to be a dimer with monomers of 16.5 kDa. Four HPLC-separated fragments of this acidic peptide were sequenced and exhibited no sequence similarity with Bombyx mori PTTH. In agreement with this finding, the basic Bombyx PTTH had no PTTH bioactivity in Manduca. One sequenced fragment of the Manduca PTTH is approximately 70% similar to the vertebrate cellular retinoid binding proteins, suggesting these binding proteins may be present in insects.

Collagen shields exacerbate ulceration of alkali-burned rabbit corneas

OBJECTIVE

To determine the impact of collagen shields on ulceration of rabbit corneas after alkali burn.

METHODS

After a 60-second 2N sodium hydroxide burn to rabbit corneas, 24-hour collagen shields were placed on the corneas daily for 21 days; control corneas did not receive collagen shields. The extent of corneal ulceration was documented daily for 21 days by slit-lamp examination of treated and control eyes. Three separate studies were performed using collagen shields from two commercial sources.

RESULTS

In the three studies, corneas in the collagen shield-treated eyes began to ulcerate sooner than those in the control group; the corneas in collagen shield-treated eyes also began to perforate sooner. At 21 days after alkali injury, the mean (+/- SE) corneal ulceration score in the collagen shield-treated rabbits was 4.1 +/- 0.17 (descemetocele formation) compared with 2.7 +/- 0.28 (midstromal ulceration) in controls. This difference was significant at P < .005.

CONCLUSION

Collagen shield treatment results in marked acceleration of corneal ulceration and perforation after alkali injury.

A 28-kDa cerebral neuropeptide from Manduca sexta: relationship to the insect prothoracicotropic hormone

1. A 28-kDa peptide from the brain of the tobacco hornworm, Manduca sexta, was purified via HPLC. The peptide copurified with the insect neurohormone, prothoracicotropic hormone (PTTH), through two HPLC columns. 2. Immunocytochemistry using polyclonal antibodies against the 28-kDa peptide revealed that the peptide was produced in the same protocerebral neurons that produce PTTH. Western blot analysis demonstrated that the 28-kDa peptide and big PTTH are different molecules. 3. A PTTH in vitro bioassay indicated that despite having chromatographic properties similar to those of big PTTH and being produced by the same neurons, the 28-kDa peptide did not have PTTH activity. 4. Amino acid sequence analysis yielded a 27 N-terminal amino acid sequence that had no similarity with known peptides. 5. Immunocytochemical studies revealed that the 28-kDa peptide is present as early as 30% embryonic development and is absent by adult eclosion. This is in contrast to big PTTH, which is expressed throughout the Manduca life cycle. 6. These data suggest that the 28-kDa peptide is another secretory phenotype of the lateral neurosecretory cell group III (L-NSC III) which may have functions distinct from those for big PTTH or may act synergistically with big PTTH.

Reversible hypertrophic cardiomyopathy associated with nesidioblastosis

An infant with persistent hyperinsulinism had hypertrophic cardiomyopathy that progressed until near-total pancreatectomy was performed. After pancreatectomy the condition resolved. Hyperinsulinism may be a cause of treatable cardiomyopathy.

Modulation of chicken plaque-forming cells by serotonin and dopamine

Serotonin (5-hydroxytryptamine, 5-HT) and dopamine (DA) are endogenous components of the central nervous and endocrine systems of the chicken. To determine the effects of these monoamines on antibody-mediated immunity. New Hampshire chickens of Line UNH 105 were injected intravenously with 5-HT (100 micrograms/kg of body weight) and DA (1 mg/kg of body weight). One milliliter of a 5% SRBC suspension was injected intravenously 30 min later. Both IgM and IgG splenic plaque-forming cells were assayed 5 days after antigen injection. For in vitro studies, spleen lymphocytes from SRBC-primed chicks were incubated with DA and 5-HT followed by quantitation of IgM and IgG plaque-forming cells. The in vivo incubation of splenic lymphocytes with specific antagonists was used to ascertain the presence of monoamine receptors on lymphocytes. The 5-HT significantly enhanced IgM plaque-forming cells compared with controls following in vivo [550 +/- 85 (SE) cells/10(6) splenic lymphocytes versus 359 +/- 44] but not in vitro exposure. The IgG plaque-forming cells were not affected by 5-HT. The DA significantly suppressed IgM plaque-forming cells responses following in vivo (284 +/- 46 versus 499 +/- 66) and in vitro (254 +/- 57 versus 451 +/- 51) exposure. Significant suppression of IgG plaque-forming cells was found in vivo (287 +/- 40 versus 462 +/- 75) and in vitro (153 +/- 36 versus 371 +/- 81) following treatment. Specific DA antagonists, apomorphine and metoclopramide, did not alleviate the in vitro suppressive effect of DA.

A comparison of metformin versus guar in combination with sulphonylureas in the treatment of non insulin dependent diabetes

Twelve non-obese non insulin dependent diabetics whose mean +/- SE fasting blood glucose was 12.9 +/- 0.9 mmol/l despite maximal doses of sulphonylureas, received 8 weeks of guar (5 g tid before meals) and 8 weeks of metformin (0.5 g tid) following a six week washout period, in a cross-over design. Guar significantly lowered fasting cholesterol and triglyceride concentrations but did not alter glucose concentrations. Conversely, metformin significantly reduced fasting and post-prandial glucose concentrations but had no influence on plasma lipids.

Ghost-cell tumor of the optic chiasm. Primary CNS lymphoma

A case of steroid-responsive malignant lymphoma of the optic chiasm is reported in a 58-year-old woman presenting with subacute vision loss, headaches, and decreased hearing. The exquisite sensitivity of magnetic resonance imaging (MRI) of the parasellar area and the usefulness of MR-directed stereotactic biopsy in identifying a chiasmatic lesion are shown. Primary CNS lymphomas are briefly reviewed. Ophthalmologists will be asked to evaluate patients with malignant lymphoma of the optic chiasm with increased frequency in the future, as CNS lymphomas are expected to be the most common neurological neoplasm by 1991.

Effect of alpha-glucosidase inhibition on glucose profiles in insulin dependent diabetes

A single-blind comparison of the effectiveness of miglitol (BAY-m-1099) and placebo in controlling postprandial hyperglycaemia was performed in 13 insulin dependent diabetics. Each subject received placebo and miglitol for four weeks, with an intervening two week placebo (washout) period, and underwent a 9.5 hr glycaemic profile after each four week treatment period. The area under the glucose curve was significantly (p less than 0.01) reduced by miglitol although no reduction in fasting blood glucose, HbA1, plasma lipids, insulin dosage or weight was observed. Side effects were not appreciably more common when patients received miglitol than when receiving placebo.

Effectiveness of acarbose, an alpha-glucosidase inhibitor, in uncontrolled non-obese non-insulin dependent diabetes

The effect of acarbose, an alpha-glucosidase inhibitor, on glycaemic control, was compared with placebo in a double-blind, randomised, group comparison study during 16 weeks in 20 non-obese non-insulin dependent diabetic patients in whom sulphonylurea treatment had been withdrawn. There was significant deterioration in glycaemic control as assessed by HbA1 following withdrawal of the sulphonylurea. There was no significant improvement in HbA1 between weeks 0 and 16 in either the acarbose (11.3% and 12.4% respectively) or the placebo group (10.6% and 12.2% respectively). In both the acarbose and placebo treated groups fasting glucose and insulin concentrations were unaltered. This study also suggests that acarbose was not an effective substitute for sulphonylureas in non-obese Type 2 diabetes uncontrolled by diet alone.

Reversal of insulin resistance in type 1 diabetes following initiation of insulin treatment

The biological action and pharmacokinetics of insulin were assessed in nine type 1 (insulin-dependent) diabetic patients before and after 3 months conventional insulin treatment, and in seven age and weight-matched non-diabetic controls, by means of the euglycaemic insulin clamp technique. The mean (+/- S.E.) metabolic clearance rate of insulin, when infused at 1 mU/kg/min, was similar in untreated and treated diabetic patients and in controls (22.7 +/- 2.0, 19.3 +/- 3.8, and 22.9 +/- 3.3 ml/kg/min) but, when infused at 6 mU/kg/min, was greater (p less than 0.01 and less than 0.01) in untreated patients (18.0 +/- 2.5 ml/kg/min) than in treated patients (11.5 +/- 1.4 ml/kg/min) and controls (12.7 +/- 1.3 ml/kg/min). Insulin-mediated glucose disposal was reduced (p less than 0.01 and less than 0.01) at insulin infusion rates 1 and 6 mU/kg/min in untreated patients (18.5 +/- 1.9 and 33.8 +/- 4.5 mumol/kg/min) when compared with controls (35.8 +/- 3.4 and 62.0 +/- 4.7 mumol/kg/min) and was improved (p less than 0.01 and less than 0.01) following insulin treatment (36.1 +/- 4.6 and 64.8 +/- 4.2 mumol/kg/min). Daily insulin requirement fell by 33% following 3 months insulin treatment with improvement in mean HbA1 from 16.3 +/- 0.7 to 8.2 +/- 0.4%, but without significant increase in endogenous insulin secretion. The 'honeymoon phenomenon', which has traditionally been attributed exclusively to resurrection of endogenous insulin release, may also be related to normalization of insulin action following institution of insulin treatment.

Vitiligo in diabetes mellitus

We studied the association between vitiligo and diabetes mellitus, and found that vitiligo is associated with insulin-dependent diabetes but not with non-insulin-dependent diabetes. This gives further weight to the theory that vitiligo is an autoimmune disease.

Influence of insulin antibodies on pharmacokinetics and bioavailability of recombinant human and highly purified beef insulins in insulin dependent diabetics

Sixteen insulin dependent diabetics of long standing, with undetectable fasting plasma C peptide concentrations, and eight non-diabetic controls were each infused intravenously with biosynthetic human and highly purified beef insulin (1 mU/kg/min) while euglycaemia was maintained by a Biostator. No difference was observed between the two insulins in respect of insulin pharmacokinetics or biological action. The diabetics showed appreciable insulin resistance, manifested by a 40% reduction in the rate of insulin mediated glucose disposal, which was unrelated to the presence of insulin antibodies. Insulin binding antibodies, however, increased insulin's clearance rate and distribution space and prolonged its pharmacological and biological half lives. The rate at which insulin action was lost, after an intravenous infusion, was more rapid in diabetics without insulin antibody binding than in controls. In respect of their influence on insulin pharmacokinetics, moderate concentrations of insulin antibodies may be of positive advantage to all diabetics without endogenous insulin secretion and are not responsible for the insulin resistance of type 1 diabetes.

Insulin action and pharmacokinetics in insulin treated diabetics during the third trimester of pregnancy

Insulin action and pharmacokinetics were compared, using the euglycaemic insulin clamp technique, in seven insulin-treated diabetics during the third trimester of pregnancy and one to three weeks post-partum. At an insulin infusion rate of 1 mU/kg/min, insulin mediated glucose disposal was significantly greater (p less than 0.02) following delivery (1.194 +/- 0.138 mmol/m2/min) than in pregnancy (0.761 +/- 0.072 mmol/m2/min) and the rate of decline in insulin mediated glucose disposal, at the end of the insulin infusion, was significantly greater (p less than 0.02) following delivery (24.78 +/- 4.22 mumol/m2/min2) than in pregnancy (15.17 +/- 2.00 mumol/m2/min2). The metabolic clearance rate, distribution space and pharmacological half-life of insulin were not significantly altered by pregnancy. These findings show that the third trimester of pregnancy is associated with steady state insulin resistance accompanied by a reduced rate of insulin deactivation, but normal insulin pharmacokinetics.

A comparison of the biological actions and pharmacokinetics of intravenously infused highly purified beef and biosynthetic human insulins in normal man

By means of the euglycaemic insulin clamp technique the rate of insulin-mediated peripheral glucose disposal (GDR) was compared in response to intravenous infusions of highly purified beef insulin (BI) and biosynthetic human insulin (BHI), infused at 1 and 6 mU/kg/min, in healthy volunteers. The metabolic clearance rates of BI and BHI were similar at the lower insulin infusion rate and were both greater than those observed at the higher insulin infusion rate, which were also similar, implying the process of insulin clearance to be saturable. The GDRs were similar in response to infusions of BI and BHI at each insulin infusion rate. The rates of insulin deactivation were similar, having discontinued BI and BHI infusions at 1 mU/kg/min.

Glycosylated haemoglobin and serum insulin antibodies in type I diabetes

Type 1 diabetics receiving once (Group 1, n = 72) and twice (Group 2, n = 48) daily subcutaneous injections of conventional beef insulin were compared, on a cross-sectional basis, in respect of insulin antibody binding by serum and total glycosylated haemoglobin (HbA1). Patients in Group 1 had higher insulin antibody binding (25.2 +/- 15.8% vs 17.0 +/- 13.9%; p less than 0.01) and higher HbA1 levels (12.5 +/- 2.0% vs 11.0 +/- 1.8%; p less than 0.001) than patients in Group 2. An inverse correlation (tau = -0.28, p less than 0.01) was observed between HbA1 and insulin antibody binding in C-peptide non-secretors of Group 1 but not in Group 1 C-peptide secretors, nor in C-peptide secretors and/or non-secretors of Group 2. It is suggested that in Type 1 diabetics who receive a single daily insulin injection and who have no endogenous insulin secretion, insulin antibodies may aid glycaemic control by prolonging insulin action.

Platelet and coagulation factors in proliferative diabetic retinopathy

Plasma beta-thromboglobulin, platelet factor 4, fibrinogen, fibrinopeptide A, antithrombin III, factor VIII related antigen, alpha 2-macroglobulin, platelet count, and total glycosylated haemoglobin were measured in three well matched groups of subjects: non-diabetic controls, diabetics without retinopathy, and diabetics with proliferative retinopathy. beta-thromboglobulin and platelet factor 4 concentrations were significantly higher in the diabetics with retinopathy than in the controls and platelet factor 4 was also increased in the diabetics without retinopathy compared with controls. Fibrinogen concentration was raised in diabetics without retinopathy compared with controls, diabetics with retinopathy compared with controls, and diabetics with retinopathy compared with those without. Fibrinopeptide A concentration did not differ significantly between groups. Antithrombin III levels were increased in diabetics with retinopathy compared with controls, and in diabetics with retinopathy compared with those without. Factor VIII related antigen values were higher in both the diabetic groups when compared with the controls. Fibrinopeptide A concentration correlated with both beta-thromboglobulin and platelet factor 4 in each of the three groups. Haemostatic abnormalities in diabetes have been shown, although a hypercoagulable state has not been confirmed. These changes in platelet and coagulation function may be secondary to the development of microvascular disease and their role in the pathogenesis of retinopathy remains uncertain.

The acute and chronic effects of sulfonylurea therapy in type II diabetic subjects

Although sulfonylurea agents have been used in the clinical management of type II diabetes (non-insulin-dependent diabetes mellitus, NIDDM) for over two decades, the mechanisms responsible for their hypoglycemic action remain controversial. We have quantitated glycemic control, endogenous insulin secretion in response to mixed meals, adipocyte insulin binding, insulin-mediated peripheral glucose disposal, and basal hepatic glucose output in 17 type II diabetic subjects before and after 3 mo of therapy with the second-generation, sulfonylurea compound glyburide in an attempt to identify the factors responsible for the clinical response to the drug. In addition, 9 subjects were treated for an additional 15 mo to see if the response to the drug changed with time. The mean fasting serum glucose level fell from an initial value of 264 +/- 17 mg/dl to 178 +/- 16 mg/dl after 3 mo of drug therapy. Endogenous insulin secretion increased in all subjects, but the increase was most marked in those subjects who continued to exhibit fasting hyperglycemia (fasting serum glucose greater than 175 mg/dl) after 3 mo of therapy. Adipocyte insulin binding was unchanged after 3 mo of therapy, while the maximal rate of peripheral glucose disposal was increased by 23%, indicating enhancement of peripheral insulin action at a postreceptor site(s). Basal hepatic glucose output showed a significant correlation with the fasting serum glucose level both before and after therapy (r = 0.86, P less than 0.001) and fell from 141 +/- 12 mg/m2/min before therapy to 107 +/- 11 mg/m2/min after 3 mo of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of in vivo insulin resistance in controlled insulin-dependent, type I, diabetic patients

Although type I diabetic patients are clearly insulin deficient, it is unclear whether they have normal in vivo sensitivity to insulin. Recent studies which suggested that insulin resistance is a common feature of insulin-dependent diabetics have not taken into account their degree of metabolic control or the presence of circulating antibodies. In the present study, we performed multiple euglycemic glucose clamp studies to construct insulin dose-response curves in 5 well controlled and 5 poorly controlled type I diabetic patients and 21 age-matched normal subjects. Each study was performed on a separate day at insulin infusion rates of 15, 40, 120, 240, or 1200 mU/M2 X min. During the 40 and 120 mU/M2 X min infusions, steady state insulin levels of 96 +/- 8 (+/- SE) and 285 +/- 27 microU/ml respectively, were achieved within 25 min in normal subjects. In contrast, diabetic subjects did not achieve steady state insulin levels (62 +/- 8 and 212 +/- 16 microU/ml) until 90 min of infusion, and insulin antibodies were detectable in the serum of all these patients. The dose-response curve for insulin stimulation of glucose disposal in well controlled diabetic subjects was comparable to that in normal subjects, with half-maximally effective insulin levels of 84 microU/ml in the diabetic patients compared to 70 microU/ml in normal subjects and virtually identical maximal rates of glucose disposal (433 +/- 11 vs. 411 +/- 17 mg/M2 X min in controls). In contrast, the dose-response curve for poorly controlled diabetic subjects was significantly right-shifted (half-maximally effective insulin level, 112 microU/ml), with marked reduction in the maximal glucose disposal rate (324 +/- 25 vs. 411 +/- 17 mg/M2 X min in normal subjects). Basal hepatic glucose output was increased in both poorly controlled and well controlled type I diabetic patients (132 +/- 7 and 101 +/- 16 mg/M2 X min, respectively) compared to normal subjects (76 +/- 7 mg/M2 X min). However, during each insulin infusion, hepatic glucose output was virtually 100% suppressed in all 3 groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Non-insulin-treated ICA positive and negative diabetics are equally insulin resistant

Insulin action was assessed in 5 cytoplasmic islet cell antibody (ICA) positive non-diabetics, 8 ICA positive (type I) non-insulin-treated diabetics, 7 ICA negative insulin-treated diabetics by measurement of steady state plasma glucose (SSPG) levels during a combined intravenous infusion of propranolol, adrenaline, glucose and insulin. SPPG values of ICA positive and negative non-diabetics were similar and their combined value (4.0 +/- 0.5 mmol/l) was significantly lower (p less than 0.01 and less than 0.01) than those (11.5 +/- 1.9 and 11.3 +/- 2.2 mmol/l) of ICA positive and negative diabetics, indicating that both groups of diabetics were similarly insulin resistant. Similar correlations were observed between SSPG and HbA1 levels when considering all ICA positive subjects (r = 0.89, p less than 0.001) and all ICA negative subjects (r = 0.73, p less than 0.01). Conventional insulin treatment (2.6 months) in 4 ICA positive diabetics improved insulin action in each case with a reduction in mean SSPG concentration from 14.0 +/- 2.3 to 8.5 +/- 3.4 mmol/l. Thus, ICA positive and negative diabetics, of equivalent degree of carbohydrate intolerance, are equally insulin resistant. Insulin treatment may improve, but appears not to normalise, insulin action in ICA positive (type I) diabetics.

Circulating IgG antibody to protamine in patients treated with protamine-insulins

Sera from patients with different types of protamine-insulin were assayed for IgG antibody to protamine. A high prevalence of circulating antibody was found in patients treated with either bovine isophane insulin (26 out of 28 patients; 26 of whom also had antibodies to insulin), or bovine protamine zinc insulin (27 out of 30 patients; all 30 had antibodies to insulin). In sera from 24 patients treated with highly purified porcine isophane insulin, protamine antibody was detected in nine; circulating insulin-antibody was detected in 12 patients, eight of whom had protamine-antibody; in the 12 patients with no detectable antibody to insulin, antibody to protamine was detected in only one (x2 = 8.7, p less than 0.01). This relationship between insulin and protamine antigenicity is of interest as it suggests that the protamine-insulin complex is itself immunogenic.

Natural history of thyroid function in diabetics with impaired thyroid reserve: a four year controlled study

An attempt was made to compare the natural history of thyroid function in 80 diabetics having raised serum TSH concentrations (median 8.9 mU/l, range 5.8-46.3 mU/l) but serum T4 concentrations within the normal range (Group 1), and in 59 diabetics having normal serum TSH (median 1.9 mU/l, range 0.8-4.7 mU/l) and T4 concentrations (Group 2). Thyroid microsomal antibodies were present initially in 65% of patients in Group 1 and 15% of patients in Group 2. By 1981, 59 patients (74%) in Group 1 and 47 patients (80%) in Group 2 had been followed for a mean +/- SD duration of 4.2 +/- 1.8 and 4.2 +/- 1.5 years, respectively. Hypothyroidism developed in 9 patients in Group 1, but none from Group 2. Of patients in Group 1, hypothyroidism developed at a rate of 5% per annum in those with thyroid microsomal antibodies, but only 1% per annum in those without antibodies. Therefore, the risk of development of hypothyroidism is greatest in diabetics having both elevated serum TSH concentrations and thyroid microsomal antibodies and such patients should have regular review of thyroid function. Either risk factor alone appears to be a poor predictor of development of hypothyroidism.

Humoral immunity in type 1 diabetes mellitus: a prospective study

Cytoplasmic islet cell antibodies, as detected by anti-IgG (ICAb), and circulating immune complexes (AgAb), detected by the solid phase C1q test (C1qSP), were evaluated in 153 insulin dependent diabetics (IDD) at diagnosis and subsequently in 88 of these patients who were studied prospectively at regular intervals for up to 3 yr. AgAb detected by the conglutinin (KgBt) and Raji cell (RAJI) techniques were also studied at diagnosis in 34 and 50 diabetics respectively. Normal controls were included in the AgAb studies. Complement fixing islet cell antibodies (CF-ICAb) were evaluated in 30 randomly selected diabetics both at diagnosis and after 6 months. Viral antibodies (VAb) were measured in 30 IDD at diagnosis and in 30 matched controls. Insulin antibodies (IBC) were measured 9 months after diagnosis in 35 diabetics and HLA studies (B8 and B15) performed in 115 patients. In the prospective study the ICAb positivity declined from 50% at diagnosis to 45, 38, 36, 31, 26, 19 and 17% at 1, 3, 6, 9, 12, 24 and 36 months after diagnosis respectively. CF-ICAb were found in 30% of the diabetics at diagnosis and in 23% at 6 months. All patients with CF-ICAb at diagnosis were ICAb positive whilst only 47% of patients with ICAb also had CF-ICAb in the serum. AgAb were found at diagnosis in 35% of patients by C1qSP (p less than 0.001 vs. normals), in 35% by KgBt (p less than 0.001) and in 54% by RAJI (p less than 0.002). Eighty-four patients were studied at diagnosis by more than one AgAb method and of these 57% had at least one positive AgAb result. AgAb by C1qSP declined to less than 20% within 6 months of diagnosis. AgAb, as measured by C1qSP and RAJI techniques, correlated with ICAb at diagnosis whereas there was no correlation with VAb levels, IBC values, nor with the HLA antigens. There was no correlation between AgAb (C1q) and CF-ICAb. HLA B15 positive patients tended to form higher IBC levels than B15 negative patients. Thus, AgAb presence seems to parallel that of ICAb in the early stages of diabetes and both phenomena may be primarily or secondarily involved in the development of the disease.

Familial distribution of thyroid disease and diabetes: further evidence for aetiological heterogeneity of diabetes mellitus

The prevalences of thyroid disease, insulin-dependent and non-insulin-dependent diabetes were compared in first degree relatives of diabetics with and without coexisting autoimmune thyroid disease. Thyroid disease was more common in siblings of diabetics with thyroid disease than in those of diabetics without thyroid disease. Insulin-dependent diabetes was more common in siblings of diabetics with a personal or family history of thyroid disease than in those of diabetics without such a history. The prevalence of non-insulin-dependent diabetes was unrelated to that of thyroid disease but was greater in siblings of non-insulin-dependent diabetics than in those of insulin-dependent diabetics. These findings add further support to the aetiological distinction between insulin-dependent and non-insulin-dependent diabetes and suggest that further heterogeneity exists within the population of insulin-dependent diabetics based on the presence of a personal or family history of thyroid disease.

In vivo deactivation of peripheral, hepatic, and pancreatic insulin action in man

The in vivo deactivation of insulin action has been studied in 10 lean, nondiabetic subjects using a modification of the euglycemic glucose clamp technique. Following cessation of 40- and 120-mU/m2/min insulin infusions, the serum insulin levels fell to one-half their initial values (mean +/- SE) of 126 +/- 7 and 350 +/- 14 microunits/ml in 7 +/- 1 and 8 +/- 1 min, respectively. The mean incremental glucose disposal rates (IGDR) fell more slowly following discontinuation of the 40- and 120-mU/m2/min insulin infusions, so that the time required for the IGDRs to fall to one-half their initial values (D50 IGDR) were were 42 +/- 5 and 78 +/- 1 min, respectively. Mean hepatic glucose output was totally suppressed during the 40- and 120-mU/m2/min insulin infusions, remained completely suppressed following cessation of the infusions for 50 and 80 mi, and subsequently returned to basal levels. The times required for the HGOs to return to one-half their basal levels (R50 HGO) were 59 +/- 8 and 119 +/- 6 min, respectively. The times required for insulin action to decrease to one-half the initial values in the periphery (D50 IGDR) and in the liver (R50 HGO) were correlated with the preceding steady-state glucose disposal rates in individual subjects (r = 0.75, P less than 0.001 and r = 0.58, P less than 0.05, respectively). The suppression of endogenous insulin secretion by exogenous insulin infusions was also studied in 4 subjects during a total of 5 euglycemic glucose clamps; the mean basal serum C-peptide level was 0.67 +/- 0.24 pmol/ml before administration of the exogenous insulin, fell to 0.34 +/- 0.17 pmol/ml during the steady-state phase of the study, and remained suppressed throughout the duration of the deactivation phase of the glucose clamp. Residual pancreatic insulin secretory capacity was demonstrated by a rise in the serum C-peptide level to 1.77 +/- 0.50 pmol/ml at 120 min following a standardized meal given at the conclusion of the deactivation phase of the glucose clamp. These results demonstrate that the deactivation of insulin action in the periphery, liver, and pancreas lags behind the disappearance of insulin from the plasma. The mechanisms responsible for this lag in in vivo deactivation are not known for certain, but may include slower clearance of insulin form tissue compartments than form the plasma, the necessity for the target tissues to generate specific deactivation signals, or a slow rate of decay of saturable steps in the cellular activation process.

Alpha 2-macroglobulin and proliferative retinopathy in type 1 diabetes

Serum alpha 2-macroglobulin (alpha 2m) and total glycosylated haemoglobin (HbA1) concentrations were measured in 110 insulin dependent Type 1 diabetics with minimal or no fundoscopic retinopathy, referred to as non-retinopaths, and in 52 proliferative retinopaths. Proteinuria was recorded in 8 (7%) non-retinopaths and 29 (56%) retinopaths and was accompanied by elevated alpha 2m concentrations in both groups of diabetics but only significantly so in the non-retinopaths. Diabetics without proteinuria showed a significant correlation between alpha 2m concentration and duration of diabetes, HbA1 and age (being higher at extremes of age). Alpha 2m concentrations were significantly higher in retinopaths than in non-retinopaths without proteinuria when allowance was made for the influence of age and duration of diabetes on alpha 2m. This difference may be attributed to the higher HbA, levels found in retinopaths than in non-retinopaths and was no longer evident when account was taken of the prevailing HbA1 concentration in individual patients.

Insulin treatment reverses the insulin resistance of type II diabetes mellitus

Type II diabetic subjects are both insulin-deficient and insulin-resistant. Recent studies suggest that the insulin resistance is due to a combined receptor and postreceptor defect with the postreceptor defect being the predominant lesion. In the present study, we examined the effects of exogenous insulin therapy upon these defects in insulin action in six untreated type II diabetic subjects. Glycemic control and adipocyte insulin binding were measured and in vivo insulin dose-response curves for overall glucose disposal and suppression of hepatic glucose output were constructed before treatment. Following these initial studies, the diabetic subjects were treated with twice-daily injections of regular and NPH purified pork insulin for 14 days and the pretreatment studies repeated. Glycemic control was significantly improved by this treatment regimen. The mean fasting serum glucose level (±SE) fell from 287 ± 20 to 125 ± 13 mg/dl, the mean glycosylated hemoglobin level (± SE) decreased from 14.2 ± 1.1% to 8.3 ± 0.5%, and the mean 24-h urinary glucose excretion (±SE) declined from 65.6 ± 40.3 to 0.6 ± 0. 1 g/24 h. Adipocyte insulin binding did not change significantly during the treatment period. In contrast, the 14-day period of insulin treatment produced a 72% increase (P &lt; 0.005) in the maximal rate of insulin-stimulated glucose disposal, 321 ± 32 mg/M2/min compared with 187 ± 32 mg/M2/min before treatment, indicating that the postreceptor defect in insulin action was significantly ameliorated by insulin treatment. The dose-response curve for insulin-mediated suppression of hepatic glucose output was rightshifted, consistent with the decrease in insulin binding, with no decrease in the maximal effect before treatment and not significantly changed following insulin treatment. In conclusion, the postreceptor defect in insulin-stimulated glucose disposal is largely ameliorated by exogenous insulin treatment, suggesting that this defect in insulin action is an acquired abnormality which is secondary to some aspect of the insulin-deficient state.

HLA antigens and other risk factors in the development of retinopathy in type 1 diabetes

Factors possibly influencing the development of diabetic retinopathy were studied in 112 randomly selected type 1 diabetics having no or minimal retinopathy (group A) and in 82 type 1 diabetics with known severe diabetic retinopathy. The latter comprised those with severe background retinopathy (group B, n = 17) and those having proliferative retinopathy without (group C, n = 38) and with group D, n = 27) diabetic nephropathy. Nonretinopaths (group A) were of similar sex ratio, body weight, and age at diagnosis of diabetes but had been diabetic longer (p less than 0.001) and were thus older (p less than 0.001) than retinopaths (groups B-D). The distribution of HLA antigens of the A, B, and C loci was similar in nonretinopaths and retinopaths with the exception that HLA B7 showed a reduced (p less than 0.05) prevalence in the retinopaths (6% versus 17%) and was singularly underrepresented in group D, where no patients had this antigen. Mean postprandial plasma glucose and HbA1 concentrations were higher (p less than 0.01 and p less than 0.001) and cigarette smoking was more prevalent (p less than 0.01) in the retinopathy groups B-D than in group A. Systolic and diastolic blood pressures were similar in groups A-C, with higher (p less than 0.001) values only in group D. There was no association between insulin antibody binding in the serum or measurable plasma C-peptide immunoreactivity and retinopathy status. The risk of development of diabetic retinopathy in type 1 diabetes may be related to HLA-associated genetic factors and to cigarette smoking.

Glycosylated hemoglobin and its temporal relationship to plasma glucose in non-insulin dependent (type 2) diabetes mellitus

Total glycosylated hemoglobin (HbAI) and random plasma glucose were measured at monthly intervals for 6 mo in 33 non-insulin dependent (type 2) diabetics. The mean HbAI and mean plasma glucose in individual patients over the 6 mo showed a close correlation (p less than 0.001). A significantly higher HbAI (p less than 0.001) for a given plasma glucose was seen in those patients receiving combined chlorpropamide and metformin therapy (n = 14) than in those receiving chlorpropamide alone (n = 19). For each patient correlation coefficients were calculated between plasma glucose and HbAI with time lags of 0.1 and 2 mo. The coefficients with no time lag showed a significant tendency to be positive (p less than 0.01) whereas those with time lags of 1 or 2 mo were not significant. A constant proportional variability of both HbAI and plasma glucose over time was demonstrated, the mean coefficient of variation for HbAI being 8.4 +/- 2.7% and for plasma glucose 22.3 +/- 9.7%. We conclude that HbAI provides an index of plasma glucose control, not during the preceding few months as was previously thought but, during the previous few weeks. In terms of variability from month to month a single HbAI determination was equivalent to approximately the mean of 3 single plasma glucose values.

Effect of a glucosidase inhibitor on the metabolic response of diabetic rats to a high carbohydrate diet, consisting of starch and sucrose, or glucose

The metabolic consequences of the addition of Bay-g-5421 to a diet whose caloric value included 67% carbohydrate, comprising wheat starch (diet A), equal quantities of wheat starch and sucrose (diet B) or glucose (diet C) were studied in lean diabetic and non-diabetic rats. BAY-g-5421 led to a significant (30%) reduction in daily food intake of diabetic and non-diabetic rats fed diets A and B, respectively. In diabetic rats fed diets A and B with Bay-g-5421, daily urinary glucose was diminished ten-fold, while the post-prandial plasma glucose excursions were almost halved. Serum cholesterol, but not triglyceride concentrations, were reduced after five days, by the addition of BAY-g-5421 to diets A or B in non-diabetic rats, and in diabetic rats when the animals fed diets A and B were combined. BAY-g-5421 did not significantly after the food intake, urinary glucose excretion, post-prandial plasma glucose excursions nor serum lipids in diabetic and non-diabetic rats fed diet C. These findings illustrate the therapeutic potential of BAY-g-5421 as an adjunct to the dietary management of diabetes mellitus.

Relationship of glycosylated haemoglobin to C-peptide secretory status and antibody binding of insulin in insulin-dependent diabetes

Diabetic control, assessed by measuring the concentration in venous blood of total glycosylated haemoglobin (HbA1), endogenous insulin secretion, as estimated by the C-peptide response (delta C-P) to intravenous glucagon, and serum beef insulin antibody binding were measured in 50 juvenile onset insulin dependent diabetics (IDDM) receiving a single daily injection of soluble and protamine zinc insulin. The delta C-P correlated inversely with duration of diabetes (tau = -0.27, p less than 0.01) and daily insulin requirement (tau = -0.22, p less than 0.05) in the 50 IDDM studied of whom 28 exhibited a measurable delta C-P. In C-peptide nonresponders, but not in the C-peptide responders, and inverse regression (t = 2.19, p less than 0.05) was observed between beef insulin antibody and HbA1. In the 25 IDDM having the lowest insulin antibody binding, and inverse correlation (tau = 0.36, p less than 0.02) was observed between delta CP and HbA1, which was not found (tau = 0.05) in the remaining 25 IDDM who had the highest insulin antibody binding. These findings suggest that, in the absence of endogenous insulin secretion, diabetic control in IDDM receiving a single daily injection of conventional beef insulin is better in patients with high beef insulin antibody binding. Conversely, in patients with low beef insulin antibody binding, diabetic control appears to be better in those with persisting endogenous insulin secretion.

Receptor and postreceptor defects contribute to the insulin resistance in noninsulin-dependent diabetes mellitus

We have assessed the mechanisms involved in the pathogenesis of the insulin resistance associated with impaired glucose tolerance and Type II diabetes mellitus by exploring, by means of the euglycemic glucose-clamp technique, the in vivo dose-response relationship between serum insulin and the overall rate of glucose disposal in 14 control subjects; 8 subjects with impaired glucose tolerance, and 23 subjects with Type II diabetes. Each subject had at least three studies performed on separate days at insulin infusion rates of 40, 120, 240, 1,200, or 1,800 mU/M2 per min. In the subjects with impaired glucose tolerance, the dose-response curve was shifted to the right (half-maximally effective insulin level 240 vs. 135 microunits/ml for controls), but the maximal rate of glucose disposal remained normal. In patients with Type II diabetes mellitus, the dose-response curve was also shifted to the right, but in addition, there was a posal. This pattern was seen both in the 13 nonobese and the 10 obese diabetic subjects. Among these patients, an inverse linear relationship exists (r = -0.72) so that the higher the fasting glucose level, the lower the maximal glucose disposal rate. Basal rates of hepatic glucose output were 74 +/- 4, 82 +/- 7, 139 +/- 24, and 125 +/- 16 mg/M2 per min for the control subjects, subjects with impaired glucose tolerance, nonobese Type II diabetic subjects, and obese Type II diabetic subjects, respectively. Higher serum insulin levels were required to suppress hepatic glucose output in the subjects with impaired glucose tolerance and Type II diabetics, compared with controls, but hepatic glucose output could be totally suppressed in each study group. We conclude that the mechanisms of insulin resistance in patients with impaired glucose tolerance and in patients with Type II noninsulin-dependent diabetes are complex, and result from heterogeneous causes. (a) In the patients with the mildest disorders of carbohydrate homeostasis (patients with impaired glucose tolerance) the insulin resistance can be accounted for solely on the basis of decreased insulin receptors. (b) In patients with fasting hyperglycemia, insulin resistance is due to both decreased insulin receptors and postreceptor defect in the glucose mechanisms. (c) As the hyperglycemia worsens, the postreceptor defect in peripheral glucose disposal emerges and progressively increases. And (d) no postreceptor defect was detected in any of the patient groups when insulin's ability to suppress hepatic glucose output was measured.

Diabetic control in patients treated with once or twice-daily insulin injections, including a comparison of conventional beef and highly purified pork insulins

Twenty patients were changed from a single daily injection of beef insulin (a mixture of soluble and protamine zinc insulin) to two daily injections (mixtures of soluble and isophane insulins). This was associated with a reduction, one month later, in the concentration of glycosylated haemoglobin (HbA1) and in the degree of late evening glycosuria. A reduction was shown 6 months later in antibody binding of beef and pork insulin by serum. Subsequent conversion to a twice daily regime of highly purified pork insulin was not associated with further improvement in diabetic control, but was associated after 1 month with a reduction in daily insulin dose, and after 5 months with a further reduction in antibody binding of beef and pork insulin by serum. Patients failing to show a C-peptide response to intravenous glucagon had a fall in HbA1 after conversion from a once to a twice daily insulin regime, which correlated inversely with insulin antibody binding estimated at the beginning of the study.