Management of hypertension and renin-angiotensin-aldosterone system blockade in adults with diabetic kidney disease: Association of British Clinical Diabetologists and the Renal Association UK guideline update 2021.

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.

Diabetes and chronic kidney disease: an increasingly common multi-morbid disease in need of a paradigm shift in care.

Diabetes is considered the commonest cause of end-stage renal disease. The increasing incidence of obesity and an ageing population, together, will lead to a greater number of people with diabetes associated with chronic kidney disease that could either be secondary to diabetic nephropathy or of different aetiology. Ageing and obesity influence approaches to the management of diabetes and accurate assessment of kidney disease. People with diabetes and chronic kidney disease consume a disproportionate component of expenditure on medical care. Guidelines on managing diabetes and kidney disease do not recognize the complex multi-morbid nature of the process. In addition to managing glycaemia and monitoring renal function, the assessment and management of cardiovascular disease risk factors and cardiovascular disease itself need to be factored into care. People with diabetes and diabetic nephropathy are more vulnerable to retinopathy and foot complications requiring coordinated care. People with diabetes and chronic kidney disease are more prone to anaemia and metabolic bone disease than those without diabetes at similar stages of chronic kidney disease, further increasing their vulnerability to acute complications from cardiovascular disease, foot emergencies and fractures. People with diabetes and chronic kidney disease are also more prone to hospitalization with infections and acute kidney injury. Given the 30-40% prevalence of kidney disease amongst people with diabetes, potentially >2% of the adult population would fit into this category, making it vital that new surveillance models of supported care are provided for those living with diabetes and kidney disease and for primary care teams who manage the vast majority of such people.

Management of adults with diabetes on the haemodialysis unit: summary of guidance from the Joint British Diabetes Societies and the Renal Association.

Diabetic nephropathy remains the principal cause of end-stage renal failure in the UK and its prevalence is set to increase. People with diabetes and end-stage renal failure on maintenance haemodialysis are highly vulnerable, with complex comorbidities, and are at high risk of adverse cardiovascular outcomes, the leading cause of mortality in this population. The management of people with diabetes receiving maintenance haemodialysis is shared between diabetes and renal specialist teams and the primary care team, with input from additional healthcare professionals providing foot care, dietary support and other aspects of multidisciplinary care. In this setting, one specialty may assume that key aspects of care are being provided elsewhere, which can lead to important components of care being overlooked. People with diabetes and end-stage renal failure require improved delivery of care to overcome organizational difficulties and barriers to communication between healthcare teams. No comprehensive guidance on the management of this population has previously been produced. These national guidelines, the first in this area, bring together in one document the disparate needs of people with diabetes on maintenance haemodialysis. The guidelines are based on the best available evidence, or on expert opinion where there is no clear evidence to inform practice. We aim to provide clear advice to clinicians caring for this vulnerable population and to encourage and improve education for clinicians and people with diabetes to promote empowerment and self-management.

A national survey of the current state of screening services for diabetic retinopathy: ABCD-diabetes UK survey of specialist diabetes services 2006.

The main aims were to ascertain the progress made in the implementation of retinal screening services and to explore any barriers or difficulties faced by the programmes. The survey focused on all the essential elements for retinal screening, including assessment and treatment of screen-positive cases. Eighty-five per cent of screening programmes have a coordinated screening service and 73% of these felt that they have made significant progress. Eighty-five per cent of screening units use 'call and recall' for appointments and 73.5% of programmes follow the National Screening Committee (NSC) guidance. Although many units worked closely with ophthalmology, further assessment and management of screen-positive patients was a cause for concern. The fast-track referral system, to ensure timely and appropriate care, has been difficult to engineer by several programmes. This is demonstrated by 48% of programmes having waiting lists for patients identified as needing further assessment and treatment for retinopathy. Ophthalmology service for people with diabetic retinopathy was provided by a dedicated ophthalmologist in 89.4% of the programmes. Sixty-six per cent of the programmes reported inadequate resources to sustain a high-quality service, while 26% highlighted the lack of infrastructure and 49% lacked information technology (IT) support. In conclusion, progress has been made towards establishing a national screening programme for diabetic retinopathy by individual screening units, with a number of programmes providing a structured retinal screening service. However, programmes face difficulties with resource allocation and compliance with Quality Assurance (QA) standards, especially those which apply to ophthalmology and IT support. Screening programmes need to be resourced adequately to ensure comprehensive coverage and compliance with QA.

Diabetes specialist nurses and role evolvement: a survey by Diabetes UK and ABCD of specialist diabetes services 2007.

AIMS: To review the working practices of UK diabetes specialist nurses (DSNs), specific clinical roles, and to examine changes since 2000. METHODS: Postal questionnaires were sent to lead DSNs from all identifiable UK diabetes centres (n = 361). Quantitative and qualitative data were collected on the specific clinical roles, employment, and continual professional development of hospital and community DSNs, Nurse Consultants and Diabetes Healthcare Assistants. RESULTS: 159 centres (44%) returned questionnaires. 78% and 76% of DSNs plan and deliver education sessions compared with 13% in 2000 with a wider range of topics and with less input from medical staff. 22% of DSNs have a formal role in diabetes research compared with 48% in 2000. 49% of Hospital DSNs, 56% of Community DSNs and 66% of Nurse Consultants are involved in prescribing. 55% of DSNs carry out pump training, 72% participate in ante-natal and 27% renal clinics. 90% of services have independent diabetes nurse-led clinics. 93% of services have a dedicated Paediatric DSN. The mean number of children under the care of each PDSN is 109 (mode 120), which exceeds Royal College of Nursing recommendations. 48% of DSNs have protected time for continuing professional development of staff and 15% have a protected budget. One third of DSNs are on short-term contracts funded by external sources. CONCLUSIONS: The DSN role has evolved since 2000 to include complex service provision and responsibilities including specialist clinics, education of healthcare professionals and patients. The lack of substantive contracts and protected study leave may compromise these roles in the future.

Association of British Clinical Diabetologists (ABCD) and Diabetes-UK survey of specialist diabetes services in the UK, 2006. 1. The consultant physician perspective.

AIMS: To identify the views and working practices of consultant diabetologists in the UK in 2006-2007, the current provision of specialist services, and to examine changes since 2000. METHODS: All 592 UK consultant diabetologists were invited to participate in an on-line survey. Quantitative and qualitative analyses of responses were undertaken. A composite 'well-resourced service score' was calculated. In addition to an analysis of all respondents, a sub-analysis was undertaken, comparing localities represented both in 2006/2007 and in 2000. RESULTS: In 2006/2007, a 49% response rate was achieved, representing 50% of acute National Health Service Trusts. Staffing levels had improved, but remained below recommendations made in 2000. Ten percent of specialist services were still provided by single-handed consultants, especially in Northern Ireland (in 50% of responses, P = 0.001 vs. other nations). Antenatal, joint adult-paediatric and ophthalmology sub-specialist diabetes services and availability of biochemical tests had improved since 2000, but access to psychology services had declined. Almost 90% of consultants had no clinical engagement in providing community diabetes services. The 'well-resourced service score' had not improved since 2000. There was continued evidence of disparity in resources between the nations (lowest in Wales and Northern Ireland, P = 0.007), between regions in England (lowest in the East Midlands and the Eastern regions, P = 0.028), and in centres with a single-handed consultant service (P = 0.001). Job satisfaction correlated with well-resourced service score (P = 0.001). The main concerns and threats to specialist services were deficiencies in psychology access, inadequate staffing, lack of progress in commissioning, and the detrimental impact of central policy on specialist services. CONCLUSIONS: There are continued disparities in specialist service provision. Without effective commissioning and adequate specialist team staffing, integrated diabetes care will remain unattainable in many regions, regardless of reconfigurations and alternative service models.

Reversal of shortened platelet survival in rats by the antifibrinolytic agent, epsilon aminocaproic acid.

Platelet survival in rabbits and rats is shortened by placing indwelling catheters in the aorta; this shortening appears to be at least partly related to the extent of vessel wall injury and platelet interaction with the repeatedly damaged wall. Treatment of rabbit platelets with plasmin and other proteolytic enzymes in vitro shortens their survival when they are returned to the circulation. Because platelets may be exposed to plasmin and other proteolytic enzymes in rabbits and rats with indwelling aortic catheters, we examined the effect of epsilon-aminocaproic acid (EACA) on platelet survival in rats. At a dose of 1 g/kg every 4 h, EACA significantly reduced whole blood fibrinolytic activity and prolonged the shortened platelet survival in rats with indwelling aortic catheters. Mean platelet survival for untreated rats with indwelling aortic catheters was 38.6 +/- 1.9 h, and for rats treated with EACA, 53.8 +/- 3.8 h. Scanning electron microscopy showed that the injured vessel wall of these animals was mainly covered with platelets and fibrin, whereas in control animals that did not receive EACA, the injured surface was mainly covered with platelets and little fibrin was observed. Thus shortened platelet survival during continuous vessel wall injury may result from the local generation of plasmin or the release of proteolytic enzymes at sites where platelets (and possibly leukocytes) interact with the vessel wall.

Platelet abnormalities in diabetes mellitus.

Although platelets can contribute to atherosclerosis and its thromboembolic complications in the nondiabetic population, the role of platelets in enhanced vascular disease in the diabetic population remains unclear. Most studies indicate that platelet function in vitro is enhanced in platelets from people and animals with diabetes, and the mechanisms are being identified. There remains some controversy about whether platelet changes occur before, and therefore could contribute to, vascular complications or whether they are secondary to vascular disease. It is possible that only intervention trials to determine if inhibiting platelet function limits the progression of vascular disease in diabetic patients will definitively answer this question. The earlier premise that enhanced activity of the arachidonate pathway is responsible for the hypersensitivity of platelets from diabetic humans needs to be modified to recognize that additional mechanisms are involved in platelet activation and are modified in people with diabetes and also that altered activity of the arachidonate pathway may reflect changes in earlier pathways involved in platelet activation. Clearly, alterations in these nonarachidonate pathways need to be taken into account when considering the appropriate antiplatelet agents to use in intervention trials. Information about whether hypersensitivity of platelets from people with diabetes persists in vivo and, if so, how this influences platelet-vessel wall interactions and thrombotic tendencies needs to be pursued more intensely in suitable animal models so that the theories developed from studies in vitro can be tested in the more complex environment in vivo. These are important areas for research in the future.

Do platelets have anything to do with diabetic microvascular disease?

It has been postulated that abnormal platelet and endothelial function may contribute to microangiopathy in diabetes mellitus. If this proposal is correct, alterations in platelet and endothelial function should be found before the appearance of vascular disease in insulin-dependent patients and in animal models of diabetes mellitus. This appears to be the case for the following: platelet aggregation, increased platelet production of the proaggregatory prostaglandin metabolite thromboxane, decreased endothelial production of the antiaggregatory prostaglandin prostacyclin, and decreased platelet survival. Insulin therapy will return some of these findings to normal. Platelet-plasma interactions that promote platelet aggregation and increased plasma levels of the platelet-specific protein beta-thromboglobulin have been reported in insulin-dependent diabetic patients who have not manifested vascular complications as well as in those with vascular complications. It has now been demonstrated in animal models that platelet microthrombi are found in small retinal vessels after months of experimental diabetes. Collectively, these findings demonstrate that alterations in platelet and endothelial function that favor thrombosis occur early in the diabetic state and may contribute to microvascular disease. There are several ongoing studies of antiplatelet agents in diabetic vascular disease that will provide clinical evidence bearing on the major postulate. Until these and other studies are completed, the platelet-endothelial story remains an attractive hypothesis in the genesis of diabetic microvascular disease.

Reduced membrane fluidity in platelets from diabetic patients.

Platelets from diabetic patients are hypersensitive to agonists in vitro. Membrane fluidity modulates cell function, and reduced membrane fluidity in cholesterol-enriched platelets is associated with platelet hypersensitivity to agonists, including thrombin. Decreased membrane fluidity of these platelets is attributed to an increased cholesterol-phospholipid molar ratio in platelet membranes. We examined the response of platelets from diabetic subjects to thrombin, platelet membrane fluidity, and platelet cholesterol-phospholipid molar ratio. Twelve poorly controlled diabetic subjects were compared with 12 age- and sex-matched control subjects. In response to a low concentration of thrombin, mean values for release of [14C]serotonin from washed prelabeled platelets were not significantly different between diabetic and control subjects, but in 8 of 12 diabetic subjects, the release response was greater than in their paired control subjects. Mean steady-state fluorescence polarization values in 1,6-diphenyl-1,3,5-hexatriene-labeled platelets prepared from diabetic subjects were significantly greater than in control subjects; this indicates a decreased membrane fluidity in platelets from diabetic subjects. Total or very-low-density (VLDL), low-density (LDL), or high-density (HDL2, HDL3) lipoprotein cholesterol concentrations in plasma were not significantly different between groups; however, the ratio of VLDL + LDL to HDL2 + HDL3 was significantly greater in diabetic than in control subjects. There was no difference in the total platelet cholesterol-phospholipid molar ratio between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Relative clinical usefulness of glycosylated serum albumin and fructosamine during short-term changes in glycemic control in IDDM.

Serial changes in glycosylated blood proteins and direct measures of glycemia were studied in 100 subjects with insulin-dependent diabetes mellitus (IDDM) over a 6-wk period while attempts were made to improve glycemic control. All measures of glycemic control improved significantly (P less than .001). Mean +/- SE glycosylated hemoglobin (HbA1) fell from 9.1 +/- 0.2 to 8.0 +/- 0.1%, glycosylated serum albumin (GSA) from 9.8 +/- 0.4 to 7.3 +/- 0.3%, and fructosamine from 3.92 +/- 0.08 to 3.42 +/- 0.07 mM. Fasting blood glucose levels fell from 11.1 +/- 0.6 to 8.1 +/- 0.7 mM mean blood glucose levels from 12.5 +/- 0.3 to 8.8 +/- 0.03 mM, and the M value from 118 +/- 7 to 40 +/- 3 U. Mean percentage changes in direct measures of glycemia (32-66%) and GSA (29%) were greater than for fructosamine (11%) or HbA, (12%) levels (P less than .001). Furthermore, the correlation between the change in GSA and changes in direct measures of glycemia over the initial 2-wk period was significantly different from the corresponding correlations between direct measures of glycemia and fructosamine over this period (P less than .05-.01). Changes in GSA also correlated more closely than HbA1 or fructosamine did with direct measures of glycemia after 4 and 6 wk. The Spearman rank-correlation coefficient (rs) of absolute changes in GSA, fructosamine, and HbA1 after 2-6 wk ranged from 0.27 to 0.57, confirming that the three measures responded differently to changing glycemic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of early diabetic nephropathy on very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL) composition.

The procedure of discontinuous gradient ultracentrifugation (DGU) was used to characterize the influence of early diabetic nephropathy on the composition of very low density lipoprotein (VLDL, flotation density 60-400 Svedberg (Sf) units), low density lipoprotein (LDL, flotation density 0-12 Sf) and subfractions of intermediate density lipoprotein (IDL1 and IDL2, 20-60 and 12-20 Sf, respectively). Forty-six subjects with type 1 (insulin-dependent) diabetes and serum creatinine, less than 140 mumol/l were studied, of whom 23 consistently had normal rates of albumin excretion (AER less than 15 micrograms/min), and 23 had persistent albuminuria (AER 20.0-960.6 micrograms/min). The two groups were similar with respect to total serum lipids, glycaemic control, age and body mass. The composition (lipid, protein and phospholipid) and mass of VLDL, LDL and IDL2 was not appreciably altered by early nephropathy, but free and total cholesterol concentration in IDL1 (Sf 20-60) was increased (total cholesterol 0.68 (0.09) (mean (SE)) vs. 0.47 (0.07) mmol/l, and free cholesterol 0.27 (0.04) vs. 0.17 (0.03) mmol/l, both P less than 0.05). The explanation of these findings was probably an accumulation in the circulation of the remnants of chylomicron metabolism and/or intermediates in the conversion from VLDL to IDL1. In addition, there was a decrease in serum high density lipoprotein (HDL) cholesterol in early nephropathy (1.27 (0.06) vs. 1.38 (0.10) mmol/l, P less than 0.05), due to a decrease in the HDL2 cholesterol subfraction (P less than 0.05). These findings may in part explain the increased risk of premature atherosclerosis associated with the development of albuminuria.

Thrombin binding to platelets from hypercholesterolaemic rats.

Platelets from rats made hypercholesterolaemic with a diet enriched with milk fat and cholesterol and containing taurocholate to promote hypercholesterolaemia aggregated more extensively to a low concentration of thrombin than platelets from rats given a milk fat-enriched diet containing sitosterol. Total and specific binding of thrombin to platelets from hypercholesterolaemic rats was significantly greater than in controls when expressed per mg platelet protein, per mumol platelet cholesterol, or per unit relative surface area. Total and specific binding of thrombin per platelet were not different between the groups. However, platelets from hypercholesterolaemic rats had less protein and cholesterol, were smaller and had less surface area than control platelets; platelet cholesterol content expressed per mg platelet protein was not different. Thus, the increase in thrombin-binding to the smaller platelets from hypercholesterolaemic rats during the first 10 s after its addition may be responsible, at least in part, for the hypersensitivity of these platelets to thrombin.

The effect of dietary saturated fat and cholesterol on platelet function, platelet survival and response to continuous aortic injury in rats.

Induction of hypercholesterolemia in rats by diets containing milk fat, cholesterol and taurocholate caused increased sensitivity of platelets to thrombin-induced aggregation and release, but not to ADP- or collagen-induced aggregation or release. This hypersensitivity to thrombin persisted in the presence of CP/CPK to convert released ADP to ATP, and aspirin to block formation of thromboxane A2. The increased sensitivity of platelets to thrombin in hypercholesterolemic animals was associated with an increase in 18:1 omega 9, 18:2 omega 6 and 20:3 omega 6 and a decrease in 20:4 omega 6 and 22:4 omega 6 in their phospholipids. Hypercholesterolemic animals also had a shortened platelet survival that did not appear to be due to an alteration in the lipid composition of the platelets. The diet-induced changes in platelet function were not associated with enhanced thrombosis in animals with indwelling aortic catheters, but were associated with increased platelet accumulation on the exposed subendothelium.

Effect of the amount and type of dietary fat on platelet function, platelet survival and response to continuous aortic injury in rats.

The effect of giving diets containing 1.5 or 16% safflower or corn oil or 16% milk fat for 15 weeks on changes in the fatty acid composition of platelet phospholipids, in vitro platelet function, platelet survival and thrombosis was examined in rats. The mean plasma cholesterol concentration was not different among the groups. Diets containing 1.5% safflower or corn oil or 16% milk fat were associated with a decrease in 18:2n - 6 and an increase in 18:1n - 9 and the 20:4n - 6/18:2n - 6 ratio in the platelet phospholipids compared with the 16% safflower or corn oil diets. The 16% milk fat diet was associated with an increase in 14:0, 20:3n - 9, 22:3n - 9 and a decrease in 22:4n - 6 in platelet phospholipids compared with the other groups. There were no differences among the groups in the sensitivity of washed platelets to ADP-, thrombin- or collagen-induced aggregation, or thrombin- or collagen-induced release of granule contents or loss of arachidonate from platelet phospholipids. Platelet survival and turnover in rats given the diets were not different among the groups. In response to indwelling aortic catheters neither the percentage reduction in platelet survival nor the platelet accumulation on injured aortae and catheters were different among the groups. No macroscopic thrombi were seen in rats given any of the diets. The results of these studies provide no evidence that diet-induced alterations in fatty acid content (increases in 18:1n - 9, 20:3n - 9, 22:3n - 9, 20:3n - 6, and 20:4n - 6/18:2n - 6 ratio and a decrease in 22:4n - 6) of platelet phospholipids modify in vitro platelet function, platelet survival or turnover or influence thrombosis in rats.

Effects of treatment of hypertriglyceridaemia with gemfibrozil on serum lipoproteins and the transfer of cholesteryl ester from high density lipoproteins to low density lipoproteins.

Lipoprotein composition and cholesterol esterification, before and after treatment with gemfibrozil, have been examined in the fasting and postprandial state in nine patients with primary hypertriglyceridaemia who participated in a double-blind, placebo controlled study. After 8 weeks of treatment fasting serum triglycerides were reduced significantly from 6.05 mmol/l (range 2.48-10.99 mmol/l) to 1.76 mmol/l (range 1.16-11.90 mmol/l) (P less than 0.001). This was mainly due to a decrease in the triglyceride content of the Sf 12-20, 60-400 and Sf greater than 400 lipoprotein fractions (P less than 0.05). The Sf 0-12 fraction showed an increase in cholesteryl ester, free cholesterol, phospholipids and protein. Consistent with these findings there was a net increase in the mass concentration of the Sf 0-12 fraction (P less than 0.05) and a decrease in that of small very low density lipoproteins (Sf 20-60) (P less than 0.05). In the 8 patients in whom it was measured there was a 40% reduction in the rate at which cholesteryl esters derived from radiolabelled-free cholesterol appeared in very low density lipoprotein (VLDL) and low density lipoprotein (LDL) measured in an in vitro system (P less than 0.02), but serum lecithin:cholesterol acyl transferase (LCAT) activity was unchanged. At the end of each treatment phase (placebo or gemfibrozil) patients were given a mixed meal containing 100 g of fat. Treatment with gemfibrozil resulted in a reduction in serum triglyceride concentrations at all time points for at least 5 h after the meal (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Microalbuminuria and associated cardiovascular risk factors in the community.

The prevalence of microalbuminuria and relationship to cardiovascular risk factors was examined in a cross-sectional community survey of cardiovascular risk factors. Microalbuminuria (when classified as albumin concentration greater than 20 micrograms/ml) was present in 6.3% of subjects but in conjunction with an albumin/creatinine ratio greater than 3.5 in only 2.2%. Diastolic blood pressure, prevalence of abnormal electrocardiographs, and to a lesser extent systolic blood pressure and fibrinogen concentration, were greater in those with albuminuria concentrations greater than 20 micrograms/ml. The strongest positive univariate correlates of albumin/creatinine ratios in those with detectable albuminuria were age, fibrinogen, blood pressure, total- and low density lipoprotein-(LDL) cholesterol, apo B and alcohol intake, whereas fasting insulin and insulin resistance were inversely correlated. Multiple regression analysis revealed that age, gender, systolic blood pressure and insulin resistance independently accounted for 37% of the variability in albumin/creatinine ratios. When those 10 subjects with microalbuminuria and albumin/creatinine ratios greater than 3.5 were matched with 20 with normoalbuminuria for age, gender and body mass index, the microalbuminuric subjects had significantly lower LDL cholesterol/apo B ratios and a tendency to lower high density lipoprotein (HDL) cholesterol and HDL cholesterol/apo A1 ratios. Microalbuminuria is uncommon in the general population, and is related to ageing, blood pressure and other vascular risk factors. It may reflect the presence of established cardiovascular disease.

Apolipoprotein E polymorphism and lipoproteins in insulin-treated diabetes mellitus.

Apolipoprotein E (apo E), a component of VLDL, HDL and chylomicron remnants, is inherited at a single genetic locus with 3 common alleles (epsilon 2, epsilon 3 and epsilon 4). epsilon 2 homozygosity is found in 0-2% of healthy populations, but in 75-100% of subjects with type III hyperlipoproteinaemia, in whom an increased prevalence of glucose intolerance has previously been reported. The lipoprotein abnormality associated with diabetes mellitus has features in common with type III hyperlipoproteinaemia and both conditions lead to accelerated atherogenesis with a similar anatomical distribution. We have therefore examined the frequency of apo E genotypes in 120 subjects with insulin-treated diabetes mellitus (ITDM) and 107 healthy controls, and examined the effect of apo E polymorphism on lipoproteins in the diabetic group. As in the general population, the apo E phenotype in ITDM was a significant determinant of the total serum and LDL cholesterol concentrations which were lowest in patients possessing the epsilon 2 allele, intermediate in those homozygous for epsilon 3 and highest in those with an epsilon 4 allele. The observed gene frequencies of epsilon 2 (0.091), epsilon 3 (0.780) and epsilon 4 (0.130) were similar to those of the healthy control group and those in the general population. However, there was an unexpected increase (P less than 0.0002) in epsilon 2 homozygosity of 6.7% compared to a prevalence of 0.8% predicted both from the Hardy-Weinberg equilibrium and the 0.9% prevalence observed in the healthy control group. This suggests either that epsilon 2 homozygosity increases susceptibility to the development of ITDM or that the two conditions are genetically linked.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet function and survival in rats with genetically determined hypercholesterolaemia.

Platelets from rats with genetically determined hypercholesterolaemia are hypersensitive to aggregation induced by thrombin compared with platelets from their genetic controls without hypercholesterolaemia. Aggregation or release induced by thrombin of platelets from hypercholesterolaemic and control rats correlated significantly with plasma cholesterol concentrations. Platelet responses to ADP or collagen were not different between the groups. The hypersensitivity to thrombin-induced aggregation was independent of released ADP or products of arachidonic acid metabolism. The changes in platelet sensitivity occurred with only moderate increases in plasma cholesterol concentration and with no detectable changes in total platelet cholesterol. The hypersensitivity of platelets from hypercholesterolaemic rats was not associated with a reduction in platelet survival or any significant injury to the aortic endothelium in these animals. Platelets from hypercholesterolaemic rats were smaller than platelets from controls. Thus, platelets from rats with genetically determined hypercholesterolaemia have alterations in function similar to those found with platelets from rats with diet-induced hypercholesterolaemia indicating that this strain can be used to study the mechanisms by which cholesterol can change platelet function without the possible complicating effects of dietary factors. Since platelet hypersensitivity occurred in rats with genetically determined hypercholesterolaemia without a reduction in platelet survival, these studies are also consistent with the reduced platelet survival found in animals with diet-induced hypercholesterolaemia being independent of platelet changes.