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Biomedical subjects

D M Nathan

Publications and source records attributed to D M Nathan.

At least 19 recordsLinked to original sources
PubMed2004

Clinical inertia in the management of Type 2 diabetes metabolic risk factors.

AIMS: Delays in the initiation and intensification of medical therapy may be one reason patients with diabetes do not reach evidence-based goals for metabolic control. We assessed intensification of medical therapy over time, comparing the management of hyperglycaemia, hypertension, and hyperlipidaemia. METHODS: Prospective cohort study of 598 adults with Type 2 diabetes receiving primary care in an academic medical centre from May 1997 to April 1999. We assessed whether patients failing to achieve standard treatment goals for haemoglobin A1c (HbA1c), systolic blood pressure (SBP), or low density lipoprotein (LDL) cholesterol when last measured during 12 months (Year 1, 5/97-4/98) had increases in their corresponding medical regimen during the following 12 months (Year 2, 5/98-4/99). RESULTS: Among untreated patients in Year 1, seven of 12 (58%) of those above goal for HbA1c were initiated on medical therapy in Year 2, compared with 16 of 48 (34%) above SBP goal (P=0.02) and 26 of 115 (23%) above LDL cholesterol goal (P=0.02). Among patients on therapy and above goal, 124 of 244 (51%) patients with elevated HbA1c had their regimen increased in Year 2, compared with 85 of 282 (30%) with elevated SBP (P<0.001) and 22 of 79 (30%) with elevated LDL cholesterol (P<0.001). From Year 1 to Year 2 there was a decline in the overall proportion of patients above goal for LDL cholesterol (from 58% to 45%, P=0.002) but not for HbA1c or blood pressure. CONCLUSIONS: Greater initiation and intensification of pharmaceutical therapy, particularly for elevated blood pressure or cholesterol, may represent a specific opportunity to improve metabolic control in Type 2 diabetes.

Aged↗
PubMed2001

The impact of diabetes mellitus on mortality from all causes and coronary heart disease in women: 20 years of follow-up.

BACKGROUND: Few data are available on the long-term impact of type 2 diabetes mellitus on total mortality and fatal coronary heart disease (CHD) in women. METHODS: We examined prospectively the impact of type 2 diabetes and history of prior CHD on mortality from all causes and CHD among 121 046 women aged 30 to 55 years with type 2 diabetes in the Nurses' Health Study who were followed up for 20 years from 1976 to 1996. RESULTS: During 20 years of follow-up, we documented 8464 deaths from all causes, including 1239 fatal CHD events. Compared with women with no diabetes or CHD at baseline, age-adjusted relative risks (RRs) of overall mortality were 3.39 (95% confidence interval [CI], 3.08-3.73) for women with a history of diabetes and no CHD at baseline, 3.00 (95% CI, 2.50-3.60) for women with a history of CHD and no diabetes at baseline, and 6.84 (95% CI, 4.71-9.95) for women with both conditions at baseline. The corresponding age-adjusted RRs of fatal CHD across these 4 groups were 1.0, 8.70, 10.6, and 25.8, respectively. Multivariate adjustment for body mass index and other coronary risk factors only modestly attenuated the RRs. Compared with nondiabetic persons, the multivariate RRs of fatal CHD across categories of diabetes duration (< or =5, 6-10, 11-15, 16-25, >25 years) were 2.75, 3.63, 5.51, 6.38, and 11.9 (P< .001 for trend), respectively. The combination of prior CHD and a long duration of clinical diabetes (ie, >15 years) was associated with a 30-fold (95% CI, 20.7-43.5) increased risk of fatal CHD. CONCLUSIONS: Our data indicate that among women, history of diabetes is associated with dramatically increased risks of death from all causes and fatal CHD. The combination of diabetes and prior CHD identifies particularly high-risk women.

Adult↗
PubMed2001

Clinical and cost outcomes of medical nutrition therapy for hypercholesterolemia: a controlled trial.

OBJECTIVE: To compare the results and cost-effectiveness of a cholesterol lowering protocol implemented by registered dietitians with cholesterol lowering advice by physicians. DESIGN: Six month randomized controlled trial, cost-effectiveness analysis. Subjects included 90 ambulatory care patients (60 men, 30 women), age range 21 to 65 years, with hypercholesterolemia and not taking hypolipidemic drugs. Patients were randomly assigned to receive medical nutrition therapy (MNT) from dietitians using a NCEP based lowering protocol or usual care (UC) from physicians. Outcome measures were plasma lipid profiles, dietary intake, weight, activity, patient satisfaction, and costs of MNT. Changes from baseline for each variable of interest were compared between treatment groups using analysis of covariance controlling for baseline value of the variable and gender. RESULTS: MNT achieved a 6% decrease in total and LDL cholesterol levels at 3 and 6 months compared with a 1% increase and a 2% decrease in both values at 3 and 6 months with UC (P<.001 and P<.05, respectively). Weight loss (1.9 vs 0 kg, P<.001) and dietary intake of saturated fat (7% of energy vs 10%, P<.001) were better in the MNT than the UC group. The additional costs of MNT were $217 per patient to achieve a 6% reduction in cholesterol and $98 per patient to sustain the reduction. The cost-effectiveness ratio for MNT was $36 per 1% decrease in cholesterol and LDL level. APPLICATIONS/CONCLUSIONS: MNT from registered dietitians is a reasonable investment of resources because it results in significantly better lipid, diet, activity, weight, and patient satisfaction outcomes than UC.

Adult↗
PubMed2001

Sample exchange to compare insulin measurements between the San Antonio Heart Study and the Framingham Offspring Study.

Lack of assay standardization has precluded cross-study comparison of insulin levels. We exchanged blood samples between the San Antonio Heart and Framingham Offspring Studies to compare insulin measurements. Two randomly selected specimens were chosen for each non-diabetic man and woman in each of the bottom four quintiles and top two deciles of the originally assayed fasting and 2-hour post-challenge insulin distributions: 48 plasma samples from Framingham, and after further stratification by ethnicity, 96 serum samples from San Antonio. Total immunoreactive insulin was originally measured in both studies; we repeated the identical assay on exchanged samples. Repeat assays were performed a mean (SD) of 7.0 (0.8) years after collection in the Framingham study and 4.6 (1.1) years in the San Antonio study. Repeat insulin levels were highly correlated with original levels for both San Antonio samples repeated in Framingham (Pearson r=0.923) and for Framingham samples repeated in San Antonio (r=0.959). Original and repeat San Antonio serum insulin levels were similar (mean fasting and 2-hour combined original level 154 pmol/l vs. 142 pmol/l on repeat in Framingham). Framingham plasma insulin levels repeated in San Antonio were substantially lower than original levels (120 pmol/l vs. 336 pmol/l), as were an additional 12 samples repeat assayed in Framingham (93 pmol/l vs. 320 pmol/l). Repeat rank ordering in both studies was excellent: over 90% of subjects originally classified as hyperinsulinemic (top tertile of the combined distribution) were again classified as hyperinsulinemic upon repeat assay. We conclude that sample exchange for insulin measurement is simple and feasible. Original and repeat insulin levels are highly correlated; subjects originally classified as hyperinsulinemic remain so classified upon repeat assay. Associated regression curves can be used to calibrate insulin levels to a common reference standard, allowing epidemiology studies to compare levels of insulin and associated risk factors.

Blood Chemical Analysis↗
PubMed2001

Fasting plasma homocysteine levels in the insulin resistance syndrome: the Framingham offspring study.

OBJECTIVE: Insulin resistance, associated metabolic abnormalities, and elevated homocysteine levels are risk factors for cardiovascular disease (CVD). We examined relationships between homocysteine levels and features of insulin resistance syndrome (IRS). RESEARCH DESIGN AND METHODS: We measured clinical characteristics, plasma levels of fasting homocysteine, folate, B vitamins, creatinine, and fasting and 2-h insulin and glucose levels after a 75-g oral glucose tolerance test in 2,214 subjects without CVD at the fifth examination (1991-1995) of the Framingham Offspring Study. After excluding 203 subjects with diabetes, the remaining 2,011 subjects were categorized as having none, one, two, or all three of the phenotypes of IRS: impaired glucose tolerance, hypertension, and/or a central metabolic syndrome (two or more traits: obesity, dyslipidemia, or hyperinsulinemia). In addition, in 1,592 subjects attending the sixth examination (1995-1998), we measured the urine albumin/creatinine ratio (UACR). Age-, sex-, creatinine-, vitamin-, and UACR-adjusted mean homocysteine levels or proportions with homocysteine >14 micromol/l in each phenotypic category and differences between categories were assessed with regression models. RESULTS: The mean age of the subjects was 54 years (range 28-82); 55% were women, 12.3% had hyperinsulinemia, and 15.9% had two or more of the IRS phenotypes. Adjusted mean homocysteine levels were higher comparing those with hyperinsulinemia (9.8 micromol/l) and those without (9.4 micromol/l, P = 0.04) and were higher among subjects with two or more IRS phenotypes (9.9 micromol/l) compared with those with 1 or no phenotype (9.3 micromol/l, P = 0.003). Mean UACR levels were also higher among subjects with two or more IRS phenotypes (7.2 mg/g) compared with those with 1 or no phenotype (5.5 mg/g, P = 0.007). CONCLUSIONS: Hyperhomocysteinemia and abnormal urinary albumin excretion are both associated with hyperinsulinemia and may partially account for increased risk of CVD associated with insulin resistance. Because hyperhomocysteinemia and microalbuminuria also reflect endothelial injury, these observations also support the hypothesis that endothelial dysfunction is associated with expression of the IRS.

Adult↗
PubMed2000

Hyperinsulinemia, hyperglycemia, and impaired hemostasis: the Framingham Offspring Study.

CONTEXT: Increased risk for cardiovascular disease in persons with glucose intolerance (impaired glucose tolerance and type 2 diabetes mellitus) is not fully explained by concomitant elevations in traditional atherosclerosis risk factors. Hyperinsulinemia associated with glucose intolerance may increase risk directly, or its effect could be mediated through impaired hemostatic function. OBJECTIVE: To evaluate associations between fasting insulin levels and hemostatic factors in subjects with normal and impaired glucose homeostasis. DESIGN: Cross-sectional analysis conducted between January 1991 and June 1995. SETTING: The population-based Framingham Offspring Study. SUBJECTS: A total of 1331 men and 1631 women aged 26 to 82 years, without diagnosed diabetes or cardiovascular disease and classified as having normal glucose tolerance (80.2%) or glucose intolerance (impaired glucose tolerance and impaired fasting glucose combined, 15.2%; previously undiagnosed diabetes, 4.7%) using an oral glucose tolerance test. MAIN OUTCOME MEASURES: Trends across quintiles of fasting insulin in levels of plasminogen activator inhibitor 1 (PAI-1) antigen, tissue-type plasminogen activator (tPA) antigen, von Willebrand factor (vWF) antigen, factor VII antigen, fibrinogen, and plasma viscosity. We stratified analyses by sex and glucose tolerance status and adjusted hemostatic factor levels for obesity, lipid levels, and traditional cardiovascular disease risk factors. RESULTS: Mean levels of all hemostatic factors (except for fibrinogen in men) increased across fasting insulin quintiles among subjects with normal glucose tolerance (P<.001 for trend). Levels of PAI-1 and tPA antigens, but not other hemostatic factors, were higher comparing subjects with glucose intolerance with those with normal glucose tolerance (P<.001). Among subjects with glucose intolerance, levels of PAI-1 and tPA antigen in men and women (P<.01 for trend) and vWF antigen in men (P<.05 for trend) increased significantly across insulin quintiles, but levels of factor VII antigen, fibrinogen, and plasma viscosity did not increase. CONCLUSIONS: Elevated levels of fasting insulin are associated with impaired fibrinolysis and hypercoagulability in subjects with normal glucose tolerance. Hyperinsulinemia is associated primarily with impaired fibrinolysis in subjects with glucose intolerance. Excess risk for cardiovascular disease associated with hyperinsulinemia and glucose intolerance may be mediated in part by enhanced potential for acute thrombosis.

Adult↗
PubMed2000

A prospective study of cigarette smoking and the incidence of diabetes mellitus among US male physicians.

PURPOSE: To determine the association between cigarette smoking and the incidence of type 2 diabetes mellitus. SUBJECTS AND METHODS: We studied 21,068 US male physicians aged 40 to 84 years in the Physicians' Health Study who were initially free of diagnosed diabetes mellitus, cardiovascular disease, and cancer. Information about cigarette smoking and other risk indicators was obtained at baseline. The primary outcome was reported diagnosis of type 2 diabetes mellitus. RESULTS: During 255,830 person-years of follow-up, 770 new cases of type 2 diabetes mellitus were identified. Smokers had a dose-dependent increased risk of developing type 2 diabetes mellitus: compared with never smokers, the age-adjusted relative risk was 2.1 (95% confidence interval [CI]: 1.7 to 2.6) for current smokers of > or = 20 cigarettes per day, 1.4 (95% CI: 1.0 to 2.0) for current smokers of <20 cigarettes per day, and 1.2 (95% CI: 1.0 to 1.4) for past smokers. After multivariate adjustment for body mass index, physical activity, and other risk factors, the relative risks were 1.7 (95% CI: 1.3 to 2.3) for current smokers of > or = 20 cigarettes per day, 1.5 (95% CI: 1.0 to 2.2) for current smokers of <20 cigarettes per day, and 1.1 (95% CI: 1.0 to 1.4) for past smokers. Total pack-years of cigarette smoking was also associated with the risk of type 2 diabetes mellitus (P for trend <0.001). CONCLUSIONS: These prospective data support the hypothesis that cigarette smoking is an independent and modifiable determinant of type 2 diabetes mellitus.

Adult↗
PubMed2000

Apolipoprotein E isoform polymorphisms are not associated with insulin resistance: the Framingham Offspring Study.

OBJECTIVE: Insulin resistance and the apolipoprotein (apo) allele e4 have both been associated with coronary heart disease (CHD). We examined the relationship between insulin resistance and apo(e) polymorphisms among participants in the Framingham Offspring Study. RESEARCH DESIGN AND METHODS: During 1991-1995, subjects underwent a clinical examination and an oral glucose tolerance test with measurement of fasting and 2-h glucose, insulin levels, and fasting lipid levels. We measured insulin resistance using the homeostasis model, in which insulin resistance (HOMA-IR) = fasting insulin x glucose/22.5. Apo(e) isoforms and phenotypes were determined in 1983-1987 using isoelectric focusing of plasma VLDL. Of the 2,120 subjects with complete HOMA-IR and apo(e) data, 204 with type 2 diabetes were excluded. The remainder were classified with features of the insulin resistance syndrome including impaired glucose tolerance (1997 American Diabetes Association criteria), hypertension (criteria from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure [6th report]), obesity (BMI >85th percentile), high waist-to-hip ratio (>85th percentile), and high triglyceride and low HDL levels (NCEP-2 criteria). We analyzed data with contingency tables and age- and sex-adjusted logistic regression models. RESULTS: Among the 1,916 subjects, the mean age was 55 (range 28-83 years) and 51% were women. Median HOMA-IR was 6.4 (interquartile range 5.2-8.2), and allele frequencies were 7.8, 79.9, and 12.4% for apo(e) alleles e2, e3, and e4, respectively There were no differences in proportions of apo(e) isoforms or alleles across increasing quintiles of HOMA-IR. A less dramatic increase in proportions occurred with elevated triglycerides associated with increasing HOMA-IR among those with apo(e) isoforms 2/2 and 2/3 compared with the others (P < or = 0.01 for interaction). Otherwise, apo(e) did not substantially modify associations between insulin resistance and features of the insulin resistance syndrome. CONCLUSIONS: There is no association between apo(e) polymorphisms and insulin resistance. These appear to represent 2 completely independent risk factors for CHD.

Adult↗
PubMed1999

Determinants of retinopathy progression in type 1 diabetes mellitus.

PURPOSE: To determine the risk factors for retinopathy progression in type 1 (insulin-dependent) diabetes mellitus in a prospective cohort study. SUBJECTS AND METHODS: Subjects were 485 participants in the Sorbinil Retinopathy Trial, a randomized trial of aldose reductase inhibition among patients aged 18 to 56 years with type 1 diabetes mellitus (duration of 1 to 15 years) and no or only mild retinopathy. Retinopathy progression, assessed by seven-field stereoscopic fundus photography, was defined as worsening by two or more levels on a standardized grading scale at the end of follow-up (median, 41 months). RESULTS: The relative risks for retinopathy progression according to successively greater quintiles of total glycosylated hemoglobin level at baseline, after adjusting for age, diabetes duration, sorbinil assignment, and other variables, were 1.0, 2.0, 1.6, 3.7, and 4.4 (P trend <0.0001). Risk increased with greater baseline diastolic blood pressure: 1.0 for <70 mm Hg, 1.2 for 70 to 79 mm Hg, and 1.8 for > or =80 mm Hg (P for trend = 0.04). Diastolic blood pressure was a significant risk factor for progression in participants with mild baseline retinopathy (P for trend <0.02) but not in those without retinopathy at entry. Systolic blood pressure, by comparison, was not associated with progression. Baseline total cholesterol level was a marginally significant predictor of retinopathy progression when examined as a categorical variable (relative risks for increasing quartiles; 1.0, 1.6, 1.8, 1.9; P for trend = 0.03) but not when it was examined as a continuous variable or when hypercholesterolemic patients were compared with those with normal levels. Furthermore, when cholesterol levels were updated in subsequent visits, it was not a significant predictor of progression, and low density lipoprotein (LDL) cholesterol levels did not predict progression no matter how analyzed. Smoking was not associated with progression of retinopathy. CONCLUSIONS: Levels of hyperglycemia and diastolic blood pressure predicted progression of retinopathy in type 1 diabetes mellitus. We found only a suggestion of an association between total cholesterol level (but not of LDL cholesterol level) and progression of retinopathy; resolution of this issue will require additional studies with larger sample sizes and longer follow-up.

Adult↗
PubMed1999

Immediate feedback of HbA1c levels improves glycemic control in type 1 and insulin-treated type 2 diabetic patients.

OBJECTIVE: Accurate and reliable HbA1c results can be obtained at the time of the office visit by using benchtop analyzers. We tested the hypothesis that immediately available HbA1c results could improve glycemic control by changing physician or patient behavior or both. RESEARCH DESIGN AND METHODS: A randomized controlled trial was conducted in 201 type 1 and insulin-treated type 2 diabetic patients attending an academic diabetes center. HbA1c levels, changes in insulin therapy, and use of health care resources were assessed during a 12-month follow-up period. RESULTS: HbA1c levels decreased significantly at 6 and 12 months in the immediate assay group (-0.57 +/- 1.44 and -0.40 +/- 1.65%, respectively; P < 0.01) but did not change in the control group (-0.11 +/- 0.79 and -0.19 +/- 1.16%, respectively; NS). The changes were similar for both type 1 and type 2 diabetic patients. There were no differences in the rates of hypoglycemic events or use of health care resources. CONCLUSIONS: In the setting of a controlled randomized trial, the immediate feedback of HbA1c results at the time of patient encounters resulted in a significant improvement of glycemic control at 6-month follow-up and persisted for the 12-month study. The introduction of this assay was positively received by both patients and physicians.

Blood Glucose↗
PubMed1998

Metabolic risk factors worsen continuously across the spectrum of nondiabetic glucose tolerance. The Framingham Offspring Study.

BACKGROUND: Categorical definitions for glucose intolerance imply that risk thresholds exist, but metabolic risk for type 2 diabetes mellitus or cardiovascular disease may increase continuously as glucose intolerance increases. OBJECTIVE: To examine the distributions of the following metabolic risk factors across the spectrum of glucose tolerance: overall and central obesity, hypertension, low levels of high-density lipoprotein cholesterol, and increased triglyceride and insulin levels. DESIGN: Cross-sectional analysis. SETTING: The community-based Framingham Offspring Study. PARTICIPANTS: 2583 adults without previously diagnosed diabetes. MEASUREMENTS: Clinical data; fasting glucose, insulin, and lipid levels; and glucose and insulin levels taken 2 hours after oral challenge were collected from 1991 to 1993. Glucose tolerance was determined by 1980 World Health Organization criteria. Patients with normal glucose tolerance were categorized into quintiles of fasting glucose. The distributions of each metabolic risk factor and the metabolic sum of the six risk factors were assessed across seven categories from the lowest quintile of normal fasting glucose level through impaired glucose tolerance and previously undiagnosed diabetes. RESULTS: The mean age of patients was 54 years (range, 26 to 82 years); 52.7% of patients were women. Glucose tolerance testing found that 12.7% of patients had impaired glucose tolerance and 4.8% had previously undiagnosed diabetes. Multivariable-adjusted mean measures of risk factors and odds ratios for obesity, elevated waist-to-hip ratio, hypertension, low levels of high-density lipoprotein cholesterol, elevated triglyceride levels, and hyperinsulinemia showed continuous increases across the spectrum of nondiabetic glucose tolerance. Although a threshold effect near the upper range of nondiabetic glucose tolerance could not be ruled out for triglyceride levels in men and for insulin levels 2 hours after oral challenge in men and women, no other metabolic risk factors showed clear evidence of thresholds for increased risk. CONCLUSIONS: Metabolic risk factors for type 2 diabetes mellitus and for cardiovascular disease worsen continuously across the spectrum of glucose tolerance categories, beginning in the lowest quintiles of normal fasting glucose level.

Adult↗
PubMed1997

Metabolic control and prevalent cardiovascular disease in non-insulin-dependent diabetes mellitus (NIDDM): The NIDDM Patient Outcome Research Team.

PURPOSE: Cardiovascular disease is a major cause of morbidity and death in non-insulin-dependent diabetes mellitus (NIDDM). While hyperglycemia is clearly related to diabetic microvascular complications, it contribution to large-vessel atherosclerosis is controversial. PATIENTS AND METHODS: We performed an analysis of the association between glycemic control and prevalent cardiovascular disease in 1,539 participants in the NIDDM Patient Outcomes Research Team study who were under usual care in a health maintenance organization. Prevalent cardiovascular disease and its risk factors were identified by self-administered questionnaire. Cardiovascular disease was defined by the presence of coronary heart disease, peripheral vascular disease, and/or cerebrovascular disease. Glycohemoglobin and lipid levels were obtained from a computerized laboratory database. RESULTS: The mean age of participants was 63 years (range 31 to 91); 51% were women. The mean duration of NIDDM was 9 years (range < 1 to 50), 35% took insulin, and 48% took sulfonylureas. Mean glycohemoglobin was 10.6%. Sixty percent had hypertension, 16% currently smoked cigarettes, and the mean total high-density lipoprotein (HDL) cholesterol ratio was 5.7. Fifty-one percent had cardiovascular disease. Cardiovascular disease prevalence remained constant across increasing quartiles of glycohemoglobin for both men and women. In contrast, prevalent cardiovascular disease was associated with established cardiovascular disease risk factors including age (67 versus 59 years, P < 0.0001), hypertension (66% versus 54%, P < 0.0001), current cigarette smoking (17% versus 13%, P < 0.005), and total/HDL cholesterol ratio (5.9 versus 5.6, P < 0.005). Cardiovascular disease was also associated with duration of NIDDM (11 versus 8 years, P < 0.0001). In multiple logistic regression analysis controlling for established cardiovascular disease risk factors and diabetes duration and therapy, glycohemoglobin remained unassociated with cardiovascular disease. CONCLUSIONS: Glycemic control is not associated with prevalent cardiovascular disease in this large population of individuals with NIDDM. Conventional cardiovascular disease risk factors are independently associated with cardiovascular disease and be a more promising focus for clinical intervention to reduce atherosclerotic complications in NIDDM.

Adult↗