Incident Dysglycemia and Progression to Type 1 Diabetes Among Participants in the Diabetes Prevention Trial�CType 1

OBJECTIVE

We studied the incidence of dysglycemia and its prediction of the development of type 1 diabetes in islet cell autoantibody (ICA)-positive individuals. In addition, we assessed whether dysglycemia was sustained.

RESEARCH DESIGN AND METHODS

Participants (n = 515) in the Diabetes Prevention Trial–Type 1 (DPT-1) with normal glucose tolerance who underwent periodic oral glucose tolerance tests (OGTTs) were followed for incident dysglycemia (impaired fasting glucose, impaired glucose tolerance, and/or high glucose levels at intermediate time points of OGTTs). Incident dysglycemia at the 6-month visit was assessed for type 1 diabetes prediction.

RESULTS

Of 515 participants with a normal baseline OGTT, 310 (60%) had at least one episode of dysglycemia over a maximum follow-up of 7 years. Dysglycemia at the 6-month visit was highly predictive of the development of type 1 diabetes, both in those aged <13 years (P < 0.001) and those aged ≥13 years (P < 0.01). Those aged <13 years with dysglycemia at the 6-month visit had a high cumulative incidence (94% estimate by 5 years). Among those who developed type 1 diabetes after a dysglycemic OGTT and who had at least two OGTTs after the dysglycemic OGTT, 33 of 64 (52%) reverted back to a normal OGTT. However, 26 (79%) of the 33 then had another dysglycemic OGTT before diagnosis.

CONCLUSIONS

ICA-positive individuals with normal glucose tolerance had a high incidence of dysglycemia. Incident dysglycemia in those who are ICA positive is strongly predictive of type 1 diabetes. Children with incident dysglycemia have an especially high risk. Fluctuations in and out of the dysglycemic state are not uncommon before the onset of type 1 diabetes.There is increasing evidence that impaired glucose tolerance (IGT) is a predictor and common precursor of type 1 diabetes (1–3). Still, little is known about the incidence of IGT and other forms of dysglycemia in individuals who have pancreatic autoantibodies and normal glucose tolerance. In addition, there is no information about the risk of type 1 diabetes when dysglycemia occurs in those individuals. Moreover, it is not known whether dysglycemia is sustained once it occurs.We used data from the Diabetes Prevention Trial–Type 1 (DPT-1) (4,5) to examine these questions. In addition to IGT, impaired fasting glucose (IFG) and high glucose values at intermediate times (between fasting and 2 h) during oral glucose tolerance tests (OGTTs), termed indeterminate glycemia (INDET), were included as other forms of dysglycemia in the analyses. Glucose levels at intermediate times have been shown to be predictive of type 1 diabetes (6,7).Information regarding the incidence of these various forms of dysglycemia and their prediction of type 1 diabetes should be helpful for understanding the pathogenesis and natural history of type 1 diabetes. Such information should also be useful for improving type 1 diabetes prevention trials.     

Is There a Link Between Components of Health-Related Functioning and Incident Impaired Glucose Metabolism and Type 2 Diabetes?: The Australian Diabetes Obesity and Lifestyle (AusDiab) study

OBJECTIVE

To determine the longitudinal association of components of health-related functioning (HRF) with incident impaired glucose metabolism and type 2 diabetes.

RESEARCH DESIGN AND METHODS

The Australian Diabetes Obesity and Lifestyle (AusDiab) study is a national, longitudinal study of adults aged ≥25 years from 42 randomly selected areas of Australia. Diabetes status was defined using the World Health Organization criteria, and HRF was assessed using the SF-36 questionnaire in 1999–2000 and 2004–2005.

RESULTS

Incident impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and newly diagnosed type 2 diabetes were associated with increased bodily pain at baseline compared with those with normal glucose tolerance (NGT) (IFG P = 0.005, IGT P < 0.004, and newly diagnosed type 2 diabetes P = 0.005), after adjustment. In addition, those with incident IGT and newly diagnosed type 2 diabetes had significantly reduced physical functioning, general health, mental health, and vitality at baseline compared with those with NGT. After we controlled for factors associated with incident diabetes, those in the lowest quartile of the physical component summary scale at baseline had at least a 50% higher risk of progression to impaired glucose metabolism and diabetes 5 years later.

CONCLUSIONS

These findings show that incident IFG, IGT, and newly diagnosed type 2 diabetes are associated with reduced HRF independent of cardiovascular disease and that this is evident before the onset of these conditions. If future health promotion campaigns are to effectively target those at high risk of developing diabetes, an understanding of the process of declining health before onset of the disease is essential.The prevalence of type 2 diabetes is increasing rapidly throughout the world. The difficulties in curbing this trend make it vital that we fully understand all aspects of the disease process. Although traditional risk factors for type 2 diabetes have been extensively studied, the role of components of health-related functioning (HRF), an important component of health (1), has not fully been explored in contemporary, population-based studies.There is now growing evidence to suggest that HRF, which reflects a measure of physical, social, and mental health functioning, may be impaired before the onset of type 2 diabetes (2). A small number of cross-sectional studies have suggested that those with impaired fasting glucose (IFG) and or impaired glucose tolerance (IGT) have reduced HRF compared with those with normal glucose tolerance (NGT) on a number of the SF-36 dimensions (3–5). Although many studies have previously shown that individuals with diabetes-related complications have reduced HRF compared with those without complications (6,7) and several studies have shown that HRF is impaired among those with diabetes compared with those without diabetes (8,9), little is known about the stage of the disease at which HRF becomes impaired. This is important to establish if a holistic approach to health care is to be taken, and we are to fully understand the etiology and pathogenesis of the disease.An understanding of how some psychosocial factors directly impact the development of type 2 diabetes and other chronic diseases is already beginning to emerge. Psychosocial stress, for example, is known to increase the inflammatory process (10,11) and has been linked directly with accelerated atherosclerosis (10), myocardial ischemia (12), and incident type 2 diabetes (2). This finding suggests that psychosocial risk factors are likely to be important to consider in the identification of individuals at high risk of developing type 2 diabetes, as well as in interventions to prevent diabetes. The Australian Diabetes, Obesity and Lifestyle (AusDiab) study, with its large, national, population-based sample, with 5 years of follow-up, provides an ideal setting in which to investigate the association of HRF with the subsequent development of impaired glucose metabolism and type 2 diabetes.     

Influence of Type 2 Diabetes on Brain Volumes and Changes in Brain Volumes: Results from the Women’s Health Initiative Magnetic Resonance Imaging Studies

OBJECTIVE

To study how type 2 diabetes adversely affects brain volumes, changes in volume, and cognitive function.

RESEARCH DESIGN AND METHODS

Regional brain volumes and ischemic lesion volumes in 1,366 women, aged 72–89 years, were measured with structural brain magnetic resonance imaging (MRI). Repeat scans were collected an average of 4.7 years later in 698 women. Cross-sectional differences and changes with time between women with and without diabetes were compared. Relationships that cognitive function test scores had with these measures and diabetes were examined.

RESULTS

The 145 women with diabetes (10.6%) at the first MRI had smaller total brain volumes (0.6% less; P = 0.05) and smaller gray matter volumes (1.5% less; P = 0.01) but not white matter volumes, both overall and within major lobes. They also had larger ischemic lesion volumes (21.8% greater; P = 0.02), both overall and in gray matter (27.5% greater; P = 0.06), in white matter (18.8% greater; P = 0.02), and across major lobes. Overall, women with diabetes had slightly (nonsignificant) greater loss of total brain volumes (3.02 cc; P = 0.11) and significant increases in total ischemic lesion volumes (9.7% more; P = 0.05) with time relative to those without diabetes. Diabetes was associated with lower scores in global cognitive function and its subdomains. These relative deficits were only partially accounted for by brain volumes and risk factors for cognitive deficits.

CONCLUSIONS

Diabetes is associated with smaller brain volumes in gray but not white matter and increasing ischemic lesion volumes throughout the brain. These markers are associated with but do not fully account for diabetes-related deficits in cognitive function.Many interrelated factors adversely affect the brain health of individuals with type 2 diabetes, including energy dysregulation, inflammation, reduced perfusion, and increased oxidative stress and protein deposition (1,2). In cross-sectional studies, type 2 diabetes is often associated with smaller brain volumes and, less consistently, with greater amounts of white matter hyperintensities and other markers of cerebrovascular disease (3,4). Two longitudinal magnetic resonance imaging (MRI) studies have documented increased rates of total brain atrophy, which appeared to be greater among individuals with lower cognitive function, but not increased accumulations of white matter hyperintensities (5,6). The relative increases in atrophy associated with diabetes remained after covariate adjustment for many risk factors for cognitive dysfunction, including age, blood pressures, education, lipid levels, and BMI.This article is organized with three aims. In a large cohort of older women, we first describe the cross-sectional associations that diabetes had with brain tissue volumes and ischemic lesion loads. We do so for the whole brain and separately for white matter, gray matter, and major lobes. Second, among the women assessed longitudinally with MRI, we examine whether changes in brain tissue and ischemic lesion volumes varied according to diabetes status. Finally, we examine associations that brain volumes and ischemic lesion volumes had with global cognitive function and its subdomains and examine the degree to which they account for diabetes-related relative deficits. There has been one report that diabetes is associated with greater adverse effects on changes in brain structure among women than men (5), perhaps because diabetes often co-occurs with relatively more vascular risk factors among women with versus without diabetes than is the case among men (7). We analyze data from the first sufficiently large cohort of women to characterize the extent to which diabetes-related brain changes account for relative cognitive deficits.     

Is the Recent Rise in Type 2 Diabetes Incidence From 1984 to 2007 Explained by the Trend in Increasing BMI?: Evidence from a prospective study of British men

OBJECTIVE

To estimate the extent to which increasing BMI may explain the rise in type 2 diabetes incidence in British men from 1984 to 2007.

RESEARCH DESIGN AND METHODS

A representative cohort ratio of 6,460 British men was followed-up for type 2 diabetes incidence between 1984 (aged 45–65 years) and 2007 (aged 67–89 years). BMI was ascertained at regular intervals before and during the follow-up.

RESULTS

Between 1984–1992 and 1999–2007, the age-adjusted hazard of type 2 diabetes more than doubled (hazard ratio 2.33 [95% CI 1.75–3.10]). Mean BMI rose by 1.42 kg/m² (95% CI 1.10–1.74) between 1984 and 1999; this could explain 26% (95% CI 17–38) of the type 2 diabetes increase.

CONCLUSIONS

An appreciable portion of the rise in type 2 diabetes can be attributed to BMI changes. A substantial portion remains unexplained, possibly associated with other determinants such as physical activity. This merits further research.In the U.K., incidence of type 2 diabetes has increased by two-thirds in the last decade (1), and in the U.S. incidence has doubled over the last 30 years (2). Understanding the reasons for these unfavourable trends will help inform efforts to curb future type 2 diabetes increases. Marked rises in population adiposity have also occurred (3–5). However, few attempts have been made to quantify the contribution of changes in adiposity to the observed time trend in type 2 diabetes, partly reflecting the paucity of studies that have simultaneously monitored both type 2 diabetes and BMI levels in the same population over an extended period. We have estimated the proportion of the time-trend in type 2 diabetes incidence in British men over 24 years that may be explained by increasing population adiposity levels.     

Evolution of Percutaneous Coronary Intervention in Patients with Diabetes: A report from the National Heart, Lung, and Blood Institute�Csponsored PTCA (1985�C1986) and Dynamic (1997�C2006) Registries

OBJECTIVE

To evaluate the association of successive percutaneous coronary intervention (PCI) modalities with balloon angioplasty (BA), bare-metal stent (BMS), drug-eluting stents (DES), and pharmacotherapy over the last 3 decades with outcomes among patients with diabetes in routine clinical practice.

RESEARCH DESIGN AND METHODS

We examined outcomes in 1,846 patients with diabetes undergoing de novo PCI in the multicenter, National Heart, Lung, and Blood Institute–sponsored 1985–1986 Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry and 1997–2006 Dynamic Registry. Multivariable Cox regression models were used to estimate the adjusted risk of events (death/myocardial infarction [MI], repeat revascularization) over 1 year.

RESULTS

Cumulative event rates for postdischarge (31–365 days) death/MI were 8% by BA, 7% by BMS, and 7% by DES use (P = 0.76) and for repeat revascularization were 19, 13, and 9% (P < 0.001), respectively. Multivariable analysis showed a significantly lower risk of repeat revascularization with DES use when compared with the use of BA (hazard ratio [HR] 0.41 [95% CI 0.29–0.58]) and BMS (HR 0.55 [95% CI 0.39–0.76]). After further adjustment for discharge medications, the lower risk for death/MI was not statistically significant for DES when compared with BA.

CONCLUSIONS

In patients with diabetes undergoing PCI, the use of DES is associated with a reduced need for repeat revascularization when compared with BA or BMS use. The associated death/MI benefit observed with the DES versus the BA group may well be due to greater use of pharmacotherapy.The practice of percutaneous coronary intervention (PCI) has evolved rapidly in the past 3 decades, with technological advancements from balloon angioplasty (BA) to bare-metal stents (BMS) and the more recent drug-eluting stents (DES) (1). Comparisons of device-specific outcomes have yielded similar results, with a recent meta-analysis reporting a significant reduction in the rate of target lesion revascularization, but not mortality, with DES use compared with BMS use (2).Coronary angioplasty in patients with diabetes has been shown to have a higher rate of infarction and a greater need for additional revascularization procedures (3). In a large consecutive series of patients treated by elective stent implantation, patients with diabetes were at higher risk for in-hospital mortality and subsequent revascularization, which ultimately resulted in a significantly lower cardiac event-free survival rate (4). Yet, the benefit of DES over BMS remains unclear. A pooled analysis (5) reported a significant difference in survival in favor of BMS over the DES, whereas no significant difference in mortality was observed in another analysis of 14 randomized controlled trials (6). Given these inconsistent findings and the growing percentage of diabetic patients undergoing PCI, the impact of advances in PCI technology and adjunct improvement in pharmacotherapy on outcomes in patients with diabetes needs to be assessed.We, therefore, investigated the effectiveness of PCI in patients with diabetes by comparing 1-year rates of death/myocardial infarction (MI) and repeat revascularization across the three device modalities: BA, BMS, and DES. Data from the multicenter, National Heart, Lung, and Blood Institute (NHLBI)-sponsored 1985–1986 Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry and the 1997–2006 Dynamic Registry were used for this purpose.     

Are the 2005 Dietary Guidelines for Americans Associated With Reduced Risk of Type 2 Diabetes and Cardiometabolic Risk Factors?: Twenty-year findings from the CARDIA study

OBJECTIVE

To examine the prospective association between accordance with the 2005 Dietary Guidelines for Americans (DGA) and subsequent diabetes incidence and changes in cardiometabolic risk factors.

RESEARCH DESIGN AND METHODS

The sample consisted of 4,381 black and white young adults examined repeatedly from 1985 to 2005. We used the 2005 Diet Quality Index (DQI) to rate participants’ diets based on meeting key dietary recommendations conveyed by the 2005 DGA.

RESULTS

Overall, we found no association between DQI score and diabetes risk using Cox models adjusted for potential confounders. Higher DQI scores were associated with favorable changes in HDL cholesterol and blood pressure overall (P for trend <0.05), but with increased insulin resistance among blacks (P for trend <0.01).

CONCLUSIONS

Our findings highlight the need for evaluation of the DGA’s effectiveness, particularly among ethnic minority populations. Clinicians should be aware that following the DGA might not lower diabetes risk.The Dietary Guidelines for Americans (DGA) are the basis for federal nutrition programs (1), yet there is little evidence that diets congruent with the guidelines are effective in preventing chronic disease and thus are relevant to clinical care. We examined the prospective association between a diet consistent with the key dietary recommendations of the 2005 DGA and 1) 20-year incidence of type 2 diabetes; and 2) 13-year changes in HDL cholesterol, insulin resistance, blood pressure, and triglycerides in a cohort of black and white Americans.     

Epidemiological Perspectives on Type 1 Diabetes in Childhood and Adolescence in Germany: 20 years of the Baden-W��rttemberg Diabetes Incidence Registry (DIARY)

OBJECTIVE

To predict the frequency of type 1 diabetes in childhood and adolescence (<15 years of age) in Germany for the next 20 years.

RESEARCH DESIGN AND METHODS

Data on diabetes onset has been collected by means of a registry in the federal German state of Baden-Württemberg (documentation period, 1987–2006; n = 5,108; completeness of data 98.1%).

RESULTS

The current incidence rate (2000–2006) is 19.4 per 100,000 per year (95% CI 18.6–20.2). The annual incidence rate can be expressed as a square of a linear function of the calendar year X [y = (3.05 + 0.0778 × {X–1986})²; r² = 0.90]. The highest increase per year was observed in the age-groups comprising 2- and 3-year-olds (12 and 13% per year, respectively). The incidence rate for the year 2026 is estimated to be 37.9 per 100,000 per year (95% CI 33.3–42.9).

CONCLUSIONS

The increase that we found in younger children is characteristic of a left shift toward an earlier age.We present the statistics over 20 years pertaining to the frequency of type 1 diabetes among children and adolescents in the third largest state of Germany, which we derived from the Baden-Württemberg incidence register. We developed a prediction model in order to predict the frequency of diabetes for the total group (0–14 years of age) for the next 20 years. These data are essential for health care planning. Additionally, they provide further insight into the epidemiology of the disease in our country over a 40-year period.     

Insulin Resistance, ��-Cell Dysfunction, and Conversion to Type 2 Diabetes in a Multiethnic Population: The Insulin Resistance Atherosclerosis Study

OBJECTIVE

Insulin resistance and β-cell function are major predictors of type 2 diabetes, but studies using direct methods of insulin resistance and secretion are few and relatively small. Furthermore, the strength of these associations has not been tested in different ethnic groups and various states of glucose tolerance, family history of diabetes, and obesity.

RESEARCH DESIGN AND METHODS

Predictors of incident diabetes were evaluated in Hispanic, non-Hispanic white, and African American participants in the Insulin Resistance Atherosclerosis Study (aged 40–69 years). In 557 participants with normal glucose tolerance and 269 with impaired glucose tolerance (IGT), insulin sensitivity (insulin sensitivity index [S^I]) and first-phase insulin secretion (acute insulin response [AIR]) were directly measured using the frequently sampled intravenous glucose tolerance test.

RESULTS

At the 5-year follow-up examination, 128 (15.5%) individuals had developed diabetes. Both S^I (odds ratio × 1 SD 0.50 [95% CI 0.37–0.68]) and AIR (0.51 [0.40–0.65]) were independent predictors of incident diabetes even after adjustment for age, sex, ethnicity, center, IGT, family history of diabetes, and BMI. The strength of the relation of S^I and AIR to incident diabetes was not significantly affected by potential interactions of age, sex, ethnicity, glucose tolerance, BMI, or family history of diabetes (P ≥ 0.15).

CONCLUSIONS

Both insulin sensitivity and β-cell function predict conversion to diabetes in different ethnic groups and various states of glucose tolerance, family history of diabetes, and obesity. The prevention of type 2 diabetes should focus on interventions that improve both insulin resistance and insulin secretion.Insulin resistance and insulin secretion are major predictors of type 2 diabetes, but much of the evidence is the result of studies that use surrogate measures of insulin resistance and β-cell function (1–4). There are few studies that have measured insulin resistance and secretion by direct methods. These studies have enrolled relatively few participants and have targeted individuals from a single ethnic group. In the study by Martin et al. (5), there were 25 incident cases of diabetes among 151 offspring of white parents who both had type 2 diabetes. In a subsequent report by Goldfine et al. (6), this cohort of individuals was compared with a cohort of 181 subjects with normal glucose tolerance (NGT) with only 6 incident cases of diabetes during a mean follow-up of 25 years (6). In the Pima Indian report, 200 subjects were studied and 38 developed type 2 diabetes (7). In a more recent study from the Netherlands, 101 white individuals with impaired glucose tolerance (IGT) were enrolled and 35 developed diabetes (8). Risk of progression to IGT and diabetes associated with direct measures of insulin sensitivity and secretion was also examined in 399 Pima Indians (9) and in 81 first-degree relatives of African Americans with type 2 diabetes (10). None of these studies adjusted their results for glucose tolerance status and adiposity. Furthermore, there are few data on how insulin resistance and secretion perform in different ethnic groups and various states of glucose tolerance, family history of diabetes, and obesity.Because the significance of insulin resistance and secretion could differ by ethnic group, parental history of diabetes, and obesity, we examined the heterogeneity of the relation of insulin resistance and β-cell function to future development of type 2 diabetes. The Insulin Resistance Atherosclerosis Study (IRAS) is a large epidemiological study on insulin resistance and cardiovascular risk factors among individuals of three ethnic groups (African Americans, Hispanics, and non-Hispanic whites) (11). Insulin sensitivity and first-phase insulin secretion were directly measured using the frequently sampled intravenous glucose tolerance test with MINMOD analysis.     

Association Between Iron Deficiency and A1C Levels Among Adults Without Diabetes in the National Health and Nutrition Examination Survey, 1999�C2006

OBJECTIVE

Iron deficiency has been reported to elevate A1C levels apart from glycemia. We examined the influence of iron deficiency on A1C distribution among adults without diabetes.

RESEARCH DESIGN AND METHODS

Participants included adults without self-reported diabetes or chronic kidney disease in the National Health and Nutrition Examination Survey 1999–2006 who were aged ≥18 years of age and had complete blood counts, iron studies, and A1C levels. Iron deficiency was defined as at least two abnormalities including free erythrocyte protoporphyrin >70 μg/dl erythrocytes, transferrin saturation <16%, or serum ferritin ≤15 μg/l. Anemia was defined as hemoglobin <13.5 g/dl in men and <12.0 g/dl in women.

RESULTS

Among women (n = 6,666), 13.7% had iron deficiency and 4.0% had iron deficiency anemia. Whereas 316 women with iron deficiency had A1C ≥5.5%, only 32 women with iron deficiency had A1C ≥6.5%. Among men (n = 3,869), only 13 had iron deficiency and A1C ≥5.5%, and only 1 had iron deficiency and A1C ≥6.5%. Among women, iron deficiency was associated with a greater odds of A1C ≥5.5% (odds ratio 1.39 [95% CI 1.11–1.73]) after adjustment for age, race/ethnicity, and waist circumference but not with a greater odds of A1C ≥6.5% (0.79 [0.33–1.85]).

CONCLUSIONS

Iron deficiency is common among women and is associated with shifts in A1C distribution from <5.5 to ≥5.5%. Further research is needed to examine whether iron deficiency is associated with shifts at higher A1C levels.A1C is formed by the glycation of the terminal valine of the β-chain of hemoglobin. It is used commonly as a screening test for diabetes in clinical practice (1). A1C may be less susceptible than other measures of glycemia to temporary fluctuations caused by diet, physical activity, or illness as well as differences in local testing standards; as a result, an expert committee has recently endorsed an A1C ≥6.5% as diagnostic for diabetes (1).Previous studies have reported that depletion of iron stores may alter the glycation rate of hemoglobin and elevate A1C concentrations, independent of glycemia (2). Iron deficiency may be present without associated anemia (3). Although iron deficiency is the most common nutritional deficiency (3), the clinical relevance of iron deficiency on the use of A1C as a screening test for diabetes has not been studied. Reproductive-age women are particularly vulnerable to iron deficiency, reflecting iron loss through menstruation and pregnancy. In the Third National Health and Nutrition Examination Survey (NHANES) 1988–1994 and later NHANES waves, >11% of women had iron deficiency (3,4).Using a recent population-based sample of U.S. adults, we examined the distribution of A1C by iron deficiency status among adults without known diabetes. We hypothesized that adults with iron deficiency would be more likely to have elevated A1C levels, even after consideration of fasting plasma glucose. We also hypothesized that any differences would persist after adjustment for other factors associated with A1C and iron deficiency, including age, race/ethnicity, and waist circumference.     

Type 2 diabetes in older well-functioning people: who is undiagnosed? Data from the Health, Aging, and Body Composition study.

OBJECTIVE: To assess, in an older population, the prevalence of diagnosed and undiagnosed diabetes, the number needed to screen (NNTS) to identify one individual with undiagnosed diabetes, and factors associated with undiagnosed diabetes. RESEARCH DESIGN AND METHODS: Socioeconomic and health-related factors were assessed at the baseline examination of the Health, Aging, and Body Composition (Health ABC) Study, a cohort of 3,075 well-functioning people aged 70-79 years living in Memphis, Tennessee and Pittsburgh, Pennsylvania (42% blacks and 48% men). Diabetes was defined according to the 1985 World Health Organization criteria (fasting glucose > or =7.8 mmol/l or 2-h glucose > or =11.1 mmol/l) and the 1997 American Diabetes Association criteria (fasting glucose > or =7.0 mmol/l). RESULTS: The prevalence of diagnosed and undiagnosed diabetes was 15.6 and 8.0%, respectively, among all participants (NNTS 10.6), 13.9 and 9.1% among white men (NNTS 9.5), 7.8 and 7.4% among white women (NNTS 12.4), 22.7 and 9.1% among black men (NNTS 8.5), and 21.6 and 6.2% among black women (NNTS 12.6). In multivariate analyses, compared with individuals without diabetes, individuals with undiagnosed diabetes were more likely to be men and were more likely to have a history of hypertension, higher BMI, and larger waist circumference. NNTS was lowest in men (9.1), individuals with hypertension (8.7), individuals in the highest BMI quartile (6.9), and individuals in the largest waist circumference quartile (6.8). CONCLUSIONS: In approximately one-third of all older people with diabetes, the condition remains undiagnosed. Screening for diabetes may be more efficient among men and individuals with hypertension, high BMI, and large waist circumference.