Associations of progression to diabetes and regression to normal glucose tolerance with development of cardiovascular and microvascular disease among people with impaired glucose tolerance: a secondary analysis of the 30 year Da Qing Diabetes Prevention Outcome Study.

AIMS/HYPOTHESIS: We aimed to determine associations of regression to normal glucose tolerance (NGT), maintaining impaired glucose tolerance (IGT) or progression to diabetes with subsequent risks of CVD and microvascular disease among Chinese adults with IGT. METHODS: We conducted an observational study among 540 participants in the Da Qing Diabetes Prevention Study, a 6 year lifestyle intervention trial in people with IGT, defined by 1985 WHO criteria as fasting plasma glucose <7.8 mmol/l and 2 h post-load plasma glucose ≥7.8 and <11.1 mmol/l. At the end of the trial, the groups that had regressed to NGT, remained with IGT or progressed to diabetes were identified. Participants were then followed for 24 years after completion of the trial, during which we compared the incidence and hazard ratios for CVD and microvascular disease in each group and estimated the differences in their median time to onset from parametric Weibull distribution models. RESULTS: At the end of the 6 year trial, 252 (46.7%) participants had developed diabetes, 114 (21.1%) had remained with IGT and 174 (32.2%) had regressed to NGT. Compared with those who developed diabetes during the trial, the median time to onset of diabetes was delayed by 14.86 years (95% CI 12.49, 17.25) in the NGT and 9.87 years (95% CI 8.12, 11.68) in the IGT groups. After completion of the trial, among those with diabetes, IGT and NGT, the 24 year cumulative incidence of CVD was 64.5%, 48.5% and 45.1%, respectively, and 36.8%, 21.7% and 16.5% for microvascular diseases. Compared with participants who had progressed to diabetes during the trial, those who regressed to NGT had a 37% (HR 0.63; 95% CI 0.47, 0.85) reduction in CVD incidence and a median delay of 7.45 years (95% CI 1.91, 12.99) in onset, and those who remained with IGT had a 34% (HR 0.66; 95% CI 0.47, 0.91) lower CVD incidence with a median delay in onset of 5.69 years (95% CI 1.0, 10.38). Participants with NGT had a 66% (HR 0.34; 95% CI 0.20, 0.56) lower incidence of microvascular diseases and a median delay in the onset of 18.66 years (95% CI 6.08, 31.24), and those remaining with IGT had a 52% (HR 0.48; 95% CI 0.29, 0.81) lower incidence with a median delay of 12.56 years (95% CI 2.49, 22.63). CONCLUSIONS/INTERPRETATION: People with IGT who reverted to NGT or remained with IGT at the end of the 6 year trial subsequently had significantly lower incidences of CVD and microvascular disease than those who had developed diabetes.

Efficacy of lifestyle intervention in adults with impaired glucose tolerance with and without impaired fasting plasma glucose: A post hoc analysis of Da Qing Diabetes Prevention Outcome Study.

AIMS: The extent that pre-diabetic fasting plasma glucose (FPG) levels influence the effectiveness of lifestyle interventions in preventing type 2 diabetes (T2DM) is uncertain. We aimed to determine if the outcome of lifestyle intervention in people with impaired glucose tolerance (IGT) differs in those with normal or impaired FPG levels. MATERIALS AND METHODS: Data were used from the Da Qing Diabetes Prevention Outcome Study, which was a 30-year follow-up of a 6-year randomized trial of lifestyle intervention in 576 people with IGT. We then conducted a post-hoc analysis to compare the efficacy of intervention to reduce the incidence of T2DM and its complications in those with baseline FPG <100 mg/dL and FPG ≥100 mg/dL. RESULTS: Lifestyle intervention reduced the cumulative incidence of T2DM by 37%-46% in those with baseline FPG <100 mg/dL and by 47%-51% in those with FPG ≥100 mg/dL. The FPG <100 mg/dL group had a lower cumulative incidence of diabetes and 6.41 years median delay in its onset compared with 2.21 years delay in the FPG ≥100 mg/dL group. In those with FPG <100 mg/dL intervention was associated with at least as great a reduction in cardiovascular disease and all-cause mortality as in the FPG ≥100 mg/dL group. CONCLUSIONS: Lifestyle intervention reduced the incidence of T2DM in people with IGT regardless of baseline FPG levels, and in those with FPG <100 mg/dL led to a substantial delay in its onset. All persons with IGT, with normal or impaired FPG levels, may benefit from lifestyle intervention to delay its onset and mitigate the incidence of T2DM.

Does diabetes prevention translate into reduced long-term vascular complications of diabetes?

The global epidemic of type 2 diabetes has prompted numerous studies and public health efforts to reduce its development. A variety of interventions, including lifestyle modifications and pharmacological agents directed at ameliorating the major risk factors for type 2 diabetes, are of proven efficacy in reducing the development of type 2 diabetes in people with impaired glucose tolerance. While prevention of the hyperglycaemia characteristic of diabetes is arguably an important, clinically relevant outcome, a more compelling outcome with greater clinical significance is the prevention or reduction of the relatively diabetes-specific microvascular and less-specific cardiovascular disease (CVD) complications associated with diabetes. These complications cause the majority of morbidity and excess mortality associated with diabetes. Any reduction in diabetes should, logically, also reduce the occurrence of its long-term complications; however, most diabetes prevention trials have not been of sufficient duration to allow such an evaluation. The limited long-term data, largely from the Da Qing Diabetes Prevention Study (DQDPS) and the Diabetes Prevention Program (DPP) and their respective follow-up studies (DQDPOS and DPPOS), suggest a reduction in microvascular complications and amelioration of CVD risk factors. Only the DQDPOS and Study to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM) studies have shown a reduction in CVD events and only DQDPOS has demonstrated a decrease in CVD and overall mortality. While these limited data are promising, whether diabetes prevention directly reduces complication-related morbidity and mortality remains unclear. Longer follow-up of prevention studies is needed to supplement the limited current clinical trial data, to help differentiate the effects of diabetes prevention itself from the means used to reduce diabetes development and to understand the balance among benefits, risks and costs of prevention.

Analysis of type 2 diabetes and obesity genetic variants in Mexican Pima Indians: Marked allelic differentiation among Amerindians at HLA.

Prevalence of diabetes and obesity in Mexican Pima Indians is low, while prevalence in US Pima Indians is high. Although lifestyle likely accounts for much of the difference, the role of genetic factors is not well explored. To examine this, we genotyped 359 single nucleotide polymorphisms, including established type 2 diabetes and obesity variants from genome-wide association studies (GWAS) and 96 random markers, in 342 Mexican Pimas. A multimarker risk score of obesity variants was associated with body mass index (BMI; ß = 0.81 kg/m2 per SD, P = 0.0066). The mean value of the score was lower in Mexican Pimas than in US Pimas (P = 4.3 × 10-11 ), and differences in allele frequencies at established loci could account for approximately 7% of the population difference in BMI; however, the difference in risk scores was consistent with evolutionary neutrality given genetic distance. To identify loci potentially under recent natural selection, allele frequencies at 283 variants were compared between US and Mexican Pimas, accounting for genetic distance. The largest differences were seen at HLA markers (e.g., rs9271720, difference = 0.75, P = 8.7 × 10-9 ); genetic distances at HLA were greater than at random markers (P = 1.6 × 10-46 ). Analyses of GWAS data in 937 US Pimas also showed sharing of alleles identical by descent at HLA that exceeds its genomic expectation (P = 7.0 × 10-10 ). These results suggest that, in addition to the widely recognized balancing selection at HLA, recent directional selection may also occur, resulting in marked allelic differentiation between closely related populations.

Filtration markers as predictors of ESRD and mortality in Southwestern American Indians with type 2 diabetes.

BACKGROUND: A growing number of serum filtration markers are associated with mortality and end-stage renal disease (ESRD) in adults. Whether ß-trace protein (BTP) and ß2-microglobulin (B2M) are associated with these outcomes in adults with type 2 diabetes is not known. STUDY DESIGN: Longitudinal cohort study. SETTING & PARTICIPANTS: 250 Pima Indians with type 2 diabetes (69% women; mean age, 42 years; mean diabetes duration, 11 years). PREDICTORS: Serum BTP, B2M, and glomerular filtration rate measured by iothalamate clearance (mGFR) or estimated using creatinine (eGFRcr) or cystatin C level (eGFRcys). OUTCOMES & MEASUREMENTS: Incident ESRD and all-cause mortality through December 2013. HRs were reported per interquartile range decrease of the inverse of BTP and B2M (1/BTP and 1/B2M) using Cox regression. Improvement in risk prediction with the addition of BTP or B2M level to established markers (eGFRcys with mGFR or eGFRcr) was evaluated using C statistics, continuous net reclassification improvement, and relative integrated discrimination improvement (RIDI). RESULTS: During a median follow-up of 14 years, 69 participants developed ESRD and 95 died. Both novel markers were associated with ESRD in multivariable models. BTP level remained statistically significant after further adjustment for mGFR (1/BTP, 1.53 [95% CI, 1.01-2.30]; 1/B2M, 1.54 [95% CI, 0.98-2.42]). B2M level was associated with mortality in multivariable models and after further adjustment for mGFR (HR, 2.12; 95% CI, 1.38-3.26). The addition of B2M level to established markers increased the C statistic for mortality but only weakly when assessed by either continuous net reclassification improvement or RIDI; none was improved for ESRD by the addition of these markers. LIMITATIONS: Small sample size, single measurements of markers. CONCLUSIONS: In Pima Indians with type 2 diabetes, BTP and, to a lesser extent, B2M levels were associated with ESRD. B2M level was associated with mortality after adjustment for traditional risk factors and established filtration markers. Further studies are warranted to confirm whether inclusion of B2M level in a multimarker approach leads to improved risk prediction for mortality in this population.

Changes in energy expenditure and physical activity over 15 years of environmental changes: The Maycoba project.

OBJECTIVE: This work aimed to parse out the role of changing environments on body composition, total energy expenditure, and physical activity in the Mexican Pima, a population experiencing rapid industrialization. METHODS: Using doubly labeled water, we compared energy expenditure and physical activity in a longitudinal cohort of Mexican Pima (n = 26; female: 12) in 1995 and 2010. Body mass and composition were assessed by bioimpedance analysis. To determine the effects of environmental factors on body weight independent of age, we compared the 1995 longitudinal cohort with an age- and sex-matched cross-sectional cohort (n = 26) in 2010. RESULTS: Body mass, fat mass, and fat-free mass all significantly increased between 1995 and 2010. Despite a 13% average increase in body weight, weight-adjusted total daily energy expenditure decreased significantly. Measured physical activity levels also decreased between 1995 and 2010, after we adjusted for weight. CONCLUSIONS: Our results suggest that the recent industrialization of the Maycoba region in Sonora, Mexico, has contributed to a decrease in physical activity, in turn contributing to weight gain and metabolic disease among the Mexican Pima.

Childhood obesity, other cardiovascular risk factors, and premature death.

BACKGROUND: The effect of childhood risk factors for cardiovascular disease on adult mortality is poorly understood. METHODS: In a cohort of 4857 American Indian children without diabetes (mean age, 11.3 years; 12,659 examinations) who were born between 1945 and 1984, we assessed whether body-mass index (BMI), glucose tolerance, and blood pressure and cholesterol levels predicted premature death. Risk factors were standardized according to sex and age. Proportional-hazards models were used to assess whether each risk factor was associated with time to death occurring before 55 years of age. Models were adjusted for baseline age, sex, birth cohort, and Pima or Tohono O'odham Indian heritage. RESULTS: There were 166 deaths from endogenous causes (3.4% of the cohort) during a median follow-up period of 23.9 years. Rates of death from endogenous causes among children in the highest quartile of BMI were more than double those among children in the lowest BMI quartile (incidence-rate ratio, 2.30; 95% confidence interval [CI], 1.46 to 3.62). Rates of death from endogenous causes among children in the highest quartile of glucose intolerance were 73% higher than those among children in the lowest quartile (incidence-rate ratio, 1.73; 95% CI, 1.09 to 2.74). No significant associations were seen between rates of death from endogenous or external causes and childhood cholesterol levels or systolic or diastolic blood-pressure levels on a continuous scale, although childhood hypertension was significantly associated with premature death from endogenous causes (incidence-rate ratio, 1.57; 95% CI, 1.10 to 2.24). CONCLUSIONS: Obesity, glucose intolerance, and hypertension in childhood were strongly associated with increased rates of premature death from endogenous causes in this population. In contrast, childhood hypercholesterolemia was not a major predictor of premature death from endogenous causes.

Pima Indian Contributions to Our Understanding of Diabetic Kidney Disease.

Prospective studies in informative populations are crucial to increasing our knowledge of disease. In this perspective, we describe a half century of studies in an American Indian population that transformed our understanding of kidney disease in type 2 diabetes, now recognized as the leading cause of kidney failure worldwide. Serial examinations conducted for many years that included the collection of data and samples across multiple domains captured an unprecedented volume of clinical, physiologic, morphometric, genomic, and transcriptomic data. This work permitted us to extensively characterize the course and determinants of diabetic kidney disease, its pathophysiologic underpinnings, and important secular trends of urgent concern to populations worldwide, including the emergence of youth-onset type 2 diabetes and its effect on development of diabetic kidney disease in midlife. By combining these data using the tools of integrative biology, we are developing new mechanistic insights into the development and progression of diabetic kidney disease in type 2 diabetes. These insights have already contributed to the identification and successful therapeutic targeting of a novel pathway in DKD. We anticipate that this work will continue to expand our understanding of this complex disease and influence its management in the coming years.

Accuracy of 1-Hour Plasma Glucose During the Oral Glucose Tolerance Test in Diagnosis of Type 2 Diabetes in Adults: A Meta-analysis.

OBJECTIVE: One-hour plasma glucose (1-h PG) during the oral glucose tolerance test (OGTT) is an accurate predictor of type 2 diabetes. We performed a meta-analysis to determine the optimum cutoff of 1-h PG for detection of type 2 diabetes using 2-h PG as the gold standard. RESEARCH DESIGN AND METHODS: We included 15 studies with 35,551 participants from multiple ethnic groups (53.8% Caucasian) and 2,705 newly detected cases of diabetes based on 2-h PG during OGTT. We excluded cases identified only by elevated fasting plasma glucose and/or HbA1c. We determined the optimal 1-h PG threshold and its accuracy at this cutoff for detection of diabetes (2-h PG ≥11.1 mmol/L) using a mixed linear effects regression model with different weights to sensitivity/specificity (2/3, 1/2, and 1/3). RESULTS: Three cutoffs of 1-h PG, at 10.6 mmol/L, 11.6 mmol/L, and 12.5 mmol/L, had sensitivities of 0.95, 0.92, and 0.87 and specificities of 0.86, 0.91, and 0.94 at weights 2/3, 1/2, and 1/3, respectively. The cutoff of 11.6 mmol/L (95% CI 10.6, 12.6) had a sensitivity of 0.92 (0.87, 0.95), specificity of 0.91 (0.88, 0.93), area under the curve 0.939 (95% confidence region for sensitivity at a given specificity: 0.904, 0.946), and a positive predictive value of 45%. CONCLUSIONS: The 1-h PG of ≥11.6 mmol/L during OGTT has a good sensitivity and specificity for detecting type 2 diabetes. Prescreening with a diabetes-specific risk calculator to identify high-risk individuals is suggested to decrease the proportion of false-positive cases. Studies including other ethnic groups and assessing complication risk are warranted.

The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study.

BACKGROUND: Intensive lifestyle interventions can reduce the incidence of type 2 diabetes in people with impaired glucose tolerance, but how long these benefits extend beyond the period of active intervention, and whether such interventions reduce the risk of cardiovascular disease (CVD) and mortality, is unclear. We aimed to assess whether intensive lifestyle interventions have a long-term effect on the risk of diabetes, diabetes-related macrovascular and microvascular complications, and mortality. METHODS: In 1986, 577 adults with impaired glucose tolerance from 33 clinics in China were randomly assigned to either the control group or to one of three lifestyle intervention groups (diet, exercise, or diet plus exercise). Active intervention took place over 6 years until 1992. In 2006, study participants were followed-up to assess the long-term effect of the interventions. The primary outcomes were diabetes incidence, CVD incidence and mortality, and all-cause mortality. FINDINGS: Compared with control participants, those in the combined lifestyle intervention groups had a 51% lower incidence of diabetes (hazard rate ratio [HRR] 0.49; 95% CI 0.33-0.73) during the active intervention period and a 43% lower incidence (0.57; 0.41-0.81) over the 20 year period, controlled for age and clustering by clinic. The average annual incidence of diabetes was 7% for intervention participants versus 11% in control participants, with 20-year cumulative incidence of 80% in the intervention groups and 93% in the control group. Participants in the intervention group spent an average of 3.6 fewer years with diabetes than those in the control group. There was no significant difference between the intervention and control groups in the rate of first CVD events (HRR 0.98; 95% CI 0.71-1.37), CVD mortality (0.83; 0.48-1.40), and all-cause mortality (0.96; 0.65-1.41), but our study had limited statistical power to detect differences for these outcomes. INTERPRETATION: Group-based lifestyle interventions over 6 years can prevent or delay diabetes for up to 14 years after the active intervention. However, whether lifestyle intervention also leads to reduced CVD and mortality remains unclear.

Morbidity and mortality after lifestyle intervention for people with impaired glucose tolerance: 30-year results of the Da Qing Diabetes Prevention Outcome Study.

BACKGROUND: Lifestyle interventions can delay the onset of type 2 diabetes in people with impaired glucose tolerance, but whether this leads subsequently to fewer complications or to increased longevity is uncertain. We aimed to assess the long-term effects of lifestyle interventions in people with impaired glucose tolerance on the incidence of diabetes, its complications, and mortality. METHODS: The original study was a cluster randomised trial, started in 1986, in which 33 clinics in Da Qing, China, were randomly assigned to either be a control clinic or provide one of three interventions (diet, exercise, or diet plus exercise) for 6 years for 577 adults with impaired glucose tolerance who usually receive their medical care from the clinics. Subsequently, participants were followed for up to 30 years to assess the effects of intervention on the incidence of diabetes, cardiovascular disease events, composite microvascular complications, cardiovascular disease death, all-cause mortality, and life expectancy. FINDINGS: Of the 577 participants, 438 were assigned to an intervention group and 138 to the control group (one refused baseline examination). After 30 years of follow-up, 540 (94%) of 576 participants were assessed for outcomes (135 in the control group, 405 in the intervention group). During the 30-year follow-up, compared with control, the combined intervention group had a median delay in diabetes onset of 3·96 years (95% CI 1·25 to 6·67; p=0·0042), fewer cardiovascular disease events (hazard ratio 0·74, 95% CI 0·59-0·92; p=0·0060), a lower incidence of microvascular complications (0·65, 0·45-0·95; p=0·025), fewer cardiovascular disease deaths (0·67, 0·48-0·94; p=0·022), fewer all-cause deaths (0·74, 0·61-0·89; p=0·0015), and an average increase in life expectancy of 1·44 years (95% CI 0·20-2·68; p=0·023). INTERPRETATION: Lifestyle intervention in people with impaired glucose tolerance delayed the onset of type 2 diabetes and reduced the incidence of cardiovascular events, microvascular complications, and cardiovascular and all-cause mortality, and increased life expectancy. These findings provide strong justification to continue to implement and expand the use of such interventions to curb the global epidemic of type 2 diabetes and its consequences. FUNDING: US Centers for Disease Control and Prevention, WHO, Chinese Center for Disease Control and Prevention, World Bank, Ministry of Public Health of the People's Republic of China, Da Qing First Hospital, China-Japan Friendship Hospital, and National Center for Cardiovascular Diseases & Fuwai Hospital.

Prevention of diabetes in women with a history of gestational diabetes: effects of metformin and lifestyle interventions.

CONTEXT: A past history of gestational diabetes mellitus (GDM) confers a very high risk of postpartum development of diabetes, particularly type 2 diabetes. OBJECTIVE: The Diabetes Prevention Program (DPP) sought to identify individuals with impaired glucose tolerance (IGT) and intervene in an effort to prevent or delay their progression to diabetes. This analysis examined the differences between women enrolled in DPP with and without a reported history of GDM. DESIGN: The DPP was a randomized, controlled clinical trial. SETTING: The study was a multicenter, National Institutes of Health-sponsored trial carried out at 27 centers including academic and Indian Health Services sites. PATIENTS: A total of 2190 women were randomized into the DPP and provided information for past history of GDM. This analysis addressed the differences between those 350 women providing a past history of GDM and those 1416 women with a previous live birth but no history of GDM. INTERVENTIONS: Subjects were randomized to either standard lifestyle and placebo or metformin therapy or to an intensive lifestyle intervention. MAIN OUTCOMES: The primary outcome was the time to development of diabetes ascertained by semiannual fasting plasma glucose and annual oral glucose tolerance testing. Assessments of insulin secretion and insulin sensitivity were also performed. RESULTS: Whereas entering the study with similar glucose levels, women with a history of GDM randomized to placebo had a crude incidence rate of diabetes 71% higher than that of women without such a history. Among women reporting a history of GDM, both intensive lifestyle and metformin therapy reduced the incidence of diabetes by approximately 50% compared with the placebo group, whereas this reduction was 49 and 14%, respectively in parous women without GDM. These data suggest that metformin may be more effective in women with a GDM history as compared with those without. CONCLUSIONS: Progression to diabetes is more common in women with a history of GDM compared with those without GDM history despite equivalent degrees of IGT at baseline. Both intensive lifestyle and metformin are highly effective in delaying or preventing diabetes in women with IGT and a history of GDM.

Predictive power of sequential measures of albuminuria for progression to ESRD or death in Pima Indians with type 2 diabetes.

BACKGROUND: To determine whether historic albuminuria measurements provide additional predictive value for diabetic end-stage renal disease (ESRD) and natural mortality over the most recent measurement, ie, whether "regression" from high albuminuria has a different prognosis than stability at the lower level. STUDY DESIGN: Observational longitudinal study. SETTING & PARTICIPANTS: Pima Indians 15 years or older with type 2 diabetes and at least 2 consecutive measurements of urinary albumin-creatinine ratio (ACR) within 6 years. PREDICTORS: Sequential measurements of urinary ACR. OUTCOMES & MEASUREMENTS: Proportional hazards analyses were used to estimate the risk of ESRD and natural death associated with the first and second ACR measurement. The ability of these highly correlated variables to predict outcome was compared with receiver operating characteristic curves calculated by means of the generalized c statistic. RESULTS: In 983 subjects, 136 developed ESRD and 180 died of natural causes during a maximum follow-up of 12.6 years. Each doubling in the second ACR was associated with a 1.71-fold greater incidence of ESRD (95% confidence interval, 1.54 to 1.89) and 1.16-fold greater natural mortality (95% confidence interval, 1.07 to 1.27) adjusted for age, sex, diabetes duration, and antihypertensive medication. The addition of the first ACR measurement to the model did not add to the predictive value for ESRD or mortality. In pairwise comparisons of c statistics, the second ACR was a significantly better predictor of ESRD than the first ACR. LIMITATIONS: The predictive value of ACR measurements is decreased to the extent that its precision is based on a single measure. CONCLUSION: The predictive power of the latest ACR for ESRD and natural mortality in patients with diabetes is not enhanced by knowledge of the preceding ACR. Therefore, ACR changes over time, ie, regression or progression, add minimal predictive value beyond the latest measurement in the series.

Serum lipids and mortality in an American Indian population: A longitudinal study.

BACKGROUND: In Caucasians, lower triglycerides (TG), total or LDL cholesterol and high HDL cholesterol are generally associated with lower mortality. However, low cholesterol is associated with higher mortality in some Asian populations. This study examines the relationship between serum lipids and mortality in American Indians. METHODS: 2125 American Indians aged ≥40years were examined biennially between 1993 and 2007. Vital status was determined through 2011. Mortality rates, adjusted for age, sex and diabetes, were calculated using Poisson regression. RESULTS: The median baseline age was 46years and 61% were women. Over a median follow-up of 10.1years, 522 deaths occurred. Relationships between baseline lipids, except for HDL cholesterol, and all-cause mortality were negative and linear in persons without diabetes and U-shaped in persons with diabetes. For HDL cholesterol, the relationship was U-shaped in the total cohort. Cardiovascular mortality was positively associated with total, LDL and non-HDL cholesterol whereas lower lipid concentrations were adversely associated with mortality from liver disease or external causes, except for HDL cholesterol, where associations were positive. CONCLUSION: The common belief that low cholesterol and TG are beneficial for health is not universally observed; evidence suggests increased mortality at both ends of the cholesterol and TG distributions.

Influence of improvement or worsening of glucose tolerance on risk of stroke in persons with impaired glucose tolerance.

BACKGROUND AND AIM: We sought to determine the effect of regression to normal glucose tolerance (NGT) or progression to diabetes in early years of impaired glucose tolerance (IGT) on subsequent risk of stroke. METHODS: In 1986, 576 adults aged 25 years and older with impaired glucose tolerance in Da Qing, China, were randomly assigned by clinic to control, diet, exercise, or diet plus exercise intervention groups for a six-year period. Subsequently participants received medical care in their local clinics. We tracked participants for additional 17 years to ascertain stroke events and other outcomes. RESULTS: At the end of 6-year intervention trial follow-up, 272 (50.2%) had progressed to diabetes, 169 (31.2%) regressed to normal glucose tolerance, and 101 (18.6%) remained impaired glucose tolerance. During the subsequent 17-year follow-up, 173 (31.9%) developed a stroke, 26.7% of normal glucose tolerances, 30.7% of impaired glucose tolerances, and 36.1% of those with diabetes. After controlling for age, sex, baseline blood pressure, smoking, total cholesterol, previous cardiovascular disease and intervention group, those who developed diabetes in the first six years had a higher incidence of stroke than those who reverted to normal glucose tolerance (HR = 1.49, 95% CI 1.01-2.19, p = 0.04), whereas for those who remained impaired glucose tolerance compared to those who regressed to normal glucose tolerance the HR was 1.25 (95% CI 0.80-1.93; p = 0.30). A 1-mmol/L increase in both fasting and 2-h post-load plasma glucose from entry to end of the six-year trial was significantly associated with a higher risk of development of stroke in the subsequent 17 years, respectively (HR = 1.07, 95% CI 1.03-1.11, p < 0.0001 for fasting glucose, HR = 1.05, 95% CI 1.02-1.09, p = 0.007 for 2-h post-load plasma glucose). CONCLUSIONS: Among Chinese adults with impaired glucose tolerance, early progression to diabetes predicted a higher risk of stroke, compared those who regressed to normal glucose tolerance.

Effects of traditional and western environments on prevalence of type 2 diabetes in Pima Indians in Mexico and the U.S.

OBJECTIVE: Type 2 diabetes and obesity have genetic and environmental determinants. We studied the effects of different environments on these diseases in Pima Indians in Mexico and the U.S. RESEARCH DESIGN AND METHODS: Adult Pima-Indian and non-Pima populations in the Sierra Madre mountains of Mexico were examined using oral glucose tolerance tests and assessments for obesity, physical activity, and other risk factors. Results were compared with those from Pima Indians in Arizona. Both Pima populations were typed for DNA polymorphisms to establish their genetic similarity. RESULTS: The age- and sex-adjusted prevalence of type 2 diabetes in the Mexican Pima Indians (6.9%) was less than one-fifth that in the U.S. Pima Indians (38%) and similar to that of non-Pima Mexicans (2.6%). The prevalence of obesity was similar in the Mexican Pima Indians (7% in men and 20% in women) and non-Pima Mexicans (9% in men and 27% in women) but was much lower than in the U.S. Pima Indians. Levels of physical activity were much higher in both Mexican groups than in the U.S. Pima Indians. The two Pima groups share considerable genetic similarity relative to other Native Americans. CONCLUSIONS: The much lower prevalence of type 2 diabetes and obesity in the Pima Indians in Mexico than in the U.S. indicates that even in populations genetically prone to these conditions, their development is determined mostly by environmental circumstances, thereby suggesting that type 2 diabetes is largely preventable. This study provides compelling evidence that changes in lifestyle associated with Westernization play a major role in the global epidemic of type 2 diabetes.

Electrocardiographic abnormalities predict deaths from cardiovascular disease and ischemic heart disease in Pima Indians with type 2 diabetes.

BACKGROUND: The association between electrocardiographic (ECG) abnormalities and deaths from cardiovascular diseases (CVD) and ischemic heart disease (IHD) has been reported in the general population, but there is little information regarding persons with type 2 diabetes. METHODS: Minor and major ECG abnormalities were identified and classified according to the Minnesota Code in a longitudinal study of 1605 Pima Indians aged > or =35 years with type 2 diabetes. Underlying causes of death were determined by review of all available clinical records, autopsy reports, medical examiners' findings, and death certificates. RESULTS: During a median follow-up of 14.1 years (range 0.1 to 33.8 years), there were 190 CVD deaths, 135 (71.1%) of which were attributable to IHD. The age-adjusted CVD death rates in men with none, minor, and major ischemic ECG abnormalities were 7.3, 12.2 and 27.8, and in women, 4.3, 4.8 and 12.5 per 1000 person-years, respectively. After adjustment for other co-variables in a multiple proportional hazards model, subjects with minor and major ischemic abnormalities on ECG had 1.22 (95% CI, 0.76-1.97) and 1.83 (95% CI, 1.21-2.76) times the CVD death rate, and 1.32 (95% CI, 0.70-2.50) and 2.12 (95% CI, 1.26-3.57) times the IHD death rate of those with no ischemic ECG abnormalities, respectively. CONCLUSIONS: The CVD and IHD death rates were higher in men and in subjects with major ischemic ECG abnormalities. Major ischemic abnormalities on ECG predicted death after accounting for other cardiovascular risk factors, including proteinuria.