Baiju R. Shah

Increased Risk of Cardiovascular Disease in Young Women Following Gestational Diabetes Mellitus

OBJECTIVE—To determine whether women with gestational diabetes mellitus (GDM) have an increased risk of cardiovascular disease (CVD) following pregnancy. RESEARCH DESIGN AND METHODS—All women aged 20–49 years with live births between April 1994 and March 1997 in Ontario, Canada, were identified. Women with GDM were matched with 10 women without GDM and were followed for CVD. RESULTS—The matched cohorts included 8,191 women with GDM and 81,262 women without GDM. Mean age at entry was 31 years, and median follow-up was 11.5 years. The hazard ratio for CVD events was 1.71 (95% CI 1.08–2.69). After adjustment for subsequent type 2 diabetes, the hazard ratio was attenuated (1.13 [95% CI 0.67–1.89]). CONCLUSIONS—Young women with GDM had a substantially increased risk for CVD compared with women without GDM. Much of this increased risk was attributable to subsequent development of type 2 diabetes.

Risk of incident diabetes among patients treated with statins: population based study

Objective To examine the risk of new onset diabetes among patients treated with different HMG-CoA reductase inhibitors (statins). Design Population based cohort study with time to event analyses to estimate the relation between use of particular statins and incident diabetes. Hazard ratios were calculated to determine the effect of dose and type of statin on the risk of incident diabetes. Setting Ontario, Canada. Participants All patients aged 66 or older without diabetes who started treatment with statins from 1 August 1997 to 31 March 2010. The analysis was restricted to new users who had not been prescribed a statin in at least the preceding year. Patients with established diabetes before the start of treatment were excluded. Interventions Treatment with statins. Main outcome measure Incident diabetes. Results Compared with pravastatin (the reference drug in all analyses), there was an increased risk of incident diabetes with atorvastatin (adjusted hazard ratio 1.22, 95% confidence interval 1.15 to 1.29), rosuvastatin (1.18, 1.10 to 1.26), and simvastatin (1.10, 1.04 to 1.17). There was no significantly increased risk among people who received fluvastatin (0.95, 0.81 to 1.11) or lovastatin (0.99, 0.86 to 1.14). The absolute risk for incident diabetes was about 31 and 34 events per 1000 person years for atorvastatin and rosuvastatin, respectively. There was a slightly lower absolute risk with simvastatin (26 outcomes per 1000 person years) compared with pravastatin (23 outcomes per 1000 person years). Our findings were consistent regardless of whether statins were used for primary or secondary prevention of cardiovascular disease. Although similar results were observed when statins were grouped by potency, the risk of incident diabetes associated with use of rosuvastatin became non-significant (adjusted hazard ratio 1.01, 0.94 to 1.09) when dose was taken into account. Conclusions Compared with pravastatin, treatment with higher potency statins, especially atorvastatin and simvastatin, might be associated with an increased risk of new onset diabetes.

Deriving Ethnic-Specific BMI Cutoff Points for Assessing Diabetes Risk

OBJECTIVE The definition of obesity (BMI ≥30 kg/m2), a key risk factor of diabetes, is widely used in white populations; however, its appropriateness in nonwhite populations has been questioned. We compared the incidence rates of diabetes across white, South Asian, Chinese, and black populations and identified equivalent ethnic-specific BMI cutoff values for assessing diabetes risk. RESEARCH DESIGN AND METHODS We conducted a multiethnic cohort study of 59,824 nondiabetic adults aged ≥30 years living in Ontario, Canada. Subjects were identified from Statistics Canada’s population health surveys and followed for up to 12.8 years for diabetes incidence using record linkages to multiple health administrative databases. RESULTS The median duration of follow-up was 6 years. After adjusting for age, sex, sociodemographic characteristics, and BMI, the risk of diabetes was significantly higher among South Asian (hazard ratio 3.40, P < 0.001), black (1.99, P < 0.001), and Chinese (1.87, P = 0.002) subjects than among white subjects. The median age at diagnosis was lowest among South Asian (aged 49 years) subjects, followed by Chinese (aged 55 years), black (aged 57 years), and white (aged 58 years) subjects. For the equivalent incidence rate of diabetes at a BMI of 30 kg/m2 in white subjects, the BMI cutoff value was 24 kg/m2 in South Asian, 25 kg/m2 in Chinese, and 26 kg/m2 in black subjects. CONCLUSIONS South Asian, Chinese, and black subjects developed diabetes at a higher rate, at an earlier age, and at lower ranges of BMI than their white counterparts. Our findings highlight the need for designing ethnically tailored prevention strategies and for lowering current targets for ideal body weight for nonwhite populations.

Type 2 Diabetes, Medication-Induced Diabetes, and Monogenic Diabetes in Canadian Children: A Prospective National Surveillance Study

OBJECTIVE To determine in Canadian children aged <18 years the 1) incidence of type 2 diabetes, medication-induced diabetes, and monogenic diabetes; 2) clinical features of type 2 diabetes; and 3) coexisting morbidity associated with type 2 diabetes at diagnosis. RESEARCH DESIGN AND METHODS This Canadian prospective national surveillance study involved a network of pediatricians, pediatric endocrinologists, family physicians, and adult endocrinologists. Incidence rates were calculated using Canadian Census population data. Descriptive statistics were used to illustrate demographic and clinical features. RESULTS From a population of 7.3 million children, 345 cases of non–type 1 diabetes were reported. The observed minimum incidence rates of type 2, medication-induced, and monogenic diabetes were 1.54, 0.4, and 0.2 cases per 100,000 children aged <18 years per year, respectively. On average, children with type 2 diabetes were aged 13.7 years and 8% (19 of 227) presented before 10 years. Ethnic minorities were overrepresented, but 25% (57 of 227) of children with type 2 diabetes were Caucasian. Of children with type 2 diabetes, 95% (206 of 216) were obese and 37% (43 of 115) had at least one comorbidity at diagnosis. CONCLUSIONS This is the first prospective national surveillance study in Canada to report the incidence of type 2 diabetes in children and also the first in the world to report the incidence of medication-induced and monogenic diabetes. Rates of type 2 diabetes were higher than expected with important regional variation. These results support recommendations that screening for comorbidity should occur at diagnosis of type 2 diabetes.

Mild glucose intolerance in pregnancy and risk of cardiovascular disease: a population-based cohort study

Background: Pregnant women commonly receive screening for gestational diabetes mellitus by use of a 50 g glucose challenge test, followed by a diagnostic oral glucose tolerance test for those whose glucose challenge test result is abnormal. Although women with gestational diabetes have an increased risk of cardiovascular disease, it is not known whether mild glucose intolerance during pregnancy is also associated with cardiovascular disease. Thus, we sought to determine whether pregnant women with an abnormal glucose challenge test result but without gestational diabetes have an increased risk of cardiovascular disease. Methods: We conducted a retrospective population-based cohort study that included all women in Ontario aged 20–49 years with live deliveries between April 1994 and March 1998. We excluded women with pregestational diabetes. The population was stratified into 3 cohorts: women with gestational diabetes (n = 13 888); women who received an antepartum oral glucose tolerance test (suggestive of an abnormal result of the glucose challenge test) but who did not have gestational diabetes (n = 71 831); and women who did not receive an oral glucose tolerance test (suggestive of a normal result of the glucose challenge test) (n = 349 977). The primary outcome was cardiovascular disease (admission to hospital for acute myocardial infarction, coronary bypass, coronary angioplasty, stroke or carotid endarterectomy). Results: Compared with women who did not receive an oral glucose tolerance test, women with gestational diabetes and women who received an oral glucose tolerance test but did not have gestational diabetes had a higher risk of cardiovascular disease over 12.3 years of median follow-up (adjusted hazard ratio [HR] for women with gestational diabetes 1.66, 95% confidence interval [CI] 1.30–2.13, p < 0.001; adjusted HR for those with an oral glucose test but not gestational diabetes 1.19, 95% CI 1.02–1.39, p = 0.03). Interpretation: Mild glucose intolerance in pregnancy may be associated with an increased risk of cardiovascular disease.

Markers of Access to and Quality of Primary Care for Aboriginal People in Ontario, Canada

OBJECTIVES We evaluated primary care accessibility and quality for Ontarios aboriginal population. METHODS We compared a defined aboriginal cohort with nonaboriginal populations with analogous geographic isolation and low socioeconomic status. We determined rates of hospitalization for the following indicators of adequacy of primary care: ambulatory care-sensitive (ACS) conditions and utilization of referral care-sensitive (RCS) procedures from administrative databases. RESULTS ACS hospitalization rates, relative to the general population, were 2.54, 1.50, and 1.14 for the aboriginal population, the geographic control populations, and the socioeconomic control populations, respectively. The relative RCS procedure utilization rates were 0.64, 0.91, and 1.00, respectively. CONCLUSIONS The increased ACS hospitalization rate and reduced RCS procedure utilization rate suggest that northern Ontarios aboriginal residents have insufficient or ineffective primary care.

Trends in Incidence of Diabetes in Pregnancy and Serious Perinatal Outcomes: A Large, Population-Based Study in Ontario, Canada, 1996–2010

OBJECTIVE Women with diabetes in pregnancy have high rates of pregnancy complications. Our aims were to explore trends in the incidence of diabetes in pregnancy and examine whether the risk of serious perinatal outcomes has changed. RESEARCH DESIGN AND METHODS We performed a population-based cohort study of 1,109,605 women who delivered in Ontario, Canada, between 1 April 1996 and 31 March 2010. We categorized women as gestational diabetes (GDM) (n = 45,384), pregestational diabetes (pre-GDM) (n = 13,278), or no diabetes (n = 1,050,943). The annual age-adjusted rates of diabetes in pregnancy were calculated, and rates of serious perinatal outcomes were compared between groups and by year using Poisson regression. RESULTS The age-adjusted rate of both GDM (2.7–5.6%, P < 0.001) and pre-GDM (0.7–1.5%, P < 0.001) doubled from 1996 to 2010. The rate of congenital anomalies declined by 23%, whereas the rate of perinatal mortality did not change significantly. However, compared with women with no diabetes, women with pre-GDM and GDM faced an increased risk of congenital anomalies (relative risk 1.86 [95% CI 1.49–2.33] and 1.26 [1.09–1.45], respectively), and perinatal mortality remained elevated in women with pre-GDM (2.33 [1.59–3.43]). CONCLUSIONS The incidence of both GDM and pre-GDM in pregnancy has doubled over the last 14 years, and the overall burden of diabetes in pregnancy on society is growing. Although congenital anomaly rates have declined in women with diabetes, perinatal mortality rates remain unchanged, and the risk of both remains significantly elevated compared with nondiabetic women. Increased efforts are needed to reduce these adverse outcomes.

Surname lists to identify South Asian and Chinese ethnicity from secondary data in Ontario, Canada: a validation study

BackgroundSurname lists are useful for identifying cohorts of ethnic minority patients from secondary data sources. This study sought to develop and validate lists to identify people of South Asian and Chinese origin.MethodsComprehensive lists of South Asian and Chinese surnames were reviewed to identify those that uniquely belonged to the ethnic minority group. Surnames that were common in other populations, communities or ethnic groups were specifically excluded. These surname lists were applied to the Registered Persons Database, a registry of the health card numbers assigned to all residents of the Canadian province of Ontario, so that all residents were assigned to South Asian ethnicity, Chinese ethnicity or the General Population. Ethnic assignment was validated against self-identified ethnicity through linkage with responses to the Canadian Community Health Survey.ResultsThe final surname lists included 9,950 South Asian surnames and 1,133 Chinese surnames. All 16,688,384 current and former residents of Ontario were assigned to South Asian ethnicity, Chinese ethnicity or the General Population based on their surnames. Among 69,859 respondents to the Canadian Community Health Survey, both lists performed extremely well when compared against self-identified ethnicity: positive predictive value was 89.3% for the South Asian list, and 91.9% for the Chinese list. Because surnames shared with other ethnic groups were deliberately excluded from the lists, sensitivity was lower (50.4% and 80.2%, respectively).ConclusionsThese surname lists can be used to identify cohorts of people with South Asian and Chinese origins from secondary data sources with a high degree of accuracy. These cohorts could then be used in epidemiologic and health service research studies of populations with South Asian and Chinese origins.

The impact of diabetes on cardiovascular risk factors and outcomes in a native Canadian population

We measured cardiovascular disease (CVD) risk factors and their relationship to glucose intolerance in a Native Canadian population with very high rates of Type 2 diabetes mellitus. Five hundred and twenty five study-eligible Ojibwa-Cree individuals age 18 and over in the community of Sandy Lake, Canada who had participated in a population-based survey were studied. Diabetes status, plasma concentrations of total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), calculated low density lipoprotein-cholesterol (LDL-C), waist/hip ratio (WHR), BMI, systolic and diastolic BP, and history of smoking were compared to a standard national population. Extremely high rates of obesity (BMI and WHR) were identified in the study population and were associated with increasing glucose intolerance for both males and females. Rates of smoking exceeded 70 and 80% in females and males, respectively. Interestingly, despite obesity individuals who had normal glucose tolerance had significantly lower rates of high risk TC, TG, LDL-C, and HDL-C levels compared to a national Canadian population survey. However, with worsening glucose intolerance, TC, TG, LDL-C and HDL-C dramatically deteriorated in comparison to nationally published levels. These changes in cardiovascular risk factors, as a consequence of diabetes, appear to result in increased clinical outcomes. Admission to hospital for Ischemic Heart Disease (IHD) for Sandy Lake residents increased from a rate of 34.8/10,000 to 109.1/10,000 in 15 years. Although this and similar populations have historically reported low rates of CVD, the impact of diabetes on lipid risk factor is having devastating consequences on cardiovascular outcomes. This trend is expected to continue unless the high rates of diabetes can be modified.

Preeclampsia as a Risk Factor for Diabetes: A Population- Based Cohort Study

Denice Feig and colleagues assess the association between gestational diabetes, gestational hypertension, and preeclampsia and the development of future diabetes in a database analysis of pregnant women in Ontario, Canada.