we used administrative data from two canadian provinces ( british columbia 19932006 and alberta 19942007 ) that comprise 44% of all chinese and 34% of all south asian people in canada ( 6 ) . hospital discharge abstracts include all inpatient services for all hospitals within these provinces and contain primary and secondary discharge diagnosis codes of the icd-9 and icd-10 , with up to 25 diagnosis fields per individual admission . physician claims and hospital discharge data are updated daily and include all patients with provincial health insurance . under a universal health care system , virtually all residents of these provinces are covered by health insurance ensuring completeness of data . the provincial population registry contains surname , birth date , sex , and postal code on residents of the province . population counts from provincial registries correspond to census population estimates ( 7 ) , but , unlike census data , provide actual counts in inter - census years . all deaths are reported to the vital statistics database , and date of death was obtained by linking to vital statistics via a unique personal health number . individuals with diabetes were defined as those with an icd-9 or icd-10 code for diabetes ( icd-9-cm : 250.x ; icd-10 : e109 , e119 , e139 , e149 , e101 , e111 , e131 , e141 , e105 , e115 , e135 , and e145 ) for at least one hospital discharge abstract or two physician claims within 2 years . patients aged < 35 years were excluded to reduce the misclassification of type 2 diabetes as type 1 diabetes . patients with gestational diabetes mellitus , identified with coding for an obstetrical event within 5 months of diabetes diagnosis were also excluded . this coding algorithm was extensively validated against physician diagnosis of diabetes across sex , age - groups , and rural / urban residents and among those with and without comorbid conditions with a sensitivity of 92.3% , specificity of 96.9% , and a positive predictive value ( ppv ) of 77% ( 8,9 ) . we used validated surname analysis to categorize patients as south asian ( from pakistan , india , or bangladesh ) or chinese ( from china , taiwan , or hong kong ) using surnames recorded in provincial registries . compared with self - report , the sensitivity for the quan surname algorithm for chinese ethnicity was 78% , specificity was 99.7% , and ppv was 81% ( 10 ) . for the nam pehchan algorithm for south asian ethnicity , the sensitivity was 9094% , specificity was 99.4% , and ppv was 6396% ( 1113 ) . all remaining patients are referred to as  white  because this group is largely ( 93.2% ) composed of white , nonvisible minority individuals ( 6 ) . to determine incident cases patients with incident cases had a minimum of 3 previous years without any coding for diabetes in hospital or physicians claims files to minimize misclassifying prevalent cases as incident ( 98.9% of patients in each ethnic group still had nondiabetes physician visits in this time period ) . thus , incident cases are determined for 19972003 . to avoid falsely attributing the absence of diabetes diagnosis to newly arrived immigrants , we only included those patients with health insurance registration for at least 3 years before their diabetes diagnosis . to control for severity of illness at the time of diagnosis of diabetes , we measured clinical variables from the charlson comorbidity index validated to predict mortality in patients with type 2 diabetes ( 14 ) . socioeconomic status ( ses ) ses data were missing for 11,665 patients ( 2.5% chinese , 2.9% south asian , and 4.4% white ) . secondary outcomes included hospitalization for ami , acute stroke , or heart failure and were determined using validated coding algorithms in hospital discharge abstracts : ami ( icd-9 410 ; icd-10 i21 ) , ppv 0.95 ( 15 ) ; stroke ( icd-9 430 , 431 , 434 , and 436 ; icd-10 i60-i62 , i63.3-i63.5 , i63.8 , i63.9 , and i64 ) , ppv 0.850.98 ( 16 ) ; and heart failure ( icd-9 428.x ; icd-10 i5o ) , ppv 0.84 ( 17 ) . time to event was assessed up to 31 march 2006 for british columbia and to 31 march 2007 for alberta with up to 10 years follow - up ( median 4.0 years ) . patients were censored if they moved out of the province or reached the end of the observation period . we determined age - specific ( reported for the most recent fiscal year , 20032004 ) and age - standardized incidence of diagnosed diabetes for each ethnic and sex group . yearly incidence of diagnosed diabetes ( per 1,000 population ) was calculated using new cases of diabetes for each group as the numerator with the corresponding population count as the denominator for the most recent 5-year time period ( 19992003 ) . annual population counts for each ethnic and sex group were determined by applying the surname algorithms to the annual provincial registry population counts , minimizing denominator bias . we used direct age standardization for each group with the total provincial population in the same fiscal year as the reference group . poisson regression analysis was used to compare incidence rates between ethnic and sex groups and linear regression was used to determine change in incidence over time . cox proportional hazards models were constructed and stratified by sex , with adjustment for province , ses quintile , age in 5-year categories , previous history of ami , heart failure , cerebrovascular disease , peripheral arterial disease , renal impairment , cancer , dementia , chronic pulmonary disease , hypertension , rheumatic disease , peptic ulcer disease , liver disease , hemiplegia , metastatic carcinoma , and aids / hiv . we also conducted sensitivity analyses using the british columbia cohort by additionally adjusting for insulin , metformin , statin , or ace inhibitor prescribing within 5 years of diagnosis using a province - wide prescription drug database ( pharmanet ) only available in british columbia . all analyses were conducted with sas ( version 9.1.3 ) and graphs were plotted using r. this study was approved by the local ethics institutional review boards . we used administrative data from two canadian provinces ( british columbia 19932006 and alberta 19942007 ) that comprise 44% of all chinese and 34% of all south asian people in canada ( 6 ) . hospital discharge abstracts include all inpatient services for all hospitals within these provinces and contain primary and secondary discharge diagnosis codes of the icd-9 and icd-10 , with up to 25 diagnosis fields per individual admission . physician claims and hospital discharge data are updated daily and include all patients with provincial health insurance . under a universal health care system , virtually all residents of these provinces are covered by health insurance ensuring completeness of data . the provincial population registry contains surname , birth date , sex , and postal code on residents of the province . population counts from provincial registries correspond to census population estimates ( 7 ) , but , unlike census data , provide actual counts in inter - census years . all deaths are reported to the vital statistics database , and date of death was obtained by linking to vital statistics via a unique personal health number . individuals with diabetes were defined as those with an icd-9 or icd-10 code for diabetes ( icd-9-cm : 250.x ; icd-10 : e109 , e119 , e139 , e149 , e101 , e111 , e131 , e141 , e105 , e115 , e135 , and e145 ) for at least one hospital discharge abstract or two physician claims within 2 years . patients aged < 35 years were excluded to reduce the misclassification of type 2 diabetes as type 1 diabetes . patients with gestational diabetes mellitus , identified with coding for an obstetrical event within 5 months of diabetes diagnosis were also excluded . this coding algorithm was extensively validated against physician diagnosis of diabetes across sex , age - groups , and rural / urban residents and among those with and without comorbid conditions with a sensitivity of 92.3% , specificity of 96.9% , and a positive predictive value ( ppv ) of 77% ( 8,9 ) . we used validated surname analysis to categorize patients as south asian ( from pakistan , india , or bangladesh ) or chinese ( from china , taiwan , or hong kong ) using surnames recorded in provincial registries . compared with self - report , the sensitivity for the quan surname algorithm for chinese ethnicity was 78% , specificity was 99.7% , and ppv was 81% ( 10 ) . for the nam pehchan algorithm for south asian ethnicity , the sensitivity was 9094% , all remaining patients are referred to as  white  because this group is largely ( 93.2% ) composed of white , nonvisible minority individuals ( 6 ) . to determine incident cases , we identified all patients in whom diabetes was diagnosed at each fiscal year . patients with incident cases had a minimum of 3 previous years without any coding for diabetes in hospital or physicians claims files to minimize misclassifying prevalent cases as incident ( 98.9% of patients in each ethnic group still had nondiabetes physician visits in this time period ) . thus , incident cases are determined for 19972003 . to avoid falsely attributing the absence of diabetes diagnosis to newly arrived immigrants , we only included those patients with health insurance registration for at least 3 years before their diabetes diagnosis . to control for severity of illness at the time of diagnosis of diabetes , we measured clinical variables from the charlson comorbidity index validated to predict mortality in patients with type 2 diabetes ( 14 ) . socioeconomic status ( ses ) was assessed using area level median income based on the patient 's postal code . ses data were missing for 11,665 patients ( 2.5% chinese , 2.9% south asian , and 4.4% white ) . secondary outcomes included hospitalization for ami , acute stroke , or heart failure and were determined using validated coding algorithms in hospital discharge abstracts : ami ( icd-9 410 ; icd-10 i21 ) , ppv 0.95 ( 15 ) ; stroke ( icd-9 430 , 431 , 434 , and 436 ; icd-10 i60-i62 , i63.3-i63.5 , i63.8 , i63.9 , and i64 ) , ppv 0.850.98 ( 16 ) ; and heart failure ( icd-9 428.x ; icd-10 i5o ) , ppv 0.84 ( 17 ) . time to event was assessed up to 31 march 2006 for british columbia and to 31 march 2007 for alberta with up to 10 years follow - up ( median 4.0 years ) . patients were censored if they moved out of the province or reached the end of the observation period . we determined age - specific ( reported for the most recent fiscal year , 20032004 ) and age - standardized incidence of diagnosed diabetes for each ethnic and sex group . yearly incidence of diagnosed diabetes ( per 1,000 population ) was calculated using new cases of diabetes for each group as the numerator with the corresponding population count as the denominator for the most recent 5-year time period ( 19992003 ) . annual population counts for each ethnic and sex group were determined by applying the surname algorithms to the annual provincial registry population counts , minimizing denominator bias . we used direct age standardization for each group with the total provincial population in the same fiscal year as the reference group . poisson regression analysis was used to compare incidence rates between ethnic and sex groups and linear regression was used to determine change in incidence over time . cox proportional hazards models were constructed and stratified by sex , with adjustment for province , ses quintile , age in 5-year categories , previous history of ami , heart failure , cerebrovascular disease , peripheral arterial disease , renal impairment , cancer , dementia , chronic pulmonary disease , hypertension , rheumatic disease , peptic ulcer disease , liver disease , hemiplegia , metastatic carcinoma , and aids / hiv . we also conducted sensitivity analyses using the british columbia cohort by additionally adjusting for insulin , metformin , statin , or ace inhibitor prescribing within 5 years of diagnosis using a province - wide prescription drug database ( pharmanet ) only available in british columbia . all analyses were conducted with sas ( version 9.1.3 ) and graphs were plotted using r. this study was approved by the local ethics institutional review boards . < 35 years , 17,602 with gestational diabetes , 199,592 patients without a minimum 3-year period of observation without a diabetes diagnosis , and 43,138 patients without insurance registration within 3 years before diabetes diagnosis , 276,837 remaining patients were identified as having incident cases of diagnosed diabetes ( 15,066 [ 5.4% ] south asian , 17,754 [ 6.4% ] chinese , and 244,017 [ 88.1% ] white patients ) . south asian patients were 4.6 years younger on average than chinese and white patients at diagnosis of diabetes ( table 1 ) . white patients were more likely to have cardiovascular disease and cancer relative to the ethnic groups . baseline characteristics among diabetic patients aged 35 years data are means  sd or n ( % ) . * medication prescribed within 1 year of diagnosis in british columbia patients only . from table 2 , incidence of diagnosed diabetes was higher among men relative to women for all ethnic groups . overall , south asian patients had the highest age - adjusted incidence of diabetes , whereas chinese patients had the lowest ( fig . south asian patients had the highest incidence of diabetes in all young to middle - aged categories . however , after the age of 65 , the incidence of diabetes was highest among white patients . diabetes incidence for white patients and chinese men increased during the observation period but remained stable for south asian patients and chinese women ( fig . age - specific incidence of diagnosed diabetes by ethnicity and sex ( per 1,000 population ) in fiscal year 20032004 * 20032004 population . a : age - adjusted incidence of diagnosed diabetes by ethnicity in women aged 35 years ( 19992003 ) . b : age - adjusted incidence of diagnosed diabetes by ethnicity in men aged 35 years . total mortality was substantially lower in south asian and chinese men and women than in white men and women ( table 3 ) . even after adjustment for baseline characteristics , mortality remained substantially lower in south asian and chinese patients . additional adjustment for use of insulin , metformin , ace inhibitors , or statin therapy in the sensitivity analysis did not materially affect these results . these differences were seen across different age subgroups , within each province , and among those with and without comorbid conditions . age - standardized and -adjusted outcomes by ethnicity in diabetic women and men aged 35 years * hazard ratios are adjusted for age , ses , province , and comorbid conditions including previous history of ami , heart failure , cerebrovascular disease , peripheral arterial disease , renal impairment , cancer , dementia , chronic pulmonary disease , hypertension , connective tissue disease - rheumatic disease , peptic ulcer disease , mild liver disease , paraplegia and hemiplegia , moderate or severe liver disease , metastatic carcinoma , and aids / hiv . south asian and white women had a similar risk of developing macrovascular complications . however , chinese women had a substantially lower risk of ami and heart failure . south asian and chinese men had a lower risk of stroke and heart failure relative to that of white men . chinese men had the lowest risk for ami whereas south asian and white men had a similar risk of ami . from table 2 , incidence of diagnosed diabetes was higher among men relative to women for all ethnic groups . overall , south asian patients had the highest age - adjusted incidence of diabetes , whereas chinese patients had the lowest ( fig . south asian patients had the highest incidence of diabetes in all young to middle - aged categories . however , after the age of 65 , the incidence of diabetes was highest among white patients . diabetes incidence for white patients and chinese men increased during the observation period but remained stable for south asian patients and chinese women ( fig . age - specific incidence of diagnosed diabetes by ethnicity and sex ( per 1,000 population ) in fiscal year 20032004 * 20032004 population . a : age - adjusted incidence of diagnosed diabetes by ethnicity in women aged 35 years ( 19992003 ) . b : age - adjusted incidence of diagnosed diabetes by ethnicity in men aged 35 years . total mortality was substantially lower in south asian and chinese men and women than in white men and women ( table 3 ) . even after adjustment for baseline characteristics , mortality remained substantially lower in south asian and chinese patients . additional adjustment for use of insulin , metformin , ace inhibitors , or statin therapy in the sensitivity analysis did not materially affect these results . these differences were seen across different age subgroups , within each province , and among those with and without comorbid conditions . age - standardized and -adjusted outcomes by ethnicity in diabetic women and men aged 35 years * hazard ratios are adjusted for age , ses , province , and comorbid conditions including previous history of ami , heart failure , cerebrovascular disease , peripheral arterial disease , renal impairment , cancer , dementia , chronic pulmonary disease , hypertension , connective tissue disease - rheumatic disease , peptic ulcer disease , mild liver disease , paraplegia and hemiplegia , moderate or severe liver disease , metastatic carcinoma , and aids / hiv . south asian and white women had a similar risk of developing macrovascular complications . however , chinese women had a substantially lower risk of ami and heart failure . south asian and chinese men had a lower risk of stroke and heart failure relative to that of white men . chinese men had the lowest risk for ami whereas south asian and white men had a similar risk of ami . south asian patients had the highest incidence of diagnosed diabetes , whereas chinese patients had the lowest incidence . mortality was also lower for south asian and chinese patients compared with that for white patients with newly diagnosed diabetes , for both men and women . however , macrovascular complications varied by ethnicity and sex . there is a disproportionately high rate of new cases of diabetes among young to middle - aged , south asian patients . the age- and sex - specific incidence pattern of diabetes among white patients is also consistent with general population incidence rates ( 8) . the observed lower incidence of diabetes in chinese patients contrasts with that in a small study reporting a similar incidence between chinese and other patients in the u.s . diabetes guidelines generally recommend initial screening for diabetes at age 45 years , although a younger threshold is recommended for patients of asian descent . it is also not known whether early surveillance would benefit other asian groups ( e.g. , chinese ) . this study identified an alarmingly high incidence of diabetes in south asian patients , particularly in men aged 3544 years , indicating that screening as early as 35 years may be warranted . our findings also suggest that chinese patients do not necessarily share this early proclivity for developing diabetes . despite a greater predilection for developing diabetes , we found a paradoxically lower mortality among south asians than among white patients . although south asian patients were considerably younger and both south asian and chinese patients possessed fewer comorbid conditions at the onset of diabetes , the mortality benefit persisted after adjustment for these differences . our findings are consistent with results from several smaller studies of diabetic patients ( 19,20 ) , and general population mortality rates also indicate lower all - cause mortality for south asian and chinese patients compared with white patients living in north america ( 21 ) . our results , however , contrast with those for the southall diabetes survey cohort , which reported a nonsignificant trend toward increased mortality in south asian patients compared with their white counterparts using prevalent rather than incident cases ( 22 ) . however , mortality rates for all groups were substantially higher compared with general population mortality rates for chinese , south asian , and white patients living in north america ( 21 ) . this observation suggests that the presence of diabetes confers a greater risk of death regardless of ethnicity . the reasons for the ethnic and sex differences in mortality and macrovascular complications of diabetes are unclear , and we can speculate on possible mechanisms . south asian and chinese patients , particularly men , may have their diabetes diagnosed earlier along the course of disease and may receive more aggressive care . however , even after we adjusted for metformin , statin , and ace inhibitor prescribing , the mortality benefit in south asian and chinese patients persisted . alternatively , some ethnic patients may not have accessed medical care and were therefore not included in the study population . these individuals with undiagnosed diabetes may be more likely to experience early mortality . however , a national survey in canada found that visible minority and white patients reported a similarly high frequency of physician visits ( 23 ) . chinese and south asian patients have lower rates of smoking and bmi , potentially contributing to their survival advantage . however , these differences are unlikely to account for all the benefit . in a u.s . study , despite adjustment for these differences , a lower risk of ami , stroke , and heart failure was identified in asian patients with newly diagnosed diabetes ( 24 ) ; however , south asian and chinese subgroups were not analyzed separately . in our analysis , white patients had higher rates of cardiovascular complications and therefore may have higher rates of cardiovascular death . consistent with a general population study , white patients may also have higher rates of noncardiovascular death , including deaths due to cancer ( 21 ) , collectively contributing to their higher all - cause mortality . . this observation may reflect fewer differences in diabetes management among women of different ethnic backgrounds . a study of 9,833 diabetic patients identified similar service delivery and intermediate outcomes including a1c levels and systolic blood pressure among scottish and south asian women ( 25 ) . the lower rates of cardiovascular complications in the ethnic groups may reflect possible differences in chronic disease management including increased adherence to medication and strong family supports . some of these influences such as family support and care - giving may also differ by sex within cultural groups . the strengths of this study include the use of population - based data for a large , ethnically diverse area using coding algorithms extensively validated against physician diagnosis in the same geographic region . however , there are several limitations . first , we used surname algorithms alone to categorize ethnicity rather than self - report . although the specificities of these algorithms were high , there is potential for some misclassification of ethnic categories that would underestimate differences among ethnic categories . second , we could not differentiate type 1 and type 2 diabetes , although from our sensitivity analysis in british columbia , < 3% of patients received insulin within 1 year of diabetes diagnosis . third , we were only able to identify physician - diagnosed diabetes , underestimating the true incidence of diabetes . fourth , observational studies are susceptible to bias from residual confounding including confounding by age . we were unable to control for differences in smoking , bmi , visceral fat , and diabetes control . we did not have information on year of immigration , but because the majority of immigration to canada by these ethnic groups has occurred in the past 25 years ( 6 ) , this population would largely be composed of first - generation immigrants . finally , we used broad ethnic categories , and there is likely some heterogeneity among smaller subgroups within each ethnic category . in summary , diabetes incidence and outcomes south asian patients have a significantly higher incidence of physician - diagnosed diabetes that is concentrated at young and middle ages , whereas chinese patients do not . these results may have implications for screening and timing of culturally sensitive interventions to reduce this epidemic . we also observed a paradoxical finding that despite a high incidence of diabetes , mortality was lower in south asian patients than in the general diabetic population and macrovascular complication occurrence further varied by sex . further studies are needed to confirm this paradoxical finding and elucidate underlying mechanisms for differences in diabetes risk and outcomes by ethnicity and sex .
objectivediabetes guidelines recommend aggressive screening for type 2 diabetes in asian patients because they are considered to have a higher risk of developing diabetes and potentially worse prognosis . 
 we determined incidence of diabetes and risk of death or macrovascular complications by sex among major asian subgroups , south asian and chinese , and white patients with newly diagnosed diabetes.research design and methodsusing population - based administrative data from british columbia and alberta , canada ( 19971998 to 20062007 ) , we identified patients with newly diagnosed diabetes aged 35 years and followed them for up to 10 years for death , acute myocardial infarction , stroke , or hospitalization for heart failure . 
 ethnicity was determined using validated surname algorithms.resultsthere were 15,066 south asian , 17,754 chinese , and 244,017 white patients with newly diagnosed diabetes . 
 chinese women and men had the lowest incidence of diabetes relative to that of white or south asian patients , who had the highest incidence . 
 mortality in those with newly diagnosed diabetes was lower in south asian ( hazard ratio 0.69 [ 95% ci 0.620.76 ] , p < 0.001 ) and chinese patients ( 0.69 [ 0.630.74 ] , p < 0.001 ) then in white patients . 
 risk of acute myocardial infarction , stroke , or heart failure was similar or lower in the ethnic groups relative to that of white patients and varied by sex.conclusionsthe incidence of diagnosed diabetes varies significantly among ethnic groups . 
 mortality was substantially lower in south asian and chinese patients with newly diagnosed diabetes than in white patients .