Mortality trends in type 1 diabetes: a multicountry analysis of six population-based cohorts.

AIMS/HYPOTHESIS: Mortality has declined in people with type 1 diabetes in recent decades. We examined how the pattern of decline differs by country, age and sex, and how mortality trends in type 1 diabetes relate to trends in general population mortality. METHODS: We assembled aggregate data on all-cause mortality during the period 2000-2016 in people with type 1 diabetes aged 0-79 years from Australia, Denmark, Latvia, Scotland, Spain (Catalonia) and the USA (Kaiser Permanente Northwest). Data were obtained from administrative sources, health insurance records and registries. All-cause mortality rates in people with type 1 diabetes, and standardised mortality ratios (SMRs) comparing type 1 diabetes with the non-diabetic population, were modelled using Poisson regression, with age and calendar time as quantitative variables, describing the effects using restricted cubic splines with six knots for age and calendar time. Mortality rates were standardised to the age distribution of the aggregate population with type 1 diabetes. RESULTS: All six data sources showed a decline in age- and sex-standardised all-cause mortality rates in people with type 1 diabetes from 2000 to 2016 (or a subset thereof), with annual changes in mortality rates ranging from -2.1% (95% CI -2.8%, -1.3%) to -5.8% (95% CI -6.5%, -5.1%). All-cause mortality was higher for male individuals and for older individuals, but the rate of decline in mortality was generally unaffected by sex or age. SMR was higher in female individuals than male individuals, and appeared to peak at ages 40-70 years. SMR declined over time in Denmark, Scotland and Spain, while remaining stable in the other three data sources. CONCLUSIONS/INTERPRETATION: All-cause mortality in people with type 1 diabetes has declined in recent years in most included populations, but improvements in mortality relative to the non-diabetic population are less consistent.

Decreasing incidence of pharmacologically and non-pharmacologically treated type 2 diabetes in Norway: a nationwide study.

AIMS/HYPOTHESIS: This study aimed to examine recent time trends in the incidence and prevalence of type 2 diabetes in Norway. METHODS: In this Norwegian nationwide cohort study, we linked data from national registries with prospectively collected data on diabetes medication and diabetes diagnoses for all residents in Norway aged 30 to 89 years (>3.2 million people). We analysed trends in incidence and prevalence of type 2 diabetes from 2009 to 2014 by type of treatment, sex, age, education level and place of birth. RESULTS: During 15,463,691 person-years of follow-up from 2009 to 2014, we identified 75,496 individuals with new-onset type 2 diabetes. Of these, 36,334 (48%) were treated with blood-glucose-lowering drugs within 6 months of diagnosis. A low education level and being born in Asia, Africa or South America were significant risk factors for incident type 2 diabetes. While the prevalence of type 2 diabetes increased from 4.9% to 6.1% during the study period, the incidence decreased significantly from 609 cases per 100,000 person-years in 2009 to 398 cases per 100,000 in 2014, an annual reduction of 10.1% (95% CI -10.5, -9.6). A declining incidence was seen for both pharmacologically and non-pharmacologically treated type 2 diabetes, and in all subgroups defined by sex, age group, education level and place of birth. CONCLUSIONS/INTERPRETATIONS: This nationwide study shows that, despite a decreasing incidence of type 2 diabetes in Norway, the prevalence continues to rise, probably due to diagnosis at a younger age and increased longevity.

Pandemic influenza and subsequent risk of type 1 diabetes: a nationwide cohort study.

AIMS/HYPOTHESIS: Case reports have linked influenza infections to the development of type 1 diabetes. We investigated whether pandemic and seasonal influenza infections were associated with subsequent increased risk of type 1 diabetes. METHODS: In this population-based registry study, we linked individual-level data from national health registries for the entire Norwegian population under the age of 30 years for the years 2006-2014 (2.5 million individuals). Data were obtained from the National Registry (population data), the Norwegian Patient Registry (data on inpatient and outpatient specialist care), the Primary Care Database, the Norwegian Prescription Database and the Norwegian Surveillance System for Communicable Diseases. Pandemic influenza was defined as either a clinical influenza diagnosis during the main pandemic period or a laboratory-confirmed test. Seasonal influenza was defined by a clinical diagnosis of influenza between 2006 and 2014. We used Cox regression to estimate HRs for new-onset type 1 diabetes after an influenza infection, adjusted for year of birth, sex, place of birth and education. RESULTS: The adjusted HR for type 1 diabetes after pandemic influenza infection was 1.19 (95% CI 0.97, 1.46). In the subgroup with laboratory-confirmed influenza A (H1N1), influenza was associated with a twofold higher risk of subsequent type 1 diabetes before age 30 years (adjusted HR: 2.26, 95% CI 1.51, 3.38). CONCLUSIONS/INTERPRETATION: Overall, we could not demonstrate a clear association between clinically reported pandemic influenza infection and incident type 1 diabetes. However, we found a twofold excess of incident diabetes in the subgroup with laboratory-confirmed pandemic influenza A (H1N1).