Niina Lammi

Seasonal variation of diagnosis of Type 1 diabetes mellitus in children worldwide

Aims  To determine if there is a worldwide seasonal pattern in the clinical onset of Type 1 diabetes.

Marked temporal increase in the incidence of type 1 and type 2 diabetes among young adults in Finland.

To the Editor: Previously we reported data on trends in the incidence of type 1 and type 2 diabetes in Finnish young adults aged 15–39 years during 1992–1996 [1] and found a 7.9% average annual increase in the incidence of type 2 diabetes. This rising trend needed to be confirmed during a longer period of follow-up, and therefore we extended the study until the year 2001. The collection of data and the classification of patients with diabetes ascertained during 1992 to 1996 have been described in detail previously [1]. The information on new diagnoses of diabetes in the age group of 15–39 years between 1997 and 2001 were obtained from three nationwide registers in Finland. The first register was the Drug Prescription Register of the Social Insurance Institute, which comprises ATC-DDD codes [2] on all prescriptions since 1994, and for this study all the class A10 drugs (drugs used in diabetes) were reviewed. The second register was the Drug Reimbursement Register of the Social Insurance Institute, which comprises information on persons entitled to free-of-charge medication for diabetes. The entitlement is given in response to an application that includes a detailed medical statement prepared by the treating physician. The third register was the Hospital Discharge Register, maintained by the National Research and Development Centre for Welfare and Health, which includes the treating physician’s diagnoses in ICD-10 codes [3]. Data from these registers were linked using the unique personal identification number assigned to every Finnish resident. The date of the first entry in any of these registers was set as the date of the diagnosis of diabetes. The patient had to be recorded in at least two of these registers to be included. A patient was classified as having type 1 diabetes if two of the following three criteria were fulfilled: (1) an ICD-10 diagnosis referring only to type 1 diabetes; (2) permanent entitlement to free-of-charge medication; (3) only insulin was administered immediately at diagnosis and continued until the end of the year 2004. A patient was classified as having type 2 diabetes if two of the following three criteria were fulfilled: (1) an ICD-10 diagnosis referring only to type 2 diabetes; (2) permanent or temporary entitlement to free-of-charge medication; (3) only oral glucose-lowering agents had been prescribed. For patients who could not be reliably classified with this method, the application records for free-of-charge medication were acquired from the Social Insurance Institute and reviewed in order to assign the type of diabetes (n=791). Information on patients with no entitlement to free-of-charge medication (n=563) was reviewed, and most were classified as having gestational diabetes, as expected (persons with gestational diabetes are not entitled to free-of-charge medication). Patients who were impossible to classify as having type 1 or type 2 diabetes were classified as having an undefined type of diabetes. Diabetologia (2008) 51:897–899 DOI 10.1007/s00125-008-0952-9

Age at Onset of Type 1 Diabetes in Parents and Recurrence Risk in Offspring

OBJECTIVE Our aim was to study the recurrence risk of type 1 diabetes in the offspring of parents with adult-onset (15–39 years) type 1 diabetes and to evaluate the transmission of diabetes within a continuum of parental age at onset of diabetes from childhood to adulthood. RESEARCH DESIGN AND METHODS Diabetes status of all offspring (n = 9,636) in two Finnish cohorts of parents with type 1 diabetes was defined until the end of year 2007. Cumulative incidences of type 1 diabetes among the offspring were estimated, and several factors contributing to the risk were assessed. RESULTS During 137,455 person-years, a total of 413 offspring were diagnosed with type 1 diabetes. The cumulative incidence by 20 years was 4.0% (95% CI 3.1–4.8) for the offspring of parents with adult-onset diabetes. The risk was equal according to the sex of the parents. The cumulative incidence decreased in parallel with the increase in age at onset of diabetes in the fathers. In the offspring of diabetic mothers, the risk was equal regardless of the age at onset of diabetes. However, the reduced risk in the maternal offspring was most pronounced in the daughters of the mothers with a diagnosis age <10 years. CONCLUSIONS Type 1 diabetes transmission ratio distortion is strongly related to the sex and age at onset of diabetes in the diabetic parents.

Perinatal risk factors in young adult-onset type 1 and type 2 diabetes – a population-based case-control study

Objective. To examine the effects of the size of the mother and the newborn, including placental weight and gestational age at delivery, on the risk for young adult‐onset type 1 diabetes (T1DM) and type 2 diabetes (T2DM). Design. Case‐control study. Setting. Finland. Population. Subjects with T1DM and T2DM aged 15–39 at diagnosis between the years 1992 and 1996. The number of case‐control pairs was 858 for T1DM and 355 for T2DM. Methods. Diabetic subjects were identified from the Finnish national healthcare registers and reports from diabetes nurses. Control subjects were obtained from the population register. Data on perinatal factors were obtained from the original healthcare records. The odds ratios (ORs) for both types of diabetes were estimated using conditional logistic regression. Results. The risk for early‐onset T2DM decreased with increasing birthweight until 4.2 kg (OR 0.49 (95% confidence interval 0.37–0.66) per 1 kg), but with birthweight above 4.2 kg the risk increased (OR 4.8 (1.3–17.6) per 1 kg). The risk for T2DM decreased also with increasing birth length (OR 0.88 (0.81–0.95) per 1 cm), body mass index at birth (OR 0.81 (0.73–0.90) per 1 kg/m2), and placental weight (OR 0.77 (0.61–0.98) per 100 g). The latter was not significant when adjusted for birthweight. The examined perinatal factors did not affect the risk for T1DM in young adults. Conclusions. Birth size significantly affects the risk for T2DM diagnosed in young adulthood but no evidence was found of an association between late‐onset T1DM and perinatal factors.

Temporal variation in case fatality of acute myocardial infarction in Finland

Background. Previous studies have suggested that seasonal variation and weather conditions have an influence on the incidence and mortality of acute myocardial infarction (AMI). The influence of these factors on AMI case fatality is less studied. Aims. The aim of this study was to examine the temporal variation of AMI case fatality and the effect of daily weather conditions on it. Methods. We analysed death registry and hospital discharge data from all men and women (n=7328) with their first AMI occurrence in the seven largest cities in Finland in the years 1983, 1988, and 1993, aged 25 to 74 years. Results. The mean annual 28-day case fatality was 44%. We found significant weekly and monthly variation of case fatality (P<0.001). The December holiday season had the highest case fatality throughout the year in women and men aged 65–74 years (P<0.05). The highest weekly case fatality was on Sundays; it differed significantly from the rest of the weekdays only for the oldest age-group (64–74) (P<0.01). Conclusions. There is significant weekly and monthly variation in case fatality of AMI. The highest case fatality risk for AMI is during the Christmas season and on Sundays. Weather conditions were not found to have an effect on the case fatality.

Perinatal Risk Factors in Young Adult-Onset Type 1 and Type 2 Diabetes―A Population-Based Case-Control Study

The risk of type 2 diabetes (T2DM) and related conditions such as hypertension and coronary heart disease is increased in low birth weight infants, and may be increased in infants with abnormally high birth weights. Conversely, there appears to be only a weak association between type 1 diabetes (T1DM) and either low or high birth weight. With the increasing prevalence of T2DM in the young adult population, there is a need to assess the role of birth weight and other perinatal factors on the risk of adult onset type 2 disease. This case-control study assessed the effects of birth weight, maternal weight, gestational age at delivery, placental size, and other perinatal factors on the incidence of T1DM and T2DM in young Finnish adults aged 15 to 39 years who were diagnosed with diabetes between 1992 and 1996. The study subjects included 858 case-control pairs of T1DM and 355 case-control pairs of T2DM. All cases of diabetes were identified from the Finnish national healthcare registers and controls were randomly chosen from the National Population Register. Data on perinatal factors (birth weight, birth length, placental weight, gestational age, and maternal body size) were collected from the original healthcare records. Odds ratios (ORs) for T1DM and T2DM were analyzed separately using conditional logistic regression. The risk of young adult-onset T2DM decreased with increasing birth weight until 4.2 kg and began to rise with birth weights >4.2 kg; the OR for T2DM in infants up to 4.2 kg was 0.49 (95% confidence interval [CI], 0.37-0.66) per 1 kg (P 4.2 kg was 4.8 (95% CI, 1.32-17.62) per 1 kg (P = 0.018). There was decreased risk of T2DM with increasing birth length (OR, 0.88; 95% CI, 0.81-0.95) per 1 cm (P < 0.01), birth body mass index (OR, 0.81; 95% CI, 0.73-0.90) per 1 kg/m 2 (P < 0.01), and placental weight (OR, 0.77; 95% CI, 0.61-0.98) per 100 gm (P < 0.03). The difference in placental weight was not significant after adjustment for birth weight. None of the examined perinatal factors had an effect on the risk of T1DM with onset between 15 and 39 years. These findings indicate that birth weight has a significant effect on the risk of T2DM in young adults. No association, however, was found between perinatal factors and risk of adult-onset T1DM.