Residual beta-cell function and male/female ratio are higher in incident young adults than in children: the registry of type 1 diabetes of the province of Turin, Italy, 1984-2000

The Incidence of Adult-Onset Type 1 Diabetes: A Systematic Review From 32 Countries and Regions

BACKGROUND

The epidemiology of adult-onset type 1 diabetes (T1D) incidence is not well-characterized due to the historic focus on T1D as a childhood-onset disease.

PURPOSE

We assess the incidence of adult-onset (≥20 years) T1D, by country, from available data.

DATA SOURCES

A systematic review of MEDLINE, Embase, and the gray literature, through 11 May 2021, was undertaken.

STUDY SELECTION

We included all population-based studies reporting on adult-onset T1D incidence and published from 1990 onward in English.

DATA EXTRACTION

With the search we identified 1,374 references of which 46 were included for data extraction. Estimates of annual T1D incidence were allocated into broad age categories (20-39, 40-59, ≥60, or ≥20 years) as appropriate.

DATA SYNTHESIS

Overall, we observed the following patterns: 1) there is a paucity of data, particularly in low- and middle-income countries; 2) the incidence of adult-onset T1D is lowest in Asian and highest in Nordic countries; 3) adult-onset T1D is higher in men versus women; 4) it is unclear whether adult-onset T1D incidence declines with increasing age; and 5) it is unclear whether incidence of adult-onset T1D has changed over time.

LIMITATIONS

Results are generalizable to high-income countries, and misclassification of diabetes type cannot be ruled out.

CONCLUSIONS

From available data, this systematic review suggests that the incidence of T1D in adulthood is substantial and highlights the pressing need to better distinguish T1D from T2D in adults so that we may better assess and respond to the true burden of T1D in adults.

Clinical and demographic features among patients with type 1 diabetes mellitus in Henan, China

BACKGROUND

The hallmark of type 1 diabetes (T1D) is an absolute lack of insulin. However, many studies showed a tendency to heterogeneity in TID. We aimed to investigate the demographic and clinical characteristics in T1D and the differences in young-onset and adult-onset patients.

METHODS

This retrospective study was conducted among 1943 patients with clinically diagnosed T1D. Medical records on patients' demographics, anthropometric measurements, and clinical manifestation were collected. According to the age at onset, the newly diagnosed patients were divided into the young-onset group (< 18 years, 234 patients, mean age 11 years) and adult-onset group (≥ 18 years, 219 patients, mean age 27 years). Pancreatic β-cell function was assessed by fasting C-peptide (FCP) and 2-h C-peptide (2-h CP).

RESULTS

The median age of patients at disease onset was 22 years. The median duration of patients was 3 years. The overall median glycated hemoglobin (HbA1c) value was 10.3 % [89(mmol/mol)]. The prevalence of diabetic retinopathy was 25.1 %. The overall rate of DKA at onset in the new-onset patients was 59.6 %. The frequency of overall dyslipidemia was 37.8 %. The most frequent dyslipidemia was low high-density lipoprotein-cholesterol (HDL) (29 %). The proportion of patients with anti-glutamic acid decarboxylase (GADA), insulin antibody (IAA) and islet cell antibody (ICA) were 28.1 %, 6.4 % and 21.6 %, respectively. The mean HbA1c showed a downward trend with age. Increasing or decreasing trends of overweight and obesity in this population during the period 2012 to 2018 was not found. Compared with young-onset T1D, adult-onset patients comprised better islet function (FCP: 0.4 vs. 0.3 ng/ml, P < 0.001; 2-h CP: 0.9 vs. 0.7 ng/ml P < 0.001, respectively) and glycemic control [12.9 % (117mmol/mol) vs. 11.7 % (104mmol/mol), P < 0.001], higher prevalence of diabetes condition in the male gender (64.4 % vs. 51.3 %, P = 0.006), higher proportion of obesity or overweight (24.6 % vs. 9.5 %, P = 0.002), higher frequency of GADA (33.7 % vs. 23.3 %, P = 0.025), and lower frequency of diabetic ketoacidosis at disease onset (64.5 % vs. 43.5 %, P < 0.001).

CONCLUSIONS

This population was characterized by poor overall blood glucose control, high prevalence of DKA, dyslipidemia and diabetic retinopathy, and low prevalence of islet-related antibodies, and overweight or obesity. Adult-onset patients with T1D were not uncommon and had better clinical manifestations than young-onset patients. Any findings related to body mass index (BMI) and autoantibodies should be considered strictly exploratory due to excessive missing data.

Surrogate markers and predictors of endogenous insulin secretion in children and adolescents with type 1 diabetes

BACKGROUND

No studies have examined endogenous insulin secretion in pediatric patients with type 1 diabetes in China using the gold-standard mixed-meal tolerance test. Because the latter is labor-intensive, we examined simpler surrogate markers of endogenous insulin secretion in Chinese youth, as previously reported for a European population.

METHODS

Participants were 57 children and adolescents with type 1 diabetes aged 4.4-16.8 years (56% females). We performed 120-minute mixed-meal tolerance tests with serum C-peptide (CP) measurements every 30 minutes. Severe insulin deficiency (SID) was defined as CP peak < 0.2 nmol/L. Urine CP and creatinine levels were measured at 0 and 120 minutes.

RESULTS

Twenty-five (44%) patients had SID. Fasting CP levels missed one case (96% sensitivity) with no false positives (100% specificity). While the 120-minute urine CP/creatinine had 100% sensitivity, it yielded markedly lower specificity (63%). Every 1-year increase in diabetes duration and 1-year decrease in age at diagnosis were associated with 37% (P < 0.001) and 20% (P = 0.005) reductions in serum CP area-under-the-curve, respectively. Thus, 86% of children aged < 5 years had SID compared to none among patients aged ≥ 11 years.

CONCLUSIONS

Simple fasting CP measurements could be used to detect most SID cases in Chinese youth with type 1 diabetes. Fasting CP is a far more reliable measure of endogenous insulin secretion than the more commonly used insulin dose. Therefore, it could more precisely determine insulin secretory capacity to target those who could benefit, if treatments to preserve residual insulin secretion are developed.

Adult-onset type 1 diabetic patients with less severe clinical manifestation have less risk DR-DQ genotypes than childhood-onset patients

BACKGROUND

The aim of this study was to investigate differences in clinical features and HLA genotypes between adult-onset and childhood-onset patients with type 1 diabetes in a Chinese population.

MATERIALS AND METHODS

This study enrolled 716 Han Chinese patients with type 1 diabetes from Guangdong (258 childhood-onset and 458 adult-onset) to compare their clinical features. Of them 214 patients with classical type 1 diabetes (100 childhood-onset and 114 adult-onset) were selected for HLA DR and DQ genotyping by next-generation sequencing.

RESULTS

Adult-onset patients were characterized by longer duration of symptoms before diagnosis, lower frequency of DKA at disease onset, less frequent autoantibody positivity, higher serum C-peptide concentrations, and better glycemic control. These findings were replicated in the restricted cohort of 214 patients with classical type 1 diabetes. Compared with childhood-onset patients, adult-onset patients had a lower frequency of the DR9 haplotype, as well as lower frequency of high-risk DR3/DR4 and DR3/DR9 genotypes, but higher frequency of DR3/DR3 genotype and DR3/X, DR4/X or DR9/X (X, non-risk) genotypes.

CONCLUSIONS

Adult-onset type 1 diabetic patients with susceptible haplotypes (DR3, DR4 or DR9) were more likely to carry protective DR-DQ haplotypes than childhood-onset patients, which suggested the association between less risk DR-DQ genotypes and the less severe clinical manifestation in adult-onset patients.

Incidence trend of type 1 diabetes mellitus in Serbia

BACKGROUND

The incidence of type 1 diabetes mellitus (T1DM) increased worldwide. The objective of the paper was to compare the incidence trend of T1DM in children and adolescents aged 0-19 and in adults under 30 years of age in Serbia from 2006 to 2017. Additional aim was to compare incidence rates of T1DM and type 2 diabetes mellitus (T2DM) among adults aged 20-24 and 25-29 years of age.

METHODS

Trends and annual percentage change (APC) of the incidence rate with corresponding 95% confidence intervals (CI) were calculated by Joinpoint Regression Analyses.

RESULTS

We found a significant increase of incidence in children aged 5-9 with the APC of 5.7% (95%CI: 2.3-9.1), and in children aged 10-14 with the APC of 2.1% (95%CI: 0.6-3.6). A significant decrease of incidence was determined in adolescents aged 15-19 with the APC -4.9% (95%CI: - 8.9 to - 0.7) and in adults aged 25-29 with the APC -7.3% (95%CI: - 12.5 to - 1.8).

CONCLUSION

The increase of incidence in children aged 0-14 and its decrease after 15 years of age showed that T1DM is predominantly a metabolic disease of children in Serbia. A significant increase in incidence was recorded in two age groups, namely 5-9 and 10-14 years of age. The highest increase was in children aged 5-9 and the highest incidence rate was in children aged 10-14. An insignificant increasing of T2DM incidence was observed in young adults aged 25-29. The increase in incidence rates in children, but not in young adults, suggests that the precipitating factors of children-onset disease may differ from those of adult-onset T1DM.

High Proportion of Adult Cases and Prevalence of Metabolic Syndrome in Type 1 Diabetes Mellitus Population in Korea: A Nationwide Study

BACKGROUND

The prevalence and incidence of type 1 diabetes mellitus (T1DM) in all age groups and the prevalence of metabolic syndrome in patients with T1DM in Korea were estimated.

METHODS

The incidence and prevalence of T1DM between 2007 and 2013 were calculated using the Korean National Health Insurance Service (NHIS) datasets of claims. Clinical characteristics and prevalence of metabolic syndrome in individuals with T1DM between 2009 and 2013 were determined using the database of NHIS preventive health checkups.

RESULTS

The prevalence of T1DM in Korea between 2007 and 2013 was 0.041% to 0.047%. The annual incidence rate of T1DM in Korea in 2007 to 2013 was 2.73 to 5.02/100,000 people. Although the incidence rate of typical T1DM was highest in teenagers, it remained steady in adults over 30 years of age. In contrast, the incidence rate of atypical T1DM in 2013 was higher in people aged 40 years or older than in younger age groups. Age- and sex-adjusted prevalence of metabolic syndrome in patients with T1DM was 51.65% to 55.06% between 2009 and 2013.

CONCLUSION

T1DM may be more common in Korean adults than previously believed. Metabolic syndrome may be a frequent finding in individuals with T1DM in Korea.

Incidence of type 1 diabetes in age groups above 15 years: facts, hypothesis and prospects for future epidemiologic research

Although onset of type 1 diabetes can occur in adulthood, epidemiological data are scarce, limiting our potential to identify unknown determinants of the disease. Paucity of registries expanding the recruitment of incident cases up to adulthood, atypical clinical features of type 1 diabetes at onset, misclassification of type 1 as type 2 diabetes and little use of markers of β-cell autoimmunity represents major obstacles in studying the risk of type 1 diabetes in adults. New strategies in study design, data collection and analyses may overcome these problems in the future. Population-based surveys and registries including adulthood; use of etiological rather than clinical criteria to define type 1 diabetes; availability of electronic health records as prescription data sources to avoid missing data; and application of proper statistical methods will be instrumental to gain better insight on the epidemiology and natural history of the disease.

Early life socioeconomic indicators and risk of type 1 diabetes in children and young adults

OBJECTIVE

To examine the potential role of 2 early-life socioeconomic indicators, parental education, and crowding index, on risk of type 1 diabetes (T1DM) in patients up to age 29 years to test heterogeneity by age at onset according to the hygiene hypothesis.

STUDY DESIGN

The study base was 330 950 individuals born from 1967 to 2006 who resided in the city of Turin at any time between 1984 and 2007. Data on their early life socioeconomic position were derived from the Turin Longitudinal Study; 414 incident cases of T1DM up to age 29 years were derived from the Turin T1DM registry.

RESULTS

Socioeconomic indicators had opposing effects on risk of T1DM in different age at onset subgroups. In a Poisson regression model that included both socioeconomic indicators, there was a 3-fold greater risk of T1DM (relative risk 2.91, 95% CI 0.99-8.56) in children age 0-3 years at diagnosis living in crowded houses. In the 4- to 14-year subgroup, a low parental educational level had a protective effect (relative risk 0.50, 95% CI 0.29-0.84), and the effect of crowding nearly disappeared. In the 15- to 29-year subgroup, neither crowding nor parental educational level was clearly associated with the incidence of T1DM.

CONCLUSIONS

We provide evidence of heterogeneity by age at onset of the association between early-life socioeconomic indicators and the risk of T1DM. This finding is consistent with the hypothesis that infectious agents in the perinatal period may increase the risk, whereas in the following years they may become protective factors (hygiene hypothesis).

C-peptide response and HLA genotypes in subjects with recent-onset type 1 diabetes after immunotherapy with DiaPep277: an exploratory study

OBJECTIVE

To investigate whether lower risk HLA class II genotypes would influence the efficacy of DiaPep277 therapy in protecting β-cell function evaluated by C-peptide secretion in recent-onset type 1 diabetic subjects.

RESEARCH DESIGN AND METHODS

Data were collected from type 1 diabetic subjects enrolled in multicenter phase II studies with a randomized, double-blind, and placebo-controlled design in whom fasting and stimulated C-peptide levels were measured. HLA genotypes were classified in high, moderate, and low risk categories.

RESULTS

A total of 146 subjects (aged 4.3 to 58.5 years) were enrolled, including 76 children (<18 years old) and 70 adults. At baseline, there was a significant increase in fasting, maximal, and area under the curve (AUC) C-peptide from high to moderate and low risk HLA genotypes in adults (P for trend <0.04) but not in children. Children showed a decrease of the three parameters over time regardless of therapy and HLA genotype. DiaPep277-treated adults with low risk genotype had significantly higher maximal and AUC C-peptide versus placebo at 12 months (0.04 ± 0.07 vs. -0.28 ± 0.09 nmol/L, P < 0.01, and 0.53 ± 1.3 vs. -4.59 ± 1.5 nmol/L, P < 0.05, respectively). In the moderate risk genotype group, Δmaximal and AUC C-peptide values were significantly higher in DiaPep277-treated versus placebo-treated patients (P < 0.01 and P < 0.05, respectively).

CONCLUSIONS

This exploratory study demonstrates that type 1 diabetic adults with low and moderate risk HLA genotypes benefit the most from intervention with DiaPep277; the only subgroup with an increase of C-peptide at 12 months after diagnosis was the low risk DiaPep277-treated subgroup.

Practical steps to improving the management of type 1 diabetes: recommendations from the Global Partnership for Effective Diabetes Management

The Diabetes Control and Complications Trial (DCCT) led to considerable improvements in the management of type 1 diabetes, with the wider adoption of intensive insulin therapy to reduce the risk of complications. However, a large gap between evidence and practice remains, as recently shown by the Pittsburgh Epidemiology of Diabetes Complications (EDC) study, in which 30-year rates of microvascular complications in the 'real world' EDC patients were twice that of DCCT patients who received intensive insulin therapy. This gap may be attributed to the many challenges that patients and practitioners face in the day-to-day management of the disease. These barriers include reaching glycaemic goals, overcoming the reality and fear of hypoglycaemia, and appropriate insulin therapy and dose adjustment. As practitioners, the question remains: how do we help patients with type 1 diabetes manage glycaemia while overcoming barriers? In this article, the Global Partnership for Effective Diabetes Management provides practical recommendations to help improve the care of patients with type 1 diabetes.

An obese patient with slowly progressive type 1 diabetes diagnosed by ketoacidosis

The patient was a 69-year-old woman with a family history of type 2 diabetes. Her body mass index was 31.5. She was diagnosed as type 2 diabetes 32 years previously, and treated with insulin for 8 years. She had no episode of weight loss. She was hospitalized with diabetic ketoacidosis for the first time. Her GAD antibodies were not detected. However, ICA antibodies and insulin antibodies were positively detected. She was diagnosed with type 1 diabetes. Interestingly, her diabetes state was controlled to the same level after recovery from ketoacidosis.

Short-term mortality risk in children and young adults with type 1 diabetes: the population-based Registry of the Province of Turin, Italy

Short-term mortality risk in young diabetic people is an indicator of quality of care. We assessed this in the Italian incident population-based registry of Turin. The study base included 1210 incident cases (n=677 aged 0-14 years and n=533 aged 15-29 years) with diabetes, onset period 1974-2000 in the Province of Turin, Italy. The relevant timescale for analysis was the time since the onset of diabetes to death, or till 31 December 2003. Standardized mortality ratio (SMR) for all-cause mortality was computed using the Italian population as a standard, by 5 years, age group, sex, and calendar period. Mean attained age of the incident cohort was 29.7 years (range 5.2-49.7 years). During a mean follow-up period of 15.8 years (range 2.0-29.9 years), there were 19 deaths in 15,967. Nine person-years of observation (n=9.5 expected deaths), giving an all-cause mortality rate of 1.19/1000 person-years (95% CI 0.76-1.87) and an SMR of 1.96 (1.25-3.08). In no cases did death occur at the onset of diabetes or in childhood. Out of 19 deaths, 9 were diabetes related (n=6 coma and n=3 end-stage renal disease). In Cox regression analysis, the hazard ratio (HR) was higher in adult-onset than in childhood-onset diabetes (HR=3.90, 95% CI 1.14-13.39), independently of calendar period and gender. (1) Children and young adults with type 1 diabetes experienced a two-fold higher short-term mortality risk than Italian people of similar age and sex and (2) the risk was higher in adult-onset than in childhood-onset diabetes. The quality of diabetes care should be improved to prevent early deaths.

Fasting plasma C-peptide and micro- and macrovascular complications in a large clinic-based cohort of type 1 diabetic patients

OBJECTIVE

A protective effect of residual beta-cell function on microvascular complications of type 1 diabetes has been suggested. Our aim was to retrospectively evaluate the association of fasting plasma C-peptide values with micro- and macrovascular complications.

RESEARCH DESIGN AND METHODS

We recruited a clinic-based cohort of 471 type 1 diabetic patients born after 1945 and cared for in the period 1994-2004. Centralized measurements and standardized procedures of ascertainment of micro- and macrovascular complications were employed. Individual cumulative averages of A1C up to 2007 were calculated.

RESULTS

Residual beta-cell secretion was detected even many years after diabetes diagnosis. In multivariate linear regression analysis, fasting plasma C-peptide values were positively associated with age at diagnosis (beta = 0.02; P < 0.0001) and triglycerides (beta = 0.20; P = 0.05) and inversely associated with diabetes duration (beta = -0.03; P < 0.0001) and HDL cholesterol (beta = -0.006; P = 0.03). The final model explained 21% of fasting C-peptide variability. With respect to fasting C-peptide values in the lowest tertile (<0.06 nmol/l), higher values were associated with lower prevalence of microvascular complications (odds ratio [OR] 0.59 [95% CI 0.37-0.94]) independently of age, sex, diabetes duration, individual cumulative A1C average during the study period, hypertension, and cardiovascular diseases. No association was evident with macrovascular complications (0.77 [0.38-1.58]).

CONCLUSIONS

Our study shows an independent protective effect of residual beta-cell function on the development of microvascular complications in type 1 diabetes, suggesting the potential beneficial effect of treatment that allows the preservation of even modest beta-cell function over time.

New potential treatments for protection of pancreatic B-cell function in Type 1 diabetes

Type 1 diabetes mellitus results from the progressive and specific autoimmune destruction of insulin-secreting pancreatic B-cells, which develops over a period of years and continues after the initial clinical presentation. The ultimate goal of therapeutic intervention is prevention or reversal of the disease by the arrest of autoimmunity and by preservation/restoration of B-cell mass and function. Recent clinical trials of antigen-specific or non-specific immune therapies have proved that modulation of islet specific autoimmunity in humans and prevention of insulin secretion loss in the short term after the onset of disease is achievable. The identification of suitable candidates for therapy, appropriate dosage and timing, specificity of intervention and the side-effect profile are crucial for the success of any approach. Considering the complexity of the disease, it is likely that a rationally designed approach of combined immune-based therapies that target suppression of B-cell specific autoreactivity and maintenance of immune tolerance, coupled with islet regeneration or replacement of the destroyed B-cell mass, will prove to be most effective in causing remission/reversal of disease in a durable fashion.

The impact of diabetes on prescription drug costs: the population-based Turin study

AIMS/HYPOTHESIS

The aim of our study was to compare prescription drug costs in diabetic and non-diabetic individuals in a large population-based Italian cohort covered by the National Health System.

METHODS

We identified diabetic residents in Turin on 31 July 2003 through multiple independent data sources (diabetes registry, hospital discharges and prescriptions data sources). All prescriptions registered in the 12 month period 1 August 2003 to 31 July 2004 were examined to compare prevalence of treatment and costs in diabetic (n = 33,797) and non-diabetic individuals (n = 863,876). A log-linear model was employed to estimate age- and sex-adjusted ratios of costs.

RESULTS

Costs per person per year were 830.90euros in diabetic patients and 182.80euros in non-diabetic individuals (age- and sex-adjusted rate ratio 2.8, 95% CI 2.7-2.9). Diabetes treatment accounted for 18.5% of the total cost. Compared with non-diabetic individuals, the excess of expenditure was particularly high in diabetic patients aged <45 years (rate ratio 9.3), in those with type 1 diabetes (rate ratio 7.7) and in insulin users (rate ratio 4.8). The cost of diet-treated patients was similar to those treated with oral drugs. Diabetes was associated with an increased prevalence of treatment for most drug categories; one-third of the diabetic cohort received ACE inhibitors, anti-thrombotic drugs and statins.

CONCLUSIONS/INTERPRETATION

This population-based study shows that diabetes has a great impact on prescription drug costs, independently of main confounders, particularly in insulin-treated patients, suggesting that a wide range of comorbidities affect their health. Costs are expected to further increase if the transferability of knowledge provided by evidence-based guidelines on diabetic patients is completed over the coming years.

A high incidence of type 1 diabetes and an alarming increase in the incidence of type 2 diabetes among young adults in Finland between 1992 and 1996

AIMS/HYPOTHESIS

The aim of this study was to examine the incidence and trends of type 1 and type 2 diabetes in the 15-39 year-old population between 1992 and 1996 in Finland.

SUBJECTS AND METHODS

Data on the nationwide incidence of diabetes were obtained from four data sources: standardised reports from diabetes nurses, the Finnish National Hospital Discharge Register, the Drug Reimbursement Register and the Drug Prescription Register. The inclusion criterion was consistency in the diagnosis of diabetes across at least two data sources. The sex- and age-specific incidence was calculated for 5-year age groups, both for type 1 and type 2 diabetes. The effects of age, sex and year of diagnosis were assessed by fitting the linear regression model to the incidence data.

RESULTS

Between 1992 and 1996 the age-adjusted incidence of type 1 diabetes among 15-39 year olds was 15.9 per 100,000/year. The incidence was highest among the 15-19 year olds and decreased with age. Conversely, the incidence of type 2 diabetes was very low among 15-19 year olds and increased with age. The total age-adjusted incidence of type 2 diabetes among 15-39 year olds was 11.8 per 100,000/year. The average annual increase in the incidence of type 2 diabetes was 7.9% (95% CI 3.7-12.2%).

CONCLUSIONS/INTERPRETATION

The age at which the Finnish population is at risk of type 1 diabetes extends into young adulthood. The rapid increase in the incidence of type 2 diabetes in the young adult population is a current public health problem.

Incidence of type 1 and type 2 diabetes in adults aged 30-49 years: the population-based registry in the province of Turin, Italy

OBJECTIVE

Incidence of type 1 diabetes is considered to be low in adults, but no study has been performed in Mediterranean countries.

RESEARCH DESIGN AND METHODS

We extended the study base of the registry of the province of Turin, Italy, to subjects aged 30-49 years in the period 1999-2001 to estimate the incidences of type 1 and type 2 diabetes. Diagnosis of type 1 diabetes was based on permanent insulin treatment or a fasting C-peptide level < or =0.20 nmol/l or islet cell (ICA) or GAD (GADA) antibody positivities.

RESULTS

We identified 1,135 case subjects with high completeness of ascertainment (99%), giving an incidence rate of 58.0 per 100,000 person-years (95% CI 54.7-61.5). The incidence of type 1 diabetes was 7.3 per 100,000 person-years (6.2-8.6), comparable with the rates in subjects aged 0-14 and 15-29 years (10.3 [9.5-11.2] and 6.8 [6.3-7.4]). Male subjects had a higher risk than female subjects for both type 1 (rate ratio [RR] 1.70 [95% CI 1.21-2.38]) and type 2 (2.10 [1.84-2.40]) diabetes. ICA and/or GADA positivities were found in 16% of the cohort. In logistic regression, variables independently associated with autoimmune diabetes were age 30-39 years (odds ratio [OR] 2.39 [95% CI 1.40-4.07]), fasting C-peptide <0.60 nmol/l (3.09 [1.74-5.5]), and BMI <26 kg/m2 (2.17 [1.22-3.85]).

CONCLUSIONS

Risk of type 1 diabetes between age 30 and 49 years is similar to that found in the same area between age 15 and 29 years. Further studies are required to allow geographical comparisons of risks of both childhood and adulthood autoimmune diabetes, the latter being probably higher than previously believed.