Over the three decades studied, diabetic children and adolescents showed improved metabolic control, and the use of rapid- and long-acting insulin analogs and intensive therapy with stricter glycemic monitoring has become widespread. In parallel, an increase in the prevalence of overweight and obesity in children and adolescents with DM1 of over 29% was observed from 1986 to 2007, with stabilization from 2007 to 2018, although with very high figures. These rates of overweight and obesity are similar to those reported in diabetic children in other Mediterranean areas (22).
In the sample studied, although the age at diagnosis of DM1 was significantly lower in the overweight and obese diabetic patients, there was no positive correlation between BMI-Z and age at diagnosis as observed by other authors (23), and the duration of diabetes showed no correlation with excess weight, as reported in other studies (24). No significant differences were observed in BMI-Z at diagnosis in the children with DM1 who had onset before 5 years of age, as postulated by the accelerator hypothesis, and being younger than 5 years of age at diagnosis was not associated with increased risk of overweight or obesity (9). The patients with onset from the age of 10 years had higher BMI-Z at diagnosis, but being > 10 years of age at diabetes onset was not associated with an increased risk of overweight or obesity.
Intensive therapy and improved metabolic control have been associated with excessive weight gain in diabetic children and adolescents (11, 25) which could partially diminish the beneficial effects of improved diabetes control on microvascular and macrovascular complications (26), although other studies have not been able to confirm this relationship (22). In our study, metabolic control improved throughout the period analyzed (Fig. 2), and the use of intensive therapy and insulin analogs was associated with a higher risk of overweight and obesity. Thus, the number of patients on intensive therapy and using insulin analogs increased significantly from 1986 to 2007 as did the rate of overweight and obesity; however, although from 2007 to 2018 the proportion of children and adolescents receiving higher doses of insulin and using insulin analogs continued to increase, the prevalence of overweight and obesity observed did not change (Figs. 3 and 4), in contrast to other studies (27).
The various environmental and biological factors that contribute to overweight and obesity in the general population, other than the insulin regimen, could mask the weight gain associated with intensive therapy and the use of insulin analogs (8, 28) and partly explain the evolution of the prevalence of overweight and obesity in diabetic children and adolescents during the period studied. The global rise in childhood overweight and obesity observed in the last forty years has shown a tendency to stabilize in recent studies (3). The pediatric population in our healthcare area, which was the source of the sample studied, has shown a similar evolution (2) with very high figures for overweight and obesity. Nonetheless, as other authors have reported (10), the incidence of DM1 does not show a linear relationship with excess body mass, and during the period studied, the incidence of DM1 in children and adolescents continued to increase steadily in Europe (4), North America (29, 30), and Spain (5). As other authors have observed in the adult population with DM1 (31), our findings reveal an increase in the prevalence of overweight and obesity in diabetic children and adolescents, with stabilization in the last ten years, similar to that seen in the population from which the sample was drawn (2, 32), as shown in Fig. 5. The relationship between the distribution of overweight and obesity in diabetic children and adolescents and the childhood obesity epidemic has also been suggested by other authors (28). Factors such as genetic predisposition (33), an obesogenic environment (24), and the microbiome (8), which promote obesity and increased insulin resistance in the general population, would also affect diabetic children and adolescents.
Although the rate of obesity and overweight in diabetic children and adolescents has stabilized in our healthcare area, the figures are still very high, contributing to an increased risk of hypertension, dyslipidemia, and early cardiovascular disease in this susceptible population (30). The effect of overweight and obesity on the metabolic syndrome in diabetic patients has been studied in children (13, 30) and especially in adults (11, 31), in whom obesity has been associated with an increased risk of hospitalization (34). These findings underscore the importance of early diagnosis and treatment of excess weight and its metabolic consequences in this at-risk group. Diabetes management encouraging healthy eating and exercise is key to preventing obesity, overweight, and cardiovascular disease.
Limitations
This study has several limitations, including its retrospective design and that it was undertaken at a single center serving a single health department, and therefore the number of patients was small. Other limitations were the lack of data on the pubertal status of the patients and the lack of waist circumference to estimate the metabolic syndrome with the criteria currently used. As strengths, this study covers the evolution of three groups of children with DM1 (n = 136) over the last 30 years in a health area for which we have data on overweight and obesity in the source population. The criteria used to define these groups were homogeneous and based on international standards. The strength of these observations lies in the comparison of the same time period and ages.