Epidemiological studies suggest a link between vitamin D deficiency in early life and the later onset of type 1 diabetes. The aim of this matched case-control study was to find the association between vitamin D and T1DM then to study the difference in the level of vitamin D in T1DM and healthy subjects, and to determine the associated environmental risk factors in young Qatari population.

The study was carried out among T1DM children and healthy subjects below 16 years at the pediatric endocrinology outpatient clinics of the Hamad General Hospital and the Primary Health care Clinics (PHCs). The survey was conducted over a period from 6 August to 25 December 2007. The subjects were Qatari nationals male and female aged below 16 years. The study is based on matching by age, gender and ethnicity of 170 cases with those of 170 controls. Face-to-face interviews were based on a questionnaire that included variables such as socio-demographic information, assessment of non-dietary covariates, assessment of dietary intake, vitamin D intake, type of feeding, clinical manifestations and laboratory investigations. Their health status was assessed by medical conditions, family history, BMI, past or present clinical manifestations, 25 (OH)D, Calcium, alkaline phosphatase, phosphorus, HbA1C, PTH, Mg and creatinine analysis.

The study revealed that vitamin D deficiency was considerably higher in T1DM children (90.6%) compared to non-diabetic children (85.3%). There was a significant difference found in the mean value of vitamin D between T1DM and non-diabetic children (P = 0.009). There were statistically significant differences between type 1 diabetic and healthy subjects with respect to the occupation of parents (P < 0.001) and consanguinity rate (P < 0.047). Family history of vitamin D deficiency was considerably higher among T1DM children (35.3%) with a significant difference between diabetic and non-diabetic children (22.9) (P < 0.012).

Vitamin D supplement with breast milk was very poor in diabetic children (37.4%) compared to non-diabetic children (47.7%). Majority of the studied subjects were breast-fed children (95.1% of diabetic children and 97.2% of healthy children). Multivariate logistic regression analysis revealed that fathers and mothers occupation, family history of DM, physical activity, low duration of time under sun light, breast feeding less than 6 months and low vitamin D level were considered as the main factors associated with the T1DM. In conclusion, the present study revealed that vitamin D deficiency was higher in T1DM children compared to non-diabetic. Moreover, vitamin D deficiency was common in Qatari young population.

Vitamin D intake was very poor in children and it shows that supplementing infants with vitamin D might be a safe and effective strategy for reducing the risk of T1DM.

Keywords: Diabetes Mellitus Type 1 - Vitamin D Deficiency