Background: Patients with type 1 diabetes (T1D) are exempt from conscript military service, but some volunteer for national service. 

Objectives: To evaluate the effect of national service (military or civil) on metabolic control and incidence of acute diabetes complications in young adults with T1D. 

Methods: Clinical and laboratory data of 145 T1D patients were retrieved from medical records. The cohort comprised 76 patients volunteering for national service and 69 non-volunteers. Outcome measures were HbA1c, body mass index-standard deviation scores (BMI-SDS), insulin dosage, and occurrence of severe hypoglycemia or diabetic ketoacidosis (DKA). 

Results: Metabolic control was similar in volunteers and non-volunteers: mean HbA1c at various time points was: 7.83 ± 1.52% vs. 8.07% ± 1.63 one year before enlistment age, 7.89 ± 1.36% vs. 7.93 ± 1.42% at enlistment age, 7.81 ± 1.28% vs. 8.00 ± 1.22% one year thereafter, 7.68 ± 0.88% vs. 7.82 ± 1.33% two years thereafter, and 7.62 ± 0.80% vs. 7.79 ± 1.19% three years thereafter. There were no significant changes in HbA1c from baseline throughout follow-up. BMI and insulin requirements were similar and remained unchanged in volunteers and controls: mean BMI-SDS one year before enlistment age was 0.23 ± 0.83 vs. 0.29 ± 0.95, at enlistment age 0.19 ± 0.87 vs. 0.25 ± 0.98, one year thereafter 0.25 ± 0.82 vs. 0.20 ± 0.96, two years thereafter 0.10 ± 0.86 vs. 0.15 ± 0.94, and three years thereafter 0.20 ± 0.87 vs. 0.16 ± 0.96. Mean insulin dose in U/kg/day one year before enlistment age was 0.90 ± 0.23 vs. 0.90 ± 0.37, at enlistment age 0.90 ± 0.28 vs. 0.93 ± 0.33, one year thereafter 0.86 ± 0.24 vs. 0.95 ± 0.33, two years thereafter 0.86 ± 0.21 vs. 0.86 ± 0.29, and three years thereafter 0.87 ± 0.23 vs. 0.86 ± 0.28. There were no episodes of severe hypoglycemia or DKA in either group. 

Conclusions: Our data indicate that during voluntary national service young adults with T1D maintain metabolic control similar to that of non-volunteers.