RecruitingDietary supplementEffect of 4 Weeks of Oral Probiotic Desulfovibrio Piger Supplementation on Immunological and Metabolic Parameters in Individuals With Longstanding Type 1 DiabetesThe goal is to establish the effect of oral probiotic Desulfovibrio piger (D. piger) supplementation on immunological and metabolic parameters in individuals with longstanding type 1 diabetes with residual beta cell function. The investigators will perform a double-blind, randomized, placebo-controlled trial in 2x10 participants to measure effects of D. piger on parameters of systemic and intestinal inflammation and residual beta cell function.