3.9.0.0 Micronu­tri­ents and Sup­ple­ments

There con­tin­ues to be no clear ev­i­dence of benefit from herbal or non­herbal (i.e., vi­ta­min or min­er­al) sup­ple­men­ta­tion for peo­ple with di­a­betes with­out un­der­ly­ing deficien­cies (35). Met­formin is as­so­ci­at­ed with vi­ta­min B12 deficien­cy, with a re­cent re­port from the Di­a­betes Pre­ven­tion Pro­gram Out­comes Study (DPPOS) sug­gest­ing that pe­ri­od­ic test­ing of vi­ta­min B12 lev­els should be con­sid­ered in pa­tients tak­ing met­formin, par­tic­u­lar­ly in those with ane­mia or pe­riph­er­al neu­ropa­thy (123). Rou­tine sup­ple­men­ta­tion with an­tiox­i­dants, such as vi­ta­mins E and C and carotene, is not ad­vised due to lack of ev­i­dence of efficacy and con­cern re­lat­ed to long-‍term safe­ty. In ad­di­tion, there is insufficient ev­i­dence to sup­port the rou­tine use of herbals and mi­cronu­tri­ents, such as cin­na­mon (124), cur­cum­in, vi­ta­min D (125), or chromi­um, to im­prove glycemia in peo­ple with di­a­betes (35,126). How­ev­er, for spe­cial pop­u­la­tions, in­clud­ing preg­nant or lac­tat­ing women, older adults, veg­e­tar­i­ans, and peo­ple fol­lowing very low-‍calo­rie or low-‍car­bo­hy­drate diets, a multivi­ta­min may be nec­es­sary.