PURPOSE: A composition containing Codonopsis lanceolata extract or fraction thereof is provided to prevent and treat diabetes and diabetes related complications without side effects and toxicity. CONSTITUTION: A composition for preventing or treating diabetes or diabetes complication contains Codonopsis lanceolata extract isolated using 60-80%(v/v) acetone; or fraction which is obtained by fractioning the extract with alkane of C5-C7, methylene chlrodie, or ethyl acetate. The Codonopsis lanceolata is used in raw form or steamed form. Diabetes complication is diabetic retinopathy, diabetic cataract, diabetic nephropathy, diabetic neuropathy, and diabetic vascular complication.더덕(Codonopsislanceolata) 추출물 또는 상기 추출물의 분획물을 유효성분으로 함유하는 당뇨 및/또는 당뇨합병증의 예방 및/또는 치료용 조성물이 제공된다.