Inclusion Criteria:  According to the diagnostic criteria of World Health Organization (WHO) in 1999, type 2 diabetes mellitus was diagnosed clinically. The duration of T2DM was no more than 8 years (including 8 years). According to the ROME III diagnostic criteria of functional constipation or guideline for diagnosis and treatment of chronic constipation in China (2013 edition), chronic constipation was diagnosed clinically. The duration of constipation was more than 6 months (including 6 months). The age ranged from 18 to 70 years (including 18 and 70 years) with no restriction of sex. Fasting blood glucose was no more than 8mmol/L and glycosylated hemoglobin ranged from 7.0% to 10.0% (including 7.0% and 10.0%). Sign written consent form voluntarily.  Exclusion Criteria:  Other types of diabetes mellitus. History of diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome. Constipation induced by drugs[i.e. antidepressants, calcium antagonists, diuretics, sympathetic agents, antacids with aluminum or calcium, calcium agents, iron agents, antidiarrhetics]. Organic constipation [i.e. intestinal diseases，endocrine and metabolic diseases (except diabetes), nervous system and muscle disease]. Gastrointestinal diseases [i.e. colitis, mesenteric lymphadenitis, with a history of intestinal surgery]. Using drugs that may affect clinical outcome evaluation in the past 2 weeks, such as antibiotics (penicillin, amoxicillin, erythromycin, azithromycin and cephalosporin, etc.), microecological preparations, laxative drugs (magnesium sulfate and lactulose, etc.); anthraquinones (rhubarb, aloe and senna, etc.); Gastrointestinal motility drugs (metoclopramide, domperidone, cisapride, etc). History of myocardial infarction or stroke within 6 months, or existing severe cardiovascular disease and risk. Abnormal liver function [i.e. serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) is 1.5 times higher than the upper limit of normal value]. Abnormal renal function [Creatinine exceeds the upper limit of normal value]. Severe hypertension that defined as systolic blood pressure ≥160 mmHg, diastolic blood pressure ≥90 mmHg with drug therapy, or hypotension (resting seat blood pressure < 90/50 mmHg). History of acute and chronic gastroenteritis or gastrointestinal surgery Psychosis, alcohol dependence or history of drug abuse. Lactating women, pregnant women and patients who have pregnancy plan during the trial or within 3 months after the trial. Participation in other studies three months before the trial. Allergic constitution or allergic to a variety of drugs. Those researchers think inappropriate to the research.