Evaluation of The Chinese Herbal Medicine (T50) as Add-on Treatment to Metformin Monotherapy in Participants with Type 2 Diabetes Mellitus: A 12-week randomised, double-blind, placebo-controlled pilot clinical trial

INTERVENTION: • Treatment Arm: metformin tablet (equal to 1000 mg/day) plus Tang Minling Pills (T50) 7.5g twice a day by oral administration. The duration of intervention is for 12 weeks. • Control Arm: metformin tablet (equal to 1000 mg/day) plus placebo pills 7.5g twice a day by oral administration. The duration of intervention is for 12 weeks for 12 weeks. • Strategies used to monitor adherence to the intervention of treatment arm and control arm: Participants will receive a 4‐ weeks’ supply of Tang Minling or placebo Pills and prescribe 4 weeks' dosage of metformin tablets. The follow‐up assessments (physical examination and laboratory tests) will be performed every four weeks during the treatment phase. All participants will be asked to return all empty pockets of investigational product for reconciliation at each follow‐up assessment. • The composition of Tang Minling Pill: Investigational Product (IP) of T50 pill (Tang‐Min‐Ling‐Wan, Tang Minling Pills) is a formulation derived from a classic formula described in the Treatise on Exogenous Febrile Diseases over 1000 years ago. The ingredients in manufactured T50 include herbal extracts of Dahuang (Rhei Radix et Rhizoma), Huanglian (Coptidis Rhizoma), Baishao (Paeoniae Radix Alba), Chaihu (Bupleuri Radix), Huangcen (Scutellariae Radix), Zhishi (Aurantii Fructus Immaturus), Qingbanxia (Pinelliae Rhizoma Praeparatum Cum Alumine), Shanzha (Crataegi Fructus), Wumei (Mume Fructus), and Tianhuafen (Trichosanthis Radix). The proportion for each component in the T50 formulation is based on dosage ranges in the Chinese Pharmacopeia 2015. CONDITION: Alternative and Complementary Medicine ‐ Other alternative and complementary medicine Metabolic and Endocrine ‐ Diabetes Type 2 Diabetes Mellitus; ; Type 2 Diabetes Mellitus PRIMARY OUTCOME: Change in HbA1c at 12 weeks relative to baseline for T50 compared with placebo will be assessed by measuring fasting plasma HbA1c. [The fasting plasma HbA1c will be assessed at baseline (before treatment), every four weeks during the treatment period and at the end of 12 weeks treatment. ] SECONDARY OUTCOME: Changes in body weight relative to baseline and comparing to placebo control[Body weight will be measured using a scale at week 0 (before treatment), every four weeks during the treatment period and at the end of 12 weeks treatment.] Changes in insulin sensitivity relative to baseline and comparing to placebo control ; ; [Insulin sensitivity will be calculated using fasting plasma glucose and insulin levels for HOMA‐IR and HOMA‐ß at week 0 (before treatment), every four weeks during the treatment period and at the end of 12 weeks treatment. ; ; ; ; ] Changes in metabolic parameter ( a composite including fasting plasma glucose, insulin levels and plasma lipid profile) relative to baseline and comparing to placebo control INCLUSION CRITERIA: 1. Male or Female, aged is equal to or greater than 18 and less than 80 years 2. A confirmed diagnosis of Type 2 Diabetes Mellitus (T2DM) based on American Diabetes Association (ADA) guidelines and taking a stable dose of metformin (equal to or greater than 1000 mg/day) as monotherapy for at least 1 month prior to screening. 3. A glycosylated haemoglobin (HbA1c) level between 7% and 9% at the screening visit. 5. Participants who are able to understand and comply with all study related procedures. 6. Participants who give written informed consent having read the Information Sheet for volunteers. 7. Participant with ability to read and write English. ; [The fasting blood sample for measuring glucose, insulin and lipid profiles will be collected at week 0 (before treatment), every four weeks during the treatment period and at the end of 12 weeks treatment.] Changes in quality of life assessed using the ‘Traditional Chinese Medicine Symptom Scoring Standard’ and the Assessment of QoL questionnaire (AQOL).[The quality of life will be assessed using the ‘Traditional Chinese Medicine Symptom Scoring Standard’ and the Assessment of QoL questionnaire (AQOL) at week 0 (before treatment), every four weeks during the treatment period and at the end of 12 weeks treatment.] Tolerability of T50 in combination with metformin, e.g. stomach uncomfortable and diarrhoea, will be assessed by study‐specific questionnaire and participant self‐reported.[During the study period, the investigator or site staff will be responsible for detecting adverse effects which may be relevant to administration of T50 in combination with metformin at each follow‐up assessment.] 4. Females of childbearing potential must have a negative pregnancy test, not be breast feeding and be established on a reliable method of contraception. Females must agree to remain on their established method of contraception throughout their participation in the study.