Hi Mr. Mitra, 
As you have not mentioned the duration of your Diabetes specifically,let by your  narration my interpretation is you have recently detected Diabetes iabetes approximately one and half month back. 
You have started on  Glycomet Sr 1 gm before dinner, along with you are doing yoga, gym, walk regularly diet control. 
With all this efforts your blood sugar levels are fairly controlled. 
I would like to advise_
1. Strictly follow Diabetic diet regularly. 
2. Continue yoga, gym, walk regularly. 
3. Continue Tab Glycomet Sr 1gm after dinner. 
In fact you can increase the dose upto 1.5 gm  and over  another 15 days to 2 gm total per day in divided doses preferred to take after meals. (effective dose is approximately 1.75 gm per day) 
As this medicine rarely  decreases blood sugar levels below normal level (rarely causes 
hypoglycemia) 
This medicine act on basic pathology of diabetes called 
insulin resistance. 
As Diabetes is life long disease, as duration of diabetes increases there may need of additional medicines. 
4. You have not mentioned your height and weight so that you should target 
weight loss according to your height. 
5. Certain 
blood test are important like 
lipid profile, 
serum creatinine, HbA1C which denote blood sugar level over period of approximately 120days.
Urinary protein creatinine ratio, Fundoscopy to rule out 
diabetic retinopathy. 
6. You should also start medicine for lowering lipids despite your lipid level, if it is in normal range start in basic dose and if in higher doses according to   lipid level. 
7. Also regular BP checking