Welcome to HCM,
You are diabetic on combination of Oral drugs and Insulin,causes for weight loss
and weakness may be many, so please visit your Physician /Endocrinologist
To enumerate possibilities development of Nephropathy causes low blood sugar
level with same diet and insulin,Anemia,any cardiac ailment,or even low grade infection or malignancy.
We need to examine and depending on that appropriate investigations like Renal function test, Urine R&M test for albumin in urine and blood Urea and Creatinine
,Complete Haemogram,EKG,X ray Chest, Abdominal Ultrasonography
may help to point out cause.
Your age peri menopausal so hormone changes and resultant blood loss may cause Anemia.
Once we know the cause treatment can be planned and you can regain good heath again.
Please get medical check up and investigations as soon as possible.
Best of Luck