Brief Answer:
Possibly yes

Detailed Answer:
6.8 is quite good.

Metformin in anyone older than 80 should be used only after ensuring good kidney function.

However, I would generally avoid metformin in this situation and prefer an alternative like sitagliptin.
Typically, the glucose targets in older individuals are not as stringent as in the younger group. When I see someone like you in my practice, I typically order the following blood tests in addition to a detailed physical examination:

CBC (Complete Blood Count, also known as Hemogram; includes Hemoglobin, WBC and Platelet counts)
Electrolytes (Sodium and Potassium in particular)
HbA1c (Glycosylated Hemoglobin = your last 3 months' glucose average). Also known by other names such as GlycoHemoglobin or Glycated Hemoglobin or A1c
Liver function tests (SGOT , SGPT, Albumin, Bilirubin, Alkaline Phosphatase)
Kidney function tests (BUN, Creatinine)
TSH (checks your thyroid) 12 hour Fasting Lipid profile
Urine albumin to Creatinine Ratio (early sign of diabetes affecting the kidney)
25 hydroxy Vitamin D levels (ideal range 40 to 60 ng/ml = 100 to 150 nmol/liter)

Correct diagnosis and treatment requires the opportunity to examine the patient so you must see an endocrinologist in-person.

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