"I was tested for diabetes and although my results were low they weren't low enough to say I had Diabetes - during an 8 hour test I had a hypoglycemic attack, however further monitoring of my blood sugar shows normal even..."
You just contradicted yourself. You first state your had low levels but not low enough, then say you had a hypoglycemic attack. Please clarify your hypoglycemic attack. When and where did this take place? How do you know - was doctor or nurse present to test you then?
"...during the initial bloods on the 1st day my blood sugar was extremely high"
You don't mention what meds you were put on or what foods you consumed 10 hours prior to being admitted. Any could raise your glucose level.
"my father and uncle had diabetes " "I am 38 years old - slightly overweight"
You are a candidate and being "slightly overweight" makes you even more so. But earlier on you say "and have gained a lot of weight". Another contradiction. I hope you don't speak with your doctor this way.
"Can I have an intermittent diabetes problem?"
You could be borderline and/or pre-diabetes. Weight, diet, exercise play a large role in preventing and then controlling diabetes. Keep in mind certain medications can raise glucose levels. Always discuss with the pharmacist the side effects.
You may also want to schedule an appointment with a Neurologist to discuss your imbalance issues. This could be diabetes related or something going on with your cranial/nerves.
Lastly get a hemoglobin A1c (HgbA1c or HbA1c) test. Go here to read about it http://www.nlm.nih.gov/medlineplus/ency/encyclopedia_A-Ag.htm