Diabetes insipidus?

When in a water deprivation test S-ADH (antidiuretic hormone) decreases between eight a'clock and eleven, does it mean diabetes insipidus? I have periods of polydipsia and dehydration. During such periods my serum osmolality is near the upper reference limit and Na+ slightly over the upper limit. Can partial diabetes insipidus be periodic.

[WaveRider]

Even though it uses diabetes in its name Diabetes Insipidus is more kidney related than irregular glucose/insulin levels [diabetes]. You should try posting on the kidney disease forum.