It depends whether it's your skin that is itchy in which case something as simple as a moisturizer may be enough, perhaps one of the medicated over the counter itch relief creams all the way up to a topical steroid cream in extreme cases.

If it's "nerve itch" due to nerve damage from high blood sugar which would require specific diagnosis and prescription to alleviate the "itch" but not fix the problem - but only a doctor and may require a specialist to advise.

That happens to me every time my sugar is high. I’m trying to limit carbs during the day to cut down on the tiredness.