Yes, dehydration can increase glucose levels.
Dehydration decreases blood volume which concentrates glucose levels. A general starting point for baseline daily fluid needs is 2.7 L (90 fl oz) of water per day for women and 3.7 L (125 fl oz) of water per day for men.
References:
1. Roussel R, et al. Low water intake and risk for new-onset hyperglycemia. Diabetes Care. 2011 Dec;34(12):2551-4. doi: 10.2337/dc11-0652.
2. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies Press; 2005. https://doi.org/10.17226/10925.