Due to European agreements, everyone who needs a visa for the Netherlands must be adequately covered for urgent medical costs and repatriation. If you are uninsured, then you will not receive a visa (i.e., an “MVV-/Schengen” visa). The Global Visitor insurance policy complies with the requirements for MVV-/Schengen visas.
from the brochure "Short stay visa for the Netherlands"
You are obliged to take out adequate medical travel insurance. This must cover any expenditure for repatriation on medical grounds or urgent medical care (such as urgent
treatment in a hospital).
The medical health insurance must be valid for the entire Schengen area and provide minimal coverage of € 30,000. The medical travel insurance must be valid for the entire duration of your stay. You have to submit proof of the original insurance policy either when you file the application or when the visa is issued. This depends on the possibilities in your country of origin of reimbursement of the cost incurred for insurance taken out if the visa application is denied. You can obtain information on the situation applicable in your country at the Dutch embassy or consulate.
(Immigration and Naturalisation Service December 2010 | Publication-no. 8022)