Statistics from the Student Loans Company showed the amount lent to Scottish higher education students in 2015-16 was £548.3m, up 6% on 2014-15.
The average debt of students who graduated in 2015 and entered loan repayment in 2016 was £10,500 -  up from £9,410 the previous year.
Average debt remains significantly lower than in other parts of the UK.
Scottish students can borrow to pay for their living expenses but are entitled to free tuition at Scottish universities.
The vast majority of Scottish students remain in Scotland to attend university but some do study in the rest of the UK where they can borrow money to pay tuition fees of up to £9,000 a year.
The average amount owed to the company by students from England was £24,640. Welsh students owed an average of £16,120 and students from Northern Ireland £19,720.
The loans are repaid differently to normal loans - almost as if they were a graduate tax.
Graduates pay back a certain proportion of their income once it reaches a threshold until the loan is cleared. The monthly repayments are not affected by the level of debt - only the time the repayments take.
Currently Scottish graduates pay back student loans through a repayment equivalent to 9% on anything they earn over £17,495 before tax per year.
NUS Scotland said the figures did not yet include a full cohort of students who entered Scottish higher education under 2013 reforms to student support, which brought in higher loans.
The figures do not include any other debt graduates may have - for example credit card debt.
The union said debt levels would be expected to increase in coming years once the figures fully reflect the impact of these changes.
President Vonnie Sandlan said: "NUS Scotland worked incredibly hard to see increased student support and fully supported previous reforms that saw the amount of support students could access markedly increase - but it can't be escaped that this came through higher loans rather than grants.
"While increases would have been preferable in grants, and no increases at all would have been unacceptable, it's clear we need to look again at the support we provide for students, particularly our poorest and most in-need."
She added: "While previous support increases were welcome, we shouldn't be timid in going further and reforming the support system for all students in a bold and ambitious way.
"We were pleased this week to hear the Scottish government reiterate their commitment to a full review of the current student support system.
"That review could build on the work of the widening access commission and ensure that we have the support in place to not just help people into education, but to stay there and reach their full potential."
Shirley-Anne Somerville, the Scottish government's minister for further and higher education, said: "We will always take the opportunity to improve student support where we can, which is why in 2016-17 eligibility for the maximum bursary of £1,875 will expand for students who live at home in a household with an income of up to £19,000."
NUS Scotland has called for "bold and ambitious" reform of student support, as figures showed an increase in debt.