The number of people holding a chartered title through the Chartered Insurance Institute (CII) has fallen for the first time since 2008, according to the body's annual report.
The report showed there were 23,137 people holding one of the CII's chartered titles during 2017 compared with 23,266 in the previous year.
Meanwhile the CII's level of "engaged membership" only went up by 61 - from 124,863 in 2016 to 124,924 in 2017.
A spokeswoman for the CII said: "Although some individual chartered titles have plateaued we continue to see significant growth in those obtaining chartered financial planner.
"We have also seen growth in corporate chartered and are in the process of launching a consultation paper to seek the views of members on the current criteria."
She said 11 years on from the launch of the three corporate chartered titles - chartered insurers (CI), chartered insurance brokers (CIB) and chartered financial planners (CFP) - the CII planned to evolve the corporate chartered proposition to make it more modern, relevant and inclusive to address the needs of a more diverse membership base.
"The profession continues to actively seek chartered status and, in 2018, companies including RSA Claims, Chubb and Covea have all been proud to join the growing chartered community," she added.
The CII said it is seeking to introduce a new chartered title for managing general agents, given their increased importance in the UK and international insurance sector by December 2018 dependent on Privy Council and member approval.
In terms of the CII's membership, the spokeswoman said timing played a factor in this figure because renewals take place throughout the year rather than on a specific date.
She added: "The CII continues to see positive membership growth and we are focused on improving engagement with our members through the delivery of more valued membership experiences."
Across other measures the CII showed improvement, with 2,000 more enrolments in the CII's new units at 13,842 and the number of people attending CII events, which promote the profession to new talent, standing at 30,000, up from 9,910.
In June the CII moved from his historic Aldermanbury headquarters to Lombard Street in a move which the organisation said would allow it to become "modern, relevant and diverse" and the new headquarters will be "open plan, fully up-to-date and technologically sound".
But the move has been controversial, with some employees at the CII taking to staff feedback website Glassdoor to accuse the body's chief executive of hating the old building and being determined to move the organisation out of it "even if she has to make the business bankrupt to do it" - allegations the CII has defended.
Sian Fisher, who was appointed chief executive of the CII in 2016, said in January the CII was "completely transparent" about how it uses its funds, which are set out in its annual report.