The strike, due to begin tomorrow at 8am, is the third this year in the action by Unison mem-bers at care homes for the elderly across the city.
They are fighting against changes to shift patterns and job roles, which may result in pay cuts of up to £1495 a year for some staff.
But the council says most employees have already agreed to the changes which came into force at the end of last month. They say workers were consulted over the new terms, which allow for more weekends off.
Unison has raised concerns over the move to 12-and-a-half hour shifts and claim the staff-to-resident ratio on the new night shift is inadequate.
There are around 600 residents in the homes affected, which have about 500 staff.
In a letter to David Williams, the executive director of social work services at Glasgow City Council, Unison branch secretary Brian Smith and health and safety officer Scott Donohoe raised these issues.
They said: "We have major concern with the potential impact of the changes to working patterns and extended shift work on our members' health and wellbeing. Shift work has been linked to higher rates of Type 2 diabetes, heart attacks and cancer."
Mr Smith added: "Unison members have voted unanimously to up the action and move to three days of strike action as social work services' senior management is still refusing to resolve the dispute.
"The council has tried to bully workers into agreeing to the wage cuts and changes on an individual basis and they have been unwilling to reach an agreement with the trade union.
"Unison members do not take this strike action lightly but have been left with no alternative. The purpose of the action is to force the council to reach a negotiated settlement."
A spokesman for the Scottish Care Inspect-orate, which has been liaising with the council over the potential risks to the homes' residents, said: "We are aware of the potential for industrial action at a number of council-run residential care homes and are in close contact with Glasgow City Council.
"In any situation like this we expect contin-gency measures to be in place to ensure the vital services provided to residents are not affected and that their rights are respected and their needs met.
"We will be working closely with the council to ensure that this is the case."
SNP Group spokes-woman for health and social care Susan Aitken said the council was using "macho-management tactics" by refusing to negotiate with Unison during the row.
She added: "Social work management need to take on board what staff are asking for. We back the workers' choice to take action but it should have never got this far."
A spokesman from Glasgow City Council said: "Talks with Unison have been ongoing and it is possible the strike action can be averted.
"However, contingency plans have been drawn up and we are confident these will allow the homes to be run as close to normal as possible.
"Twelve-hour shifts are successfully deployed by many other organisations, including the NHS, without raising any health concerns."