Fiona Riches went missing from her home on Monday afternoon. Her familyand police are concerned her volatile type 1 diabetes, requiring insulin twice daily, could mean her health has deteriorated rapidly.

Sergeant Reece Strachan said while emergency services were continuing their search for the missing 46-year-old, hope for her safe return was fading.

"Given Ms Riches medical condition and the real possibility she may have fallen into a diabetic coma I am fearing the worst," Sergeant Strachan said.

The search from Police, SES volunteers and the Snowy Hydro South Care helicopter has stretched from Curtin in the north to Farrer in the South.

The search has also spanned from Mt Taylor to Red Hill where police and SES volunteers are currently searching.

Thermal imaging technology was used on Tuesday night in an attempt to locate Ms Riches.

"At this stage the search is continuing today … later today we'll be using the helicopter again today to do a daylight sweep of the search areas," Sergeant Riches said.

Police are still hoping locals in the area may help provide clues to her disappearance.

Police said she may now be disoriented or confused.

She is Caucasian, 170cms tall, with a medium build, fair complexion and shoulder length light-brown hair.

She walks with a distinctive limp.

The missing woman was last seen wearing a long-sleeve black and red checked shirt, blue jeans and white sneakers.

Anyone with information should call ACT Policing on 131444 immediately.