Conservative MP for St Ives, Derek Thomas, claimed diabetes is "completely avoidable through good diet and exercise" on his Facebook page.
Dozens of constituents in Cornwall complained that his comments were inaccurate and "insulting".
He said he was "sincerely sorry" and would raise the issue with government to prevent confusion in future.
Mr Thomas' post provoked more than one hundred comments, many of which pointed out that type 1 diabetes "is genetic", and type 2 diabetes, which is often linked to obesity, is "not preventable for all".
Orson Cornick commented: "Being an ignorant human being is avoidable, not type 1 diabetes!"
Marianna Baxter whose daughter has type 2 diabetes said she was "very angry and hurt" at the "very offensive" remarks.
Mr Thomas told the BBC he was told the information by "two medical professionals" and had simply been trying to raise awareness that many people can help themselves by improving their diet.
He said: "I certainly got it wrong and I apologise for that. I certainly wasn't going out to intentionally upset a number of people that can do nothing about their ill health, so I do apologise for the way that was worded."
He said he would raise the issue with the government ahead of its national diabetes strategy launch next year to make sure no discrimination took place.
Mr Thomas removed the post on Saturday and replaced it with another offering a "sincere apology".
Many commended him like Charlotte Clews who commented: "I stand up and applaud you. So does my type one son. It really is very heart warming to see that you have corrected a mistake and educated yourself and now others."
The charity Diabetes UK declined to comment but said information on any link with diet and lifestyle was available on its website.

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19 May 2015 Last updated at 00:20 BST
The interactive 3D renderings are assembled from photos of the objects, sourced from tourists who visited them before the destruction.
So far the project has received more than 700 photos and produced 15 3D images of artefacts, mostly from the ransacked Mosul Museum.
The archaeologists who established the project hope to widen its scope to include objects lost at other sites, to violence or natural disasters such as the recent Nepal earthquakes.

Gian-Franco Kasper, a Swiss ski official, made the comparison during an IOC board meeting in Pyeongchang.
The board is debating whether to suspend the entire Russian team from the Games following a doping scandal.
"I apologise unreservedly for any offence I have caused. I am truly sorry," Franco Kasper said.
The International Ski Federation President was discussing a proposed blanket ban on Russian athletes when he made the Holocaust comment, referring to the World War II genocide that saw six million Jews killed by Adolf Hitler's Nazi Germany.
He reportedly said: "I'm just against bans or sanctioning of innocent people. Like Mr Hitler did - all Jews were to be killed, independently of what they did or did not do."
When challenged by reporters at the time, Franco Kasper responded: "Why not? Of course it's more extreme. But just the fact that the place you come from makes you guilty, I'm not OK for this, really not."
Russia did not receive a blanket ban from the IOC from the 2016 Olympics in Rio, opting to leave the decision to individual sports' governing bodies.
A report in December 2016 claimed Russian medallists from summer and winter Olympics had benefited from a state-sponsored doping programme between 2011 and 2015.
An MP has apologised for his "very offensive" and "damaging" comments on diabetes.
[NEXT_CONCEPT]
In an initiative called Project Mosul, cyber-archaeologists and volunteers are re-creating works of art destroyed by IS militants in Iraq.
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An International Olympic Committee (IOC) board member has apologised for comparing calls to ban Russia from the 2018 Winter Olympics to the Holocaust.