Food in real life

Protein shakes and supplements

A plain protein powder and a mass gainer are different products in similar packaging. What to read on the label, and why the training matters more.

Written by Updated 11 January 2025 6 min read
The 60-second answer

Protein shakes and gym supplements are not off limits with type 1, and most of the confusion around them comes from treating the category as one thing. What matters is what is actually in the tub, and the label answers it in about ten seconds.

  • A plain protein powder carries very little carbohydrate. A mass gainer or recovery blend can carry a great deal.
  • Protein on its own tends to nudge glucose up slowly and modestly, not the way carbohydrate does.
  • ”Sugar free” is not the same as carb free, and the carbohydrate line is the one to read.
  • These are taken around training, so the exercise effect usually matters more than the shake does.
  • What you drink is yours to decide; how much insulin any of it needs is worked out with your diabetes team.
What is in it

Three very different products with one name

A plain whey or plant protein powder is mostly protein, with a small amount of carbohydrate per scoop. Protein does have a glucose effect, but it is slower and gentler than carbohydrate: it tends to produce a small, late nudge upward rather than a rise you would notice in the first hour.

A mass gainer or a recovery blend is a different product wearing similar packaging. These are designed to deliver a large amount of carbohydrate alongside the protein, sometimes as much as a full meal, and that is the whole point of them rather than a hidden ingredient. They behave like the carbohydrate they contain, which is to say quickly.

Bars and ready-to-drink shakes sit somewhere in between and are the most misread of the three, because the front of the packet is doing marketing while the back is doing the arithmetic. “High protein”, “sugar free” and “no added sugar” all describe something other than total carbohydrate, and a bar can carry a fair amount from oats, syrups or sugar alcohols while being technically accurate on the front.

Around training

The exercise usually matters more than the shake

Almost all of this gets taken around exercise, and that context tends to dominate. Steady aerobic work such as a long run or a swim usually pulls glucose down, while short intense effort such as heavy lifting, sprints or a competitive session often pushes it up for a while, and a session that mixes the two can do both in an hour. So the same shake after two different sessions is not the same situation.

The timing that catches people out is afterwards. A low can arrive during the session or straight after it, and it can also arrive many hours later, including overnight, because muscles carry on restocking long after you have left the gym. A recovery shake lands right in that window, which is part of why it exists, and it is also why the evening after a hard session deserves more attention than the hour after it.

What to do about all this belongs with your team, and it is a genuinely useful conversation to have because they will have had it before. Going in with what you actually take, when you take it, and what the label says is far more productive than asking about supplements in the abstract.

The rest of the shelf

Creatine, pre-workout and everything else

Creatine is the other one people ask about. It has no direct effect on glucose, so it is not an insulin question, though it does draw water into muscle and can move the number on the scales in a way that has nothing to do with fat or fluid balance elsewhere. Worth knowing so a weight change does not get misread.

Pre-workout is mostly caffeine, often a lot of it, and caffeine is worth taking seriously for a different reason. It can nudge glucose up on its own, and it produces jitteriness, a racing heart and sweating, which are the same signals a hypo produces. Something that makes a low harder to recognise, taken immediately before exercise, is a combination worth being deliberate about rather than casual with.

Beyond that, supplements are not regulated the way medicines are, so what is on the label is not verified the way a prescription is. Anything new, and particularly anything herbal or anything claiming to affect blood sugar directly, is worth mentioning to your team or pharmacist before you start it, especially if you take other medication.

What varies

What decides how a shake lands

The carbohydrate line does most of the work here, and it is the one number worth finding before anything else. Session type matters nearly as much, since a shake after a steady hour is a different problem from the same shake after heavy lifting. And a double scoop is double the arithmetic, which is easy to forget when the label quotes one.

plain protein or a gainerwhat the carbohydrate line saysbefore or after trainingwhat kind of session it washow hard it wascaffeine in ithow much of it you have
Real-life examples

Same shelf, different problems

Examples, not instructions or doses.

The plain scoop

A basic protein powder in water, carrying very little carbohydrate. A small late nudge upward at most, and nothing like a meal.

The gainer

A recovery blend built to deliver a lot of carbohydrate alongside the protein. That is the product working as intended, not a hidden ingredient.

The bar that said sugar free

A front of packet claim that describes something other than total carbohydrate. The number that matters was on the back.

What to notice

Worth paying attention to

Reading the carbohydrate line rather than the front of the packet, since "sugar free" describes something else
That plain protein powder and a mass gainer are completely different products with similar packaging
That steady exercise tends to lower glucose while short intense effort often raises it, so the session changes the picture
That a low can come during or straight after a session and also many hours later, including overnight
That caffeine in pre-workout can nudge glucose up and makes a hypo harder to recognise
Telling your team or pharmacist about anything new, especially herbal products or anything claiming to affect blood sugar
What to ask your team

Questions that make an appointment useful

"I use a protein shake after training, is there anything I should be doing differently around it?"
"How should I handle a recovery drink that carries a lot of carbohydrate?"
"What should I be watching for in the evening after a hard session?"
"Is there anything on this list I should not be taking with type 1?"
"I take a pre-workout with caffeine in it, does that change how I should be checking?"
Sources