Does Ensure Raise Blood Sugar?

Standard Ensure and similar nutritional shakes raise blood sugar, sometimes substantially, because they contain significant amounts of carbohydrate, including sugars. An 8-ounce bottle of Ensure Original delivers around 32 grams of carbohydrate, with roughly 15 grams coming from sugars. For someone with diabetes or prediabetes, that is comparable to eating two slices of white bread in liquid form, and the liquid format means it gets absorbed quickly. The real question is how much it spikes blood sugar and what you can do about it, because the answer changes dramatically depending on which product you choose and how you consume it.

What Standard Ensure Does to Your Blood Sugar

When you drink a standard nutritional supplement like Ensure Original, your body processes the carbohydrates rapidly. The main carbohydrate sources in most standard formulas are corn maltodextrin and sugar (sucrose), both of which break down into glucose quickly. Corn maltodextrin in particular has a glycemic index that rivals pure glucose. The result is a fast, noticeable rise in blood sugar within 15 to 30 minutes of drinking it.

Clinical trials consistently show that standard oral nutritional supplements produce a meaningful postprandial glucose spike. In one crossover trial comparing a standard supplement to a diabetes-specific formula in people with prediabetes, the standard drink produced a postprandial glucose area-under-the-curve roughly two and a half times larger than the diabetes-specific version.¹ That is not a subtle difference. If you have normal insulin function, your body can handle this spike and bring glucose back down. But if your insulin response is impaired, that spike lingers longer and climbs higher.

The protein and fat in Ensure do slow absorption somewhat compared to drinking the same amount of sugar dissolved in water. But they do not eliminate the spike. You are still consuming a concentrated carbohydrate load in liquid form, and your gut processes liquids faster than solid food.

Why Liquid Meals Spike Blood Sugar Faster Than Solid Food

One underappreciated reason Ensure hits blood sugar hard is that it is a liquid. Your stomach empties liquids more rapidly than solid food, which means the carbohydrates reach your small intestine and enter your bloodstream sooner. Research on meal dilution found that increasing the volume of a liquid meal significantly increased the glycemic response for glucose, sucrose, and fructose alike, with higher blood sugar concentrations showing up as early as 15 minutes after consumption.² The mechanism likely involves faster gastric emptying when the stomach contents are more fluid.

This matters practically. If you ate a solid meal with the same macronutrient profile as a bottle of Ensure, the fiber, chewing, and slower stomach emptying would produce a lower, more gradual blood sugar curve. With a shake, you bypass most of those natural braking mechanisms. That does not make Ensure inherently bad, but it means you should treat it more like a fast-acting carbohydrate source than like a balanced meal, especially when planning insulin doses or timing.

Diabetes-Specific Formulas Are a Different Story

Abbott (the maker of Ensure) and other companies sell diabetes-specific versions of nutritional shakes, such as Glucerna. These formulas are designed to produce a smaller blood sugar spike, and the evidence shows they actually deliver on that promise. The carbohydrate blend in diabetes-specific formulas typically swaps out fast-acting sugars for slower-digesting carbohydrates like isomaltulose and resistant maltodextrin, and adds more fiber, protein, and monounsaturated fat.

In a 12-week study of people with diabetes, postprandial glucose responses were significantly lower after the diabetes-specific formula compared to the standard formula at every visit. Over the 12 weeks, the diabetes-specific group also showed a trend toward decreasing glucose spikes over time, while the standard group showed no such improvement.³ A separate crossover trial in people with prediabetes found similarly dramatic results: the diabetes-specific formula cut the postprandial glucose response to less than half of what the standard formula produced, and also lowered insulin demand significantly.¹

If you have diabetes or prediabetes and need a nutritional supplement, a diabetes-specific formula is the obvious choice. They cost roughly the same and taste similar. The standard version is not formulated with blood sugar in mind, and the difference in glycemic impact is large enough that it matters clinically, not just statistically.

How Fiber and Protein Blunt the Spike

Two ingredients explain most of the difference between formulas that spike blood sugar and those that do not: soluble fiber and protein.

Soluble dietary fiber, particularly viscous types like gums, psyllium, and beta-glucan, forms a gel-like layer in your gut that physically slows the absorption of glucose. A review of the evidence found that soluble fiber consistently reduced glycemic responses when added to carbohydrate-rich foods and beverages.⁴ A study in healthy adults confirmed that adding water-soluble fiber to a glucose drink significantly reduced both the sharp initial rise and the sustained elevation of blood sugar afterward.⁵ Standard Ensure contains minimal fiber. Diabetes-specific formulas typically contain several grams per serving, which partly accounts for their better glycemic profile.

Protein also helps. Whey protein in particular slows gastric emptying and stimulates the release of GLP-1, a gut hormone that enhances insulin secretion and helps regulate blood sugar. In a crossover trial comparing a whey-protein-based nutritional drink to a standard chicken-and-rice meal, people with type 2 diabetes had a 63% lower glycemic response after the whey protein drink, along with 141% higher GLP-1 secretion.⁶ The branched-chain amino acids and bioactive peptides in dairy-based protein appear to be especially effective at stimulating this hormonal response. If you are choosing between nutritional supplements, ones with a higher protein-to-carbohydrate ratio will generally produce a more moderate blood sugar curve.

The “Less Sugar” Label Can Create a False Sense of Security

Ensure now sells several reduced-sugar and sugar-free variants. These are marketed to health-conscious consumers and people with diabetes, and the labels prominently feature phrases like “less sugar” or “sugar-free.” But these labels deserve some skepticism.

Products with reduced sugar often replace sucrose with non-nutritive (artificial or natural zero-calorie) sweeteners. A systematic review of studies on non-nutritive sweeteners and glucose homeostasis found that while these sweeteners triggered some physiological responses, they failed to significantly lower blood glucose levels in almost all studies examined.⁷ In other words, swapping sugar for sucralose or stevia does not mean blood sugar stays flat. The product may still contain other carbohydrate sources like maltodextrin that raise glucose nearly as much as sugar does.

Research on consumer perception has shown that “less sugar” claims create a health-halo effect, making people rate products as healthier than they actually are. In one study, a “30% less sugar” label significantly increased health assessments of otherwise unhealthy products, and only a clear front-of-pack nutritional rating was able to correct that misperception.⁸ If you are managing blood sugar, read the full nutrition label. Look at total carbohydrates, not just sugars, because maltodextrin and other glucose-producing carbohydrates count toward the glycemic load even though they are technically not “sugar.”

How Drinking Speed and Timing Affect the Response

How quickly you drink a shake matters more than most people realize. Downing a bottle of Ensure in two minutes delivers the full carbohydrate load to your stomach at once, prompting rapid emptying and a steep glucose spike. Sipping the same bottle over 20 to 30 minutes spreads the carbohydrate delivery and gives your insulin response more time to keep up.

Research on enteral feeding methods supports this idea. A study comparing bolus feeding (delivering a full serving all at once) to continuous slow feeding in hospital patients found that blood sugar levels were significantly lower in the continuous-feeding group by the second day, while the bolus group saw blood sugar rise over the same period.⁹ You are not using a feeding tube at home, obviously, but the principle translates: slower delivery means lower peaks.

Timing relative to meals also matters. Drinking Ensure on an empty stomach in the morning, when cortisol levels are naturally higher and insulin sensitivity can be lower, tends to produce a stronger spike than having it alongside or after a mixed meal that includes solid food, fat, and fiber. If you are using Ensure as a supplement rather than a meal replacement, pairing it with a handful of nuts or a serving of vegetables adds fiber and fat that slow absorption.

Ensure at Bedtime and Overnight Blood Sugar

Some people with diabetes drink Ensure or similar shakes before bed to prevent overnight low blood sugar, especially those on insulin. This is a legitimate use, but the type of shake matters. A standard Ensure before bed will cause an initial glucose spike, which may then be followed by a drop as insulin (either endogenous or injected) brings glucose down, potentially overshooting into hypoglycemia in the middle of the night.

A crossover trial in adults with type 1 diabetes found that having a bedtime snack of any kind dramatically reduced nocturnal hypoglycemia compared to having no snack at all. Roughly 71% of hypoglycemic episodes occurred when no snack was consumed. Standard snacks and protein-rich snacks both eliminated nocturnal hypoglycemia entirely when pre-bedtime glucose was already in a reasonable range.¹⁰ The takeaway for Ensure users: a protein-rich formula at bedtime is more effective at preventing overnight lows than a sugar-heavy standard version, because the protein sustains glucose release over a longer period without producing the sharp spike-and-crash pattern.

Meal Replacements and Longer-Term Blood Sugar Control

Beyond the acute spike-per-serving question, there is a separate issue: can structured meal replacement with products like Ensure actually improve blood sugar management over time? For people with type 2 diabetes who use meal replacements as part of a weight-loss or calorie-control strategy, the evidence is encouraging.

A 52-week study of people with poorly controlled type 2 diabetes found that those who replaced one to two meals daily with a structured meal replacement plan saw a clinically meaningful drop in HbA1c of about 0.8 percentage points, while a control group showed no significant change.¹¹ A separate 6-month program using full meal replacement in adults with obesity and type 2 diabetes found significant improvements in HbA1c across both groups studied.¹² A third study in type 2 diabetes patients requiring high insulin doses found that partial meal replacement reduced HbA1c from 8.8% to 8.1% over 12 weeks, with continuing users seeing further improvement.¹³

The mechanism here is not that meal replacements are magical. It is that they enforce portion control and provide a predictable carbohydrate load. When someone with diabetes replaces an unpredictable 80-gram-carbohydrate fast-food meal with a 30-gram-carbohydrate shake, the net effect on blood sugar over weeks and months is positive, even though each individual shake still causes a temporary rise. The key distinction is between “does this raise blood sugar acutely?” (yes) and “does using this strategically improve blood sugar control?” (also yes, for many people).

Ensure After Exercise

Athletes and older adults sometimes use Ensure or similar shakes as a post-workout recovery drink. In this context, the blood sugar response is different from resting conditions, because exercise increases insulin sensitivity and muscles are actively pulling glucose from the bloodstream to replenish glycogen stores.

A study examining protein combined with different carbohydrate types after resistance exercise found that all carbohydrate-containing drinks raised blood glucose and insulin compared to a carbohydrate-free control. The high-glycemic carbohydrate drink produced the highest blood glucose at 30 minutes post-ingestion, but all three carbohydrate groups stimulated a large insulin response with no significant differences in insulin area-under-the-curve among the carbohydrate types.¹⁴ For someone without diabetes, post-exercise is actually one of the best times to consume a shake like Ensure, because the insulin surge helps shuttle amino acids into muscle tissue and the glucose gets absorbed quickly into depleted glycogen stores. For someone with diabetes, the same window of heightened insulin sensitivity means the blood sugar spike from a post-workout shake may be smaller than at other times, but it still warrants monitoring.

Practical Strategies If You Need to Use Ensure

Not everyone can choose to avoid Ensure. Older adults recovering from surgery, people with swallowing difficulties, cancer patients dealing with appetite loss, and anyone who simply cannot eat enough solid food may depend on nutritional supplements. If you are in that position and also managing blood sugar, a few strategies can minimize the glycemic impact:

Choose the right formula: A diabetes-specific product like Glucerna produces roughly half the blood sugar spike of standard Ensure, with similar calories and taste. This is the single most effective change you can make.
Sip slowly: Spreading the drink over 20 to 30 minutes flattens the glucose curve compared to drinking it quickly.
Pair with fiber or fat: A handful of almonds, a spoonful of peanut butter, or some raw vegetables eaten alongside the shake adds fiber and fat that slow carbohydrate absorption.
Time it after activity: If possible, drink your shake after a walk or some physical activity, when your muscles are more responsive to insulin.
Read total carbohydrates: Ignore the “sugars” line and focus on total carbohydrates per serving. Maltodextrin and other starches are just as glycemic as sugar itself.

If you use insulin, count the full carbohydrate content of the shake just as you would for food, and dose accordingly. The liquid format means absorption happens faster, so if you use a rapid-acting insulin, you may need to time the injection to coincide with or slightly precede the drink rather than taking it 15 minutes before as you might with a solid meal.

Who Should Actually Worry

For someone with normal glucose metabolism, a bottle of Ensure raises blood sugar temporarily and the body handles it without incident. The concern is real for people with type 2 diabetes, prediabetes, type 1 diabetes on insulin, gestational diabetes, or anyone on medications that interact with blood sugar. It is also relevant for hospitalized patients receiving tube feeding, where the rate and type of nutritional formula directly affect glycemic control and clinical outcomes.

Where confusion often arises is among people who have been told to drink Ensure for weight gain or nutritional support and then discover their blood sugar readings are higher than expected. This is not a side effect or an allergy. It is exactly what happens when you drink concentrated carbohydrates. The solution is not to stop supplementing nutrition but to switch to a formula designed for glucose management, slow down consumption, and coordinate with your healthcare provider on any medication adjustments. The blood sugar impact is predictable, manageable, and well-studied. It just requires treating these drinks with the same attention you would give any carbohydrate-rich food.