Short answer: most are safe for blood sugar. Long answer: some are better choices than others.
The clear winners
### Stevia Plant-derived. Zero calories. Zero glycemic impact. Slight bitter aftertaste at high doses. Decades of safety data.
### Monk fruit Fruit-derived. Zero calories. Zero glycemic impact. Less aftertaste than stevia. More expensive.
### Allulose A "rare sugar" that tastes nearly identical to sugar and behaves like sugar in baking. Zero glycemic impact. Generally well tolerated up to 0.5g per kg body weight.
### Erythritol Sugar alcohol. Almost zero glycemic impact. Can cause GI upset in large doses. Some 2023 research raised cardiovascular concerns — choose sparingly until more data exists.
The "controversial but probably fine"
### Sucralose (Splenda) Zero glycemic impact in most studies. Some animal data suggests gut microbiome effects. Likely fine in moderation.
### Aspartame (Equal, NutraSweet) Decades of research, FDA-approved. Avoid if you have phenylketonuria. WHO classified as "possibly carcinogenic" in 2023 — but the dose required is enormous.
### Saccharin (Sweet'N Low) Oldest artificial sweetener. Generally safe, slight aftertaste.
What to actually use
For coffee/tea: stevia or monk fruit. For baking: allulose. For drinks: brands sweetened with stevia/monk fruit.
Avoid: dextrose-blend "diet" products, sorbitol in large amounts, anything that lists multiple sweeteners (a marketing tell).