Good morning,
As we age and as you probably know, it becomes more difficult to retain our heat, particularly since the body temperature had already lowered from her being in a rested state.
You did well by checking her blood sugar trend as a drop from a higher level to a lower level can still cause problems such as shivering even if both values are somewhat "normal"
Also, if you ever do suspect
low blood sugar, please do not give honey which is a mixture of
glucose and fructose. Fructose will not raise the blood sugar quickly but glucose will. Glucose gel at the bedside for emergencies is good.
Now, to answer your question of should you be concerned. No not at this point as I explained above. Keep her hydrated, away from drafts, cover her adequately when she is resting and monitor her shivering episodes and what works and what doesn't.
If it continues, then I would check with a clinician and you will also have more information at that time. Please relax and do not be overly concerned.
Keep her at a good weight (no big weight losses), enough lean protein, cut up fresh fruits or fruits in own juice, follow good nutritious meal plan. If nutritional problems arise, best to consult a trained dietitian.
Otherwise, thanks for your empathy for your mom and the care you are giving. Sincerely, Kathy Shattler, MS,RDN