Hi, welcome to our site. I am Dr Saumya Mittal. Read your query. That is a very significant question and i appreciate your problem. I will try my best to answer your query I would suggest get your ecg done. The drug atenolol is a beta blocker. In other words, it slows the heart rate, thereby making the blood demand of heart less. But your weakness is possibly due to an excessively reduced heart rate. Beta blockers are known to cause higher than normal sugars. I have known patients whose sugars came back to normal as soon as the betablockers were stopped So I would suggest that 1. talk to your doctor and change the medicine- first due to possible low heart rate and second due to higher than normal sugars. 2. if your sugars were tested when consuming atenolol, check the sugar again once the medicine is changed. Also check HbA1c with the repeat sugars tested I hope this helps you. Inform the reports mentioned above so i can be of help further. Best of luck. I have given you the answer to the maximum considering the information provided. The results of the tests could further enhance my answer to you. Please do understand that some details could be extracted from a detailed history and examination. Looking forward to your return query with the details asked so that I can help you further. (If the answer has helped you, please indicate this)