October 27, 2001
Daily Care, Type 2
Question from Riyadh, Saudi Arabia:
I am a 57 year old white male who has had type 2 diabetes for six years and on insulin for the past year. While I am approximately 15 pounds overweight and smoke heavily, my overall health is good. I exercise daily (20 minutes jogging), eat modestly (careful of fats and sugar), and rarely drink alcohol. I take my glucose reading just before each meal (usually no snacks between meals), and my daily medications consist of twice daily Mixtard insulin with Glucophage [metformin] three times per day.
Over the last 80 days, I have experienced high glucose readings (10-15 mmol/L [180-270 mg/dl] ) just before lunch for three periods ranging from three to nine days; 65% of these high lunchtime readings have been accompanied by high-end normal readings at breakfast. The periods high glucose readings are randomly separated by periods of normal readings. I can find no obvious correlation between the days of high lunch time readings and diet, exercise or daily activity. Two months ago, my A1c was 6.7%, and my lipid profile was normal.
Can you offer some explanation for the abnormally high lunch time readings? Can you advise on how to bring my lunch time glucose readings back to consistently normal values?
You sound like a motivated patient. I would suggest you shy away from a commercially mixed insulin [the Mixtard]and go to mixing your insulin. The convenience you lose will be made up by the flexibility you gain. For instance, your lunch and breakfast sugars are higher than desired. This would suggest a need to increase the evening NPH (to bring the fasting down) and the morning Regular insulin (to bring the pre-lunch down).
Your question about the hemoglobin A1c being relatively low in light of the elevated lunch sugars is a rather common question. Remember that the A1c provides you with an average blood sugar for the previous three months. It is an arithmetic mean and not a simple mean of the sugars. That means that your most recent sugars weigh more heavily than the distant blood sugars. Therefore, an explanation of your result may be that the elevation you have at lunch is relatively low, compared to good control throughout the rest of the day. In addition, you may have had these elevated values at lunch for a relatively short time, i.e., not long enough to raise the A1c result.
Finally, I would recommend you cut out the smoking. The interaction between diabetes and smoking is not good. Smoking exacerbates all the vascular problems associated with diabetes.