Primary Care Corner with Geoffrey Modest MD: Does glucose home-monitoring help???

by Dr Geoffrey Modest

A recent article added to some prior literature suggesting that glucose self-monitoring is not so effective in type II diabetics not on insulin (see doi:10.1001/jamainternmed.2017.1233 ).



— 450 patients were enrolled in this pragmatic, open label randomized trial, of which 418 completed the final visit. All were in established primary-care relationships in North Carolina, had a hemoglobin A1c between 6.5% and 9.5%, and were randomized into one of 3 wings: no self-monitoring of blood glucose (SMBG), once daily SMBG, or once daily SMBG with enhanced patient feedback including automatic tailored messages delivered via the meter that were intended to educate and motivate patients with an algorithm that took into account the blood glucose value, time of day, and relationship to food intake.

— Median age 61, 46% male, 33% black/62% white, 60% high school or some college/34% college or higher, BMI 33, 38% with low health literacy, mean duration of diabetes 6 years, 3 comorbidities, current use of SMBG 75%, diabetic meds were metformin 80%/sulfonylurea 36%/TZD 5%/DPP-4 inhibitor 9%

— baseline hemoglobin A1c 7.6%

— Primary outcomes were: hemoglobin A1c level and health-related quality of life at 52 weeks



— testing adherence declined in both of the SMBG groups (though more so in the group with messaging!): daily testing overall going from around 95% initially to 60% at 12 months; for the no SMBG group, 24% tested at least a few times/month and only 9% tested less than once/month

— follow-up hemoglobin A1c’s were:

— no SMBG: baseline 7.52, follow-up 7.55

— SMBG, no messaging: 7.55, follow-up 7.49

— SMBG, with messaging: 7.61, follow-up 7.51

— there was no significant difference between hemoglobin A1c levels across all 3 groups (p=0.74), with estimated adjusted mean A1c difference:

— SMBG with messaging vs no SMBG: -0.09% (-0.31% to 0.14%)

— SMBG vs no SMBG: -0.05% (-0.27% to 0.17%) [as a reference here, a 0.5% difference (10x this difference) is considered to be clinically significant]

— there was no significant difference in health-related quality of life.

— there was no significant difference in adverse events including frequency of hypoglycemia, healthcare utilization, or insulin initiation

— there was no significant difference in almost all of the secondary outcomes, including the diabetes empowerment scale, diabetes treatment satisfaction scale, and the communication assessment tool.



— prior studies have been mixed on the role of SMBG in non-insulin using patients, though more than 75% do regular SMBG

–there were several limitations of the study, many noted by the authors: this study really reflected whether it was useful to continue SMBG, since most patients had already been doing so (ie, not whether initiating SMBG mattered for those not doing so); and there was a selection bias in that all participants were willing to be randomized into a group not using SMBG. Also, about 40% in the daily testing group stopped doing so (though not sure what that means, since they don’t say whether this is decreasing testing to 6x/week or 1x/month…)


the bottom line here: I think that it can be useful to have some home-based glucose monitoring for a few reasons, including fuller details on blood sugar swings during the day, with the potential:

–to elucidate to the patient what tends to make the blood sugar go up or down (eg, it was the last meal with rice which raised the blood sugar, or doing exercise lowered it….). This real-time feedback can well inform the patient on what lifestyle issues either improve or worsen blood sugars, leading to appropriate tweaking of them. in my experience, after suggesting to patients that they monitor their blood sugar 1-2 hours after a meal, that the patients are better able to identify triggers to higher blood sugars. and, sometimes, they are able to modify their diets

–to adjust medications to cover these higher or lower levels, if lifestyle changes would not help

–but I think that the main message from this study, as well as prior ones, is that our primary focus as clinicians should not be primarily to strongly encourage/berate patients about checking their blood sugars at home, but to focus on lifestyle changes and medication adherence. as I have mentioned in prior blogs, I think that diabetes treatment is one of the hardest issues I deal with in clinical medicine. it brings to the fore the multitude of issues and obstacles to treating this complicated disease, including the difficulty in eating well/exercising (access to good foods, ability/time to cook healthy meals, access to good exercise venues including safe streets to walk on/time to do so in our overprogrammed lives, and generally competing with a culture and with persuasive advertising to eat poorly, sit at home watching TV, work 2 jobs to survive, etc, which are perhaps the most important underpinnings for our diabetes epidemic.)  these are the hard issues for our patients, and i think the primary ones to focus on. And really focusing on  the importance of SMBG​ can actually dilute/divert this pivotal message of the importance of lifestyle changes.

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