Table 3.
Overview of Main Study Findings with Respect to Weight and Adherence
| Author/Year | Study Drug(s) | Weight Measure | Adherence | Absolute Weight Change/ Proportion of PwD with Weight Change from Baseline (95% CI where Reported) | Weight Loss Associated with Better Adherence | Weight Gain Associated with Better Adherence | |
|---|---|---|---|---|---|---|---|
| Adherent | Non-adherent | ||||||
| Studies reporting absolute weight loss (kg) and adherence | |||||||
| Patel et al, 201942 | Liraglutide plus BI | Baseline to 6 months | Amount of medication used/amount expected to be used over days between clinic visits (adherent: measure assessed at 2/3 clinic visits and time-adjusted adherence rate for study duration ≥80%) | –1.3 kg (–0.32, 0.7) | +0.3 kg (–2.2, 2.9) | ✔ | |
| BBI | +4.6 kg (2.2, 7.0) | +2.1 kg (0.1, 4.0) | ✔ | ||||
| Study author observation: “Those with ≥80% adherence, compared with those who had lower adherence, had numerically greater effects on … weight” | |||||||
| Carls et al, 201737 | GLP-1 RA | Baseline to 1 year | PDC (adherent: ≥0.80) | –3.77 kg | –2.04 kg | ✔ (p<0.01)a | |
| DPP-4i | –1.18 kg | –1.29 kg | No effect | ||||
| SU | +0.85 kg | –0.26 kg | ✔ (p<0.01)a | ||||
| Study author observations: “Adherence to GLP-1 RA appears to enhance its weight-loss effect and adherence to SU appears to amplify weight gain. In contrast, patients treated with DPP4 experience small weight changes and adherence to DPP4 treatment had no effect on weight” | |||||||
| Gordon et al, 201838 | OAD monotherapy | Baseline to 1 year | MPR (adherent: ≥0.80) | –2.65 kg (–2.80, –2.50) | –1.64 kg (–1.94, –1.34) | ✔ (p<0.001)a | |
| OAD dual therapy | +0.67 kg (0.46, 0.88) | +0.31 kg (–0.22, 0.83) | ✔ | ||||
| OAD triple therapy | +0.50 kg (0.03, 0.97) | +0.26 (–0.65, 1.17) | ✔ | ||||
| Study author observations: “Within each OAD cohort, adherent patients tended to lose more weight (OAD monotherapy) or gain more weight (OAD dual and triple therapy) compared with non-adherent patients” | |||||||
| McAdam-Marx et al, 201441 | Pooled metformin, GLP-1 RA, SU, TZD, DPP-4i, and insulin | Baseline to 6 months | MPR (adherent: ≥0.80) | –1.6 kg | –1.3 kg | ✔ | |
| MARS-5 (adherent: 25) | –1.7 kg | –1.1 kg | ✔ (p=0.016)b | ||||
| Study author observations: “Adherent patients had significant changes in body weight from baseline, but non-adherent patients did not” “Self-reported adherence to diabetes medication was associated with weight loss ≥3%” | |||||||
| Studies reporting categorical weight loss and adherence | |||||||
| Durden et al, 201945 | GLP-1 RA | >3% body weight loss at 3–6 months | PDC (adherent: ≥0.80) | Early weight-loss responders: 43.3% No early weight-loss effect: 38.0% (p<0.001) |
✔ (OR [95% CI], 1.18 [1.02, 1.36])c |
||
| Study author observations: “Early response was associated with a higher likelihood of medication adherence … over a period of up to 18 months compared with those patients who did not achieve changes of … >3% reduction in body weight within 3–6 months” | |||||||
| McAdam-Marx et al, 201440 | All | ≥3% body weight loss at 6 months | MARS-5 (adherent: 25) | 29.9% | 24.2% | ✔ | |
| Metformin | 47.1% | 42.1% | ✔ | ||||
| GLP-1 RA | 50.0% | 40.0% | ✔ | ||||
| SU | 16.5% | 11.5% | ✔ | ||||
| TZD | 23.8% | 16.7% | ✔ | ||||
| DPP-4i | 20.8% | 16.7% | ✔ | ||||
| Insulin | 27.5% | 12.9% | ✔ | ||||
| Other | 25.0% | 0% | ✔ | ||||
| Study author observations: “This study showed that medication adherence is associated with … weight loss” | |||||||
Notes: ✔: Numerical (not statistically significant) difference or difference based on author conclusions; ✔ (p-value)a: statistically significant difference between adherent and non-adherent PwD reported; ✔ (p-value)b: from SEM, adherent PwD were more likely to experience weight loss compared with non-adherent PwD when assessed by MARS-5 (OR 1.70, 95% CI 1.11, 2.61); however, no significant association found with adherence assessed by MPR (OR 1.59, 95% CI 0.66, 3.83; p = 0.305); ✔c: odds of early weight-loss responders being adherent versus those with no early weight-loss response.
Abbreviations: BBI, basal-bolus insulin; BI, basal insulin; CI, confidence interval; DPP-4[i], dipeptidyl peptidase 4 [inhibitor]; GLP-1 RA, glucagon-like peptide-1 receptor agonist; MARS-5, 5-item Medication Adherence Report Scale; MPR, medication possession ratio; NS, not statistically significant; OAD, oral antidiabetes drug; PDC, proportion of days covered; PwD, people/person with diabetes; SU, sulfonylurea; TZD, thiazolidinedione.