Impact of baseline insulin regimen on glycemic response to a group medical clinic intervention

Group medical clinics (GMC) combine medication management and self-management training, and may improve diabetes outcomes. It remains unclear which patients benefit most from GMC. This secondary analysis examined the impact of baseline insulin regimen on GMC response.

We analyzed a trial of 239 veterans with type 2 diabetes randomized to GMC or usual care (UC). We categorized baseline insulin regimen as the following: no insulin; basal insulin only; or complex insulin (basal-prandial or mixed regimens). Using linear mixed models adjusted for clustering within GMC, we evaluated the differential impact of GMC relative to UC on hemoglobin A1c (HbA1c) and self-efficacy among patients on different baseline insulin regimens.

From linear mixed models, the effect of GMC on HbA1c differed by baseline insulin regimen versus UC (P = 0.05); there was no differential effect on self-efficacy (P = 0.29). Among those using complex insulin regimens at baseline, GMC reduced HbA1c by study end compared with UC (-1.0%; 95% CI -1.8 to -0.2; P = 0.01). We found no such HbA1c difference between GMC and UC patients using no insulin (P = 0.65) or basal insulin only (P = 0.71). There were no clinically significant differences in hypoglycemia by baseline insulin regimen and intervention group.

We found that compared with UC, GMC lowered HbA1c specifically among patients using complex insulin regimens at study baseline, which may relate to this group's demanding medication and self-management requirements. Implementing GMC among patients using complex insulin regimens may maximize this care delivery strategy's potential.