Does carvedilol really control blood pressure better than metoprolol?

I read the GEMINI trial, a classic landmark study that compared the effect of randomized carvedilol v metoprolol on glycemic control and blood pressure. The article I'm attaching here is a subsequent, more detailed exploration into their blood pressure findings.

Of note, this study did exclude patients with "significant cardiovascular disease" including bradycardia, UA, CHF, and MI/CVA in the 3 months prior, which limits external validity a bit. And while all the patients had diabetes, less than 10% carried a diagnosis of CAD. Finally, 12.5% of participants were African-American. With those caveats for our Grady Clinic patients . . .

With respect to blood pressure, the authors did not find any significant difference between metoprolol and carvedilol, re: both final BP measurement and need for additional anti-hypertensive drugs. Interestingly, not all patients were maxed out on their BB dose, for reasons not clear to me. Here is a nice picture comparing the two drugs directly:

Figure 3. Blood pressure and heart rate at baseline and study end. CI, confidence interval; SBP, systolic blood pressure; DBP indicates diastolic blood pressure; HR, heart rate.

That said, when the authors looked at specific drug combinations and their effects on systolic and diastolic blood pressure, it appears that the regimen of an ACEI/ARB + carvedilol + CCB +/- thiazide was ideal:

Figure 4. Additional diastolic blood pressure (DBP) reduction with use of adjunct medication in addition to carvedilol (Carv) or metoprolol (Met) and specific renin‐angiotensin system inhibitors

The group treated with metoprolol did have more weight gain and higher A1cs at the end of the study period, and more patients in this group dropped out due to adverse events. On the other hand, carvedilol appeared more helpful in terms of insulin resistance.

I put all this together and feel comfortable continuing to utilize carvedilol over metoprolol for blood pressure control, at least in my patients with diabetes mellitus. Even if I can't find randomized data to support the efficacy, I think the tradeoff and reassurance about glycemic control are worth it.

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Bakris GL, Fonseca V, Katholi RE, et al. Metabolic Effects of Carvedilol vs Metoprolol in Patients With Type 2 Diabetes Mellitus and Hypertension. JAMA. 2004;292(18):2227. doi:https://doi.org/10.1001/jama.292.18.2227

Wright JT, Bakris GL, Bell DSH, et al. Lowering Blood Pressure With β‐Blockers in Combination With Other Renin‐Angiotensin System Blockers in Patients With Hypertension and Type 2 Diabetes: Results From the GEMINI Trial. The Journal of Clinical Hypertension. 2007;9(11):842-849. doi:https://doi.org/10.1111/j.1524-6175.2007.07251.x