Using CGM to Manage T2D
10 mins read

Using CGM to Manage T2D

Data derived from continuous glucose monitoring (CGM) devices can help guide nutrition management and insulin dosing in people with type 2 diabetes (T2D) in primary care settings.

At the Advanced Technologies & Treatments for Diabetes meeting, two experts from the International Diabetes Center – HealthPartners Institute, Minneapolis, offered advice for clinicians. Tara Ettestad, RN, LD, CDCES, program manager for care transformation and training at the center, shared tips for helping patients change their diet based on CGM readings. The center’s medical director Thomas Martens, MD, provided a systematic approach to using CGM to guide adjustment of insulin doses and other medications for insulin-treated patients with T2D.

CGM-Guided Nutrition: Focus on Sustainable Changes

With CGM, people with diabetes get real-time feedback about the impact of foods on their glucose levels. This can help them learn not just what they can’t eat but what they can eat, Ettestad pointed out.

“People want to know what to eat. This is the number-one question that people who are newly diagnosed with diabetes ask, and unfortunately, they typically hear what not to eat. No carbohydrates, no sugar, no white foods, no sweets. This can be really disheartening and confusing for many. We should be focusing on sustainable changes to help improve diets,” she said.

She added, “Not everyone can see a dietician, but all clinicians can help provide evidence-based nutrition guidance.”

When guiding patients, it’s important to focus on the four “core concepts” outlined in the American Diabetes Association’s nutrition consensus report:

  1. Emphasize nonstarchy vegetables
  2. Minimize added sugars and refined grains
  3. Eat more whole foods, less highly processed foods
  4. Replace sugar-sweetened beverages with water as often as possible

With CGM, patients can see the differences in response to refined carbs (wheat, rice, and potato), sugars (sucrose, fructose, and glucose), and resistant starches (whole grains, fruits, and vegetables). Typically, glucose responses are steeper and higher for the first two compared to resistant starches.

CGM can also show the effects of eating fat and protein, in that they can delay glucose responses to meals even with the same carbohydrate content, Ettestad said.

It’s important to remind patients that although one goal of using CGM is to reduce post-meal glucose spikes, eating a lot of high-saturated fat, high-calorie foods isn’t the healthful way to do it. “What’s really important when we’re using CGM to help guide nutrition is remembering nutrition quality and what can be good for glucose is not always good for our overall health,” Ettestad stressed.

She provided these further tips:

  • Pick one meal at a time to focus on. Collaborate with patients to see what changes they are able and willing to make. For example, rather than entirely giving up rice or noodles at dinner, try eating less of those and adding more vegetables.
  • Suggest that patients keep a food log or use a tracking app so that the source of specific glucose patterns can be identified and addressed.
  • Show patients how to check their time in range (TIR) ​​on their mobile device or reader each week so they can see big-picture results of their changes. “This can be really motivating for people to see,” she said.
  • Remind people that glucose rises with meals. This seems obvious but may not be to those newly diagnosed, she pointed out.
  • Educate patients on glucose targets and explain that other factors such as stress and activity can influence glucose levels.
  • Focus on the positive. “What have you been learning about how your meals and beverages affect your glucose?”
  • Help guide patients toward better diet quality, even when TIR is a goal, using the four core concepts.
  • Encourage curiosity, such as by experimenting with portions, timing, or food order. “What if you try eating nonstarchy foods first?”
  • Before adjusting a medication dose, consider asking if the patient is willing to make a nutrition change. “Every visit is an opportunity!”

Adjusting Insulin With the Help of CGM: Focus on Four Patient Subgroups

Martens noted that about a quarter of people with T2D will require insulin treatment, despite increasing use of sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. And even when insulin is used as a “salvage therapy” in T2D, about two thirds of those individuals still struggle to achieve an A1c below 7% with or without other glucose-lowering medications, he noted.

“So, we have this huge population with type 2 diabetes who have limited access to endocrinology, and advanced insulin delivery devices are not yet available for them. Can better use of CGM drive improvements in care?”

He pointed to MOBILE, a randomized clinical trial, which showed that CGM use resulted in significantly improved A1c at 8 months compared with fingerstick monitoring among adults with T2D taking long-acting insulin alone without premeal insulin. However, TIR was still just 59% (vs 43% with fingerstick testing), suggesting room for improvement.

“This could have been much, much better…Rapid interpretation isn’t really enough. We need to move from interpretation into action,” Martens said.

His team recently developed a program called “CGM Clinician Guided Management (CCGM)” aimed at primary care that encourages the following principles:

  • Appropriate movement toward the safer “high value” noninsulin therapies, that is, GLP-1 agonists and SGLT2 inhibitors.
  • Appropriate insulin titration.
  • Appropriate cycle time in titration, that is, accelerating more rapidly when one dose isn’t working. “That’s the Achilles heel of primary care,” he noted.
  • Quick identification of when the limits of basal insulin therapy have been reached.
  • Team-based management for difficult situations and for individuals on multiple daily injections and mealtime insulin regimens. “This is a group that really struggles…in primary care settings,” he noted.

The following three steps are based on published T2D management guidelines:

  • Step 1: If the patient has atherosclerotic cardiovascular disease, start with either an SGLT2 inhibitor or GLP-1 agonist. For those with congestive heart failure and/or chronic kidney disease, SGLT2 inhibitors are indicated.
  • Step 2: Is the patient on sulfonylurea? Consider eliminating it before moving to CGM-based insulin titration.
  • Step 3: Was there a change in therapy based on steps 1 or 2? If not, move to CGM-guided insulin titration. If yes, wait 2-4 weeks to see the impact of therapy change before moving on.

The program categorizes patients into one of four groups based on CGM data, with respective management approaches:

  • Category 1: TIR > 70%, time below range (TBR) < 3%: Doing well, keep on going!
  • Category 2: TIR > 70%, TBR ≥ 3%: Too much hypoglycemia, need to decrease therapy. Stop sulfonylureas, and if TBR > 10%, also decrease basal insulin dose.
  • Category 3: TIR < 70%, TBR < 3%: Too much hyperglycemia — increase therapy.
  • Category 4: TIR < 70%, TBR ≥ 3%: This is the toughest category. Fix or advance therapy. These patients should be either referred to a diabetes care and education specialist (formerly known as "diabetes educators") to troubleshoot their regimens or have their therapy advanced to multiple daily injections. The hypoglycemia should be addressed first for safety, then the hyperglycemia.

“We hope that CCGM is going to be the translation of CGM data into action in primary care, where we struggle with action and inaction,” Martens said. It’s expected to be posted on the IDC website soon.

Ettestad’s employer received educational grant funds from Abbott Diabetes Care and Sanofi-Aventis Groupe. She also worked as a product trainer with Tandem Diabetes Care. She is employed by nonprofit International Diabetes Center – HealthPartners Institute and received no personal income or honoraria from these activities. Martens’ employer received funds on his behalf for research and speaking support from Dexcom, Abbott Diabetes Care, Medtronic, Insulet, Tandem, Sanofi, Lilly, and Novo Nordisk and for consulting from Sanofi and Lilly. He is employed by nonprofit Health Partners Institute dba International Diabetes Center and received no personal income or honoraria from these activities.

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape Medical News, with other work appearing in the Washington Post, NPR’s Shots blog, and Diatribe. She is on X: @MiriamETucker.

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